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 PREFACE
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COMBAT ENGINEER
PART I
CORRESPONDENCE COURSE
U.S. ARMY ENGINEER SCHOOL
This reprint includes Lesson Change #1 dtd 19 Jan 75
MOS: 12B20
INTRODUCTION
_____________________________________________________________________________
This is one of a series of subcourses in­
tended to assist enlisted personnel of the
Army to improve their proficiency in engineer
MOS job requirements. This study should
increase your job knowledge and your chances
of qualifying for proficiency pay and/or pro­
motion.
This subcourse and one entitled Combat
Engineer­­Part II are oriented toward as­
sisting the student already qualified as a
Pioneer, MOS 12A10, to qualify as a Combat
Engineer, MOS 12B20. The lessons compris­
ing Part I are concerned mainly with activi­
ties which facilitate operations of friendly
combat forces; those in Part II cover activi­
ties which, for the most part, impede the
enemy.
This subcourse consists of nine lessons and
an examination as follows:
LESSON NO. LESSON TITLE REFERENCES
1 2 Reconnaissance and Intelligence S/C 54, FM 5­30, FM 5­36
3 Handtools and Rigging S/C 34, TM 5­461, TM 5­725
4 Engineer Equipment S/C 66, TM 5­331A, C, D
5 Construction Planning S/C 67, TM 5­333
6 Soils in Construction S/C 53, TM S­330
7 Roads and Culverts S/C 64, TM 5­330, FM 5­34
8 Bridges S/C 59, TM 5­277, TM 5­312
9 Expedient Stream Crossings FM 6­34, TM 5­210
Examination.
Twenty­six hours are accredited for this
subcourse.
The information in the attached memo­
randums accompanying the lessons should be
sufficient for you to answer the questions at
the ends of the lessons and those in the ex­
amination. If you need additional informa­
tion, you should use the references listed
above.
You will not be limited as to the number
of hours you may spend on any lesson or the
examination.
* * * IMPORTANT NOTICE * * * THE PASSING SCORE FOR ALL ACCP MATERIAL IS NOW 70%.
PLEASE DISREGARD ALL REFERENCES TO THE 75% REQUIREMENT.
LESSON 1
MAP READING
CREDIT HOURS _____________
TEXT ASSIGNMENT __________
MATERIALS REQUIRED _______
LESSON OBJECTIVE _________
_____________________________________________________________________________
LESSON
CHANGE
NO. 1
Engineer Subcourse 0501­1, Combat Engineer I, Edition 1, is changed
as follows: Introduction: Delete all references to Lesson 1, Map Reading
Lesson 1: Delete in its entirety. This lesson contains
outdated material that is no longer available
for distribution. Information on map reading
may be obtained by enrolling in EN 5320­2, Map
and Aerial Photograph Reading I.
1­1
LESSON 2
INTELLIGENCE AND RECONNAISSANCE
CREDIT HOURS _______________________2
TEXT ASSIGNMENT ____________________Attached memorandum.
MATERIALS REQUIRED _________________None.
LESSON OBJECTIVE____________________To increase your knowledge of engineer in­
telligence and reconnaissance.
______________________________________________________________________________
ATTACHED MEMORANDUM
1. DEFINITIONS
Tactical intelligence is evaluated informa­
tion and conclusions about the enemy includ­
ing capabilities and vulnerabilities, the
weather, and geographic features of the ter­
rain.
Terrain intelligence is concerned with na­
tural and manmade terrain features, weather
and climate of a particular area or region.
Technical intelligence pertains to design,
operation, nomenclature, physical character­
istics, performance, operational capabilities,
and limitations of foreign material and facili­
ties used by or for the support of military
forces.
2. THE INTELLIGENCE CYCLE
Step 1. Planning the collection effort and
preparing orders.
Step 2. Collecting the information.
Step 3. Processing the collected informa­
tion.
Step 4. Disseminating and using the re­
sulting intelligence.
Note: Steps 1, 3, and 4 are accomplished
by the commander and the intel­
ligence officer.
3. SOURCES OF INFORMATION
Ground reconnaissance.
Aerial reconnaissance.
Maps.
Captured enemy documents.
Aerial and ground photography or other
imagery.
Other documents, including texts, periodi­
cals, and technical papers.
Captured enemy material.
Captured enemy installations.
Prisoners of war.
Local civilians.
Refugees and military returnees.
Published intelligence and terrain studies.
Note: In fast moving situations, ground
and short­range aerial reconnais­
sance, reports from front line
troops and prisoners of war may be
the only sources used by a division
since the information is more im­
mediate, detailed and local.
4. SALUTE
Reported enemy information should include
the following:
Size of unit or installation observed.
Activity that occurred during observa­
tion.
2­1
Location of activity (direction of move­
ment, also).
Unit designation.
Time of observation.
Equipment used or on hand, including
weapons and vehicles.
5. TACTICAL RECONNAISSANCE
For offensive operations, collection of in­
formation is continuous and detailed prior
to the advance, during the advance, and
during the attack. Emphasis: conditions of
route of advance, alternate routes, air­landing
facilities, enemy obstacles, local engineer ma­
terials, river crossing sites and hydrology, and
possible water points.
For defensive operations, collection is con­
tinuous and detailed and is intensified im­
mediately upon the decision to occupy a posi­
tion. Emphasis: terrain studies, lines of
communication for counterattack forces, loca­
tion of obstacles, and demolition sites, and
natural cover.
For retrograde operations, collection em­
phasizes roads, bridges, terrain, installation,
and natural resources in the territory through
which the move will occur.
For fortified areas, emphasis is placed on
obstacles in front and on the flanks of the
enemy position, minefields, location of de­
fending weapons, and contaminated areas.
6. ENGINEER RECONNAISSANCE REPORT
(Fig. 1 through 5)
Heading: Designation of officer who or­
dered the reconnaissance and commander of
unit performing the reconnaissance; name,
rank, and organization of reconnaissance
party leader; time and place reconnaissance
was made; maps used; delivery address for
report.
Body: contains the following:
Key: serial or critical point number (also
used on overlay).
Object: conventional symbol or brief
written description of object.
Time: time object observed.
Work estimate?: "yes" if included on
back of report; otherwise, "no."
Additional remarks and sketch: grid co­
ordinates of object; explanation; calculations;
sketch as necessary.
Signature block: commander of unit per­
forming the mission.
Work estimate: reverse side of form used
to indicate amount and type of effort re­
quired for construction or repair.
7. ROAD RECONNAISSANCE REPORT
(Fig. 6 and 7)
Heading: As shown in blocks.
Section I: As shown in blocks; item 6 in­
dicates the lower and upper limits of the
traveled way width.
Section II: As shown in blocks; when this
data varies for different sections of the road,
differences are indicated on the mileage chart
by placing the "road classification formula"
(to be covered later) by the appropriate
portion of the road.
Section III: Obstructions; serial numbers
are also used on overlay and on mileage chart.
Mileage chart is on the reverse side of the
form.
8. ROAD CLASSIFICATION FORMULA
Prefix: The formula is prefixed by the
letter "A" if there are NO LIMITING CHAR­
ACTERISTICS. The letter "B" is the prefix
if there are ANY LIMITING CHARACTER­
ISTICS.
Limiting Characteristics Symbol
Curves (radius 30 m or less) c
Gradients (7% or more) g
Drainage (inadequate) d
Foundation (unstable) f
Surface condition (rough) s
Camber or superelevation (excessive) j
2­2
2­3
2­4
2­5
2­6
An unknown or undetermined characteristic
is represented by a question mark following
the symbol of the feature to which it refers,
both enclosed in parentheses, e.g., (d?).
Width: Width of the traveled way ex­
pressed in meters or feet followed by a slash
and the combined width of the traveled way
and the shoulders, e.g. 14/16 m.
Road Surface Material: Road surface ma­
terial is expressed by a letter symbol as fol­
lows:
Symbol Material
k Concrete
kb Bituminous or asphaltic concrete
(bituminous plant mix)
p Paving brick or stone
rb Bitumen­penetrated macadam wa­
terbound macadam with super­
ficial asphalt or tar cover
r Waterbound macadam, crushed
rock, or coral
l Gravel or lightly metaled surface
nb Bituminous surface treatment on
natural earth, stabilized soil,
sand­clay or other select material
b Used when type of bituminous con­
struction cannot be determined
n Natural earth, stabilized soil, sand­
clay, shell cinders, disintegrated
granite, or other select material
v Various other types not mentioned
above (indicate length when this
symbol is used)
2­7
2­8
2­9
Length: Length of road in km or miles
may or may not be shown. If shown, place in
parentheses, e.g., (7.2 km).
Obstructions: Expressed as (Ob) when
existing on road, e.g., overhead clearances
less than 4.25 m, reduction in the traveled
way widths below the standards of table 3
below, gradients of 7% or greater, curves
with radii less than or equal to 30 m (100 ft),
and fords.
Special Conditions: Snow blockage (T)
and flooding (W) are used when the condition
is regular, recurrent, and serious.
Example 1: A 5.4/6.2m k; road has no
limiting characteristics with 5.4 m traveled
way, combined width of 6.2 m traveled way
and shoulder, and a concrete surface.
Example 2: Bcgs 14/16 ft 1 (2.4 km) (Ob):
Road has limiting characteristics of sharp
curves, steep grades, and a rough surface
condition; 14 ft of clear traveled way, 16 ft
combined with shoulders; a graveled or light­
ly metaled surface; 2.4 km length; obstruc­
tions are present.
Example 3: Bcgd (f?)s 3.2/4.8 m nb (4.3
km) (Ob) (T): Road has limiting character­
istics of sharp curves, steep grades, bad
drainage, unknown foundation condition, and
rough surface; 3.2 m wide traveled way, 4.8
m wide with shoulder; a bituminous surface
treatment; 4.3 km long, and it contains ob­
structions. The road is subject to snow block­
age.
Note: The formula is used on the mileage
chart of the Road Reconnaissance
Report.
9. CRITICAL DIMENSIONS
Clearance, width, and trafficability criteria
are shown in tables 1 through 4.
Measuring width of roadway and horizontal
and vertical clearances for tunnels, under­
passes, and through truss bridges:
10. DETERMINING RADIUS OF CURVES AND
GRADIENTS
RADIUS:
R = Cý/8m + m/2
R = radius of curve (circle)
C = length of cord
m = perpendicular distance from cen­
ter of cord to centerline (CL) of
road
Example 4: If the length of the cord is 58
feet and the perpendicular distance from the
cord to the centerline of the road is 5 feet,
what is the radius of the curve?
2­10
2­11
Vertical distance
percent of slope = ­­­­­­­­­­­­­­­­­­­­ x 100
Horizontal distance
Example 5: If the horizontal distance be­
tween points A and B is 200 meters and point
A is 18 meters higher than point B, what is
the gradient from point A to point B?
Vertical distance Gradient = ­­­­­­­­­­­­­­­­­­­ x 100
Horizontal distance
­18 = ­­­ x 100
200
= ­.09 x 100
= ­9% (minus means it is down­
hill from A to B)
An instrument for directly measuring per­
cent of slope is known as a clinometer.
An expedient method of estimating per­
cent of slope is based on the line of sight of
a man and the measurement of ground dis­
tance by use of the pace. The eye level of
the average man is 1.75 meters (5 ft, 7 in)
above the ground. The pace of the average
man is .75 meter (30 in).
Note: These measurements should be ac­
curately determined for each mem­
ber of a reconnaissance team.
To determine percent of slope, the indivi­
dual, who stands at the bottom of the slope
and keeps his head and eyes level, sights on
a spot up the slope. This spot should be easily
identifiable or, if not, another member of the
team may be sent forward to mark the loca­
tion. The individual making the sighting then
walks forward to the marked spot recording
the number of paces. This procedure is re­
peated until the top of the slope is reached­­
fractions of an eye level height must be esti­
mated. Vertical distance is then computed
by multiplying the number of sightings by
the eye level height. Horizontal distance is
computed by totaling the number of paces
and converting to meters by multiplying by
the factor, .75. Percent of slope can then be
calculated by substituting the values into the
percent of slope formula (see example 5a).
2­12
Because this method considers horizontal
ground distance and incline distance as equal,
reasonable accuracy may be obtained for
slopes only less than 30 degrees. Moreover,
this method requires considerable practice to
achieve acceptable accuracy.
11. BRIDGE RECONNAISSANCE REPORT
(Fig. 8 and 9)
Heading: As shown in blocks.
Essential Information: Serial number, lo­
cation, horizontal clearance, underbridge
clearance, number and description of each
span (new line on report for each different
span). In column 8 place an "X" beside the
span length if the span is not useable because
of damage and a "W" beside the span length
if the span is over water. Symbols for use
in column 7 (type of construction material)
are as follows:
Steel or other metal a
Concrete k
Reinforced concrete ak
Prestressed concrete kk
Stone or brick p
Wood n
See paragraph 12 for column 6 (type of con­
struction).
Additional Information: Military load class,
overall length, roadway width, vertical clear­
ance, bridge bypass, description of approaches
to bridge, characteristics of features spanned
by bridge, abutments, intermediate supports,
and bridge structural data. Other remarks
as appropriate.
Sketches: As indicated, reverse side.
Computation of Bridge Class: Utilize
Bridge Design and Classification Card (GTA
5­7­5).
2­13
2­14
2­15
2­16
2­17
2­18
2­19
2­20
12. TYPES OF BRIDGE CONSTRUCTION
The numbers shown below are used in
column 6 (Bridge Reconnaissance Report) to
indicate type of construction:
Use (9) and a written description for all
other type span construction, such as swing,
lift, cantilever, bascule.
13. TUNNEL RECONNAISSANCE REPORT
(Fig. 10 and 11)
All blocks are self­explanatory. See para­
graph 9 for blocks 14 and 15, and paragraph
10 for block 16. Sketches are self­explana­
tory.
14. FORD RECONNAISSANCE REPORT
(Fig. 12 and 13)
All blocks are self­explanatory. Show di­
rection of flow in sketch. Include a photo­
graph when possible which includes ap­
proaches and shows military vehicle fording
the stream.
A ford is a location in a water barrier where
the physical characteristics of the current,
bottom, and approaches permit the passage
2­21
2­22
of personnel and/or vehicles and other equip­
ment which will remain in contact with the
bottom.
15. FERRY RECONNAISSANCE REPORT
(Fig. 14 and 15)
All blocks are self­explanatory. Item 12
should indicate seasons or dates when ferry
is inoperable.
16. OVERLAY (Fig. 16)
It contains critical dimensions and meas­
urements needed by the commander to evalu­
ate the road net. The route classification and
significant features are indicated by standard
military symbols. A title block, grid refer­
ence marks and magnetic north arrow are
included.
17. MILITARY SYMBOLS
Note: The left and right bank of a stream
are determined by looking in the
direction of the current down­
stream. Special attention must be
paid when recording approach con­
ditions on the symbol; in the fol­
lowing symbol the wavy line
indicates the approach on the left
shore is easy, while on the right
shore it is difficult:
Any overhead clearance of a bridge less
than the standards of table 1 is underlined.
Any width of a one­lane or two­lane bridge
which is less than the standards of table 2
is underlined. The two­way class of any
two­lane bridge is downgraded if the width
of the bridge is less than the standards of
table 2.
The width of the traveled way of tunnels
or underpasses which is less than that of the
outside route is underlined.
Engineer resources symbols as shown be
low are also included on the overlay:
2­23
18. ROUTE CLASSIFICATION
Width of the route refers to the width of
the narrowest road on the route (in meters
or feet).
Type is the least desirable type road on the
route (X, Y, or Z).
X ­ hard­surface all­weather.
Y ­ light­ or loose­surface, limited all­
weather (crushed rock, waterbound
macadam, gravel, lightly metalled
surface).
Z ­ light­ or loose­surface, fair­weather
(natural or stabilized soil, sand­
clay, shell, cinder, disintegrated
granite).
Military Load Classification is the maxi­
mum class of vehicle which can use the route
(normally the one way classification of the
weakest bridge).
Obstructions are factors which limit the
traffic capacity (Ob, par 8).
Route Classification Formula utilizes the
four factors in sequence.
Example 6: 20 ft Y 50 = 20 ft minimum
width, limited all­weather type, maximum
load class 50, no obstructions.
Example 7: 10.5 m X 70 = 10.5 meters
minimum width, all­weather type, class 70.
Example 8: 20 ft Y 50 (Ob) = 20 ft mini­
mum width, limited all­weather type, class 50
with an obstruction (one or more). In addi­
tion to (Ob), (T) for snow blockage or (W)
for flooding may be used.
Note: See figure 16 for use of classifica­
tion on overlay.
EXERCISES
First requirement. Multiple­choice exer­
cises 1 and 2 deal with the intelligence cycle
and sources of information.
1. What are the four steps of the
intelligence cycle?
a. production, evaluation, dissemina­
tion, and use
b. planning, collection, processing, and
dissemination
c. collection, evaluation, production,
and dissemination
d. planning, evaluation, processing,
and use
2. In fast moving situations, im­
mediate, detailed and local information
is needed. What sources may be the
only ones used by a division?
a. captured enemy documents and in­
stallations, local civilians and long­
range aerial reconnaissance
b. short­range aerial reconnaissance,
texts, periodicals and technical pa­
pers
c. prisoners of war, reports from front
line troops, and ground and short­
range aerial reconnaissance
d. ground reconnaissance, local civi­
lians, refugees and military re­
turnees, captured enemy material
Second requirement. Multiple­choice exer­
cises 3 and 4 enable you to show your under­
standing of reporting procedures and recon­
naissance in tactical situations.
3. You have been appointed squad
leader and are responsible for insuring
that your men know how to report in­
formation. What items would they in­
clude when reporting information?
a. size, activity, location, unit, time,
and equipment
2­24
b. size, secure, search, silence, segre­
gate
c. what, when, why, how, who
d. shape, activity, location, unit, time,
and equipment
4. During offensive operations,
how often do the engineer battalions
collect information?
a. when specific requirements for in­
formation arise
b. infrequently
c. during lulls in combat or movement
d. continuously
Third requirement. Multiple­choice exer­
cises 5 through 18 emphasize the reconnais­
sance report forms and overlays.
5. You are evaluating your squad's
Engineer Reconnaissance Report. Re­
ferring to figures 1 through 5, Engineer
Reconnaissance Report, where would be
a possible water point location?
a. UT 509686 c. UT 557963
b. UT 512692 d. UT 558680
6. Your squad has been given the
mission of removing the log post ob­
stacle blocking route 132. Referring to
figures 1 through 5, Engineer Reconais­
sance Report, how long will it take in
hours for one squad to remove the ob­
stacle?
a. 0.5 c. 9.0
b. 2.0 d. 24.0
7. You are evaluating your squad's
Road Reconnaissance Report. Refer­
ring to figures 6 and 7, what obstruction
is located at UT 109879?
a. road crater
b. narrow bridge
c. ford
d. underpass
8. Refer to figures 6 and 7, Road
Reconnaissance Report. What critical
feature could you expect to find approxi­
mately 4.4 miles from Fort Belvoir?
a. turn off with deciduous tree conceal­
ment
b. underpass
c. turn off with coniferous tree con­
cealment
d. narrow bridge
9. You are reviewing the informa­
tion on a Bridge Reconnaissance Report.
Your platoon sergeant wants to know
how the bridge is constructed. Refer­
ring to figures 8 and 9, what type of
construction is the bridge?
a. beam c. girder
c. slab d. arch
10. Refer to figures 8 and 9, Bridge
Reconnaissance Report. Pohick Creek
flows in which direction under the
bridge?
a. southwest c. northwest
b. north d. south
11. You have just completed a Tun­
nel Reconnaissance Report. Referring
to figures 10 and 11, what entry did you
make for the length of the tunnel (in
meters)?
a. 60 c. 100
b. 75 d. 150
12. Refer to figures 10 and 11, Tun­
nel Reconnaissance Report. is this
tunnel an obstacle and why?
a. no, the gradient is greater than 7%
b. yes, overhead clearance less than
4.25 m
c. no, meets obstruction criteria
d. yes, traveled way width below stan­
dards, table 3
2­25
13. You are evaluating your squad's
Ford Reconnaissance Report. Refer­
ring to figures 12 and 13, what is the
low water level depth (in meters)?
a. 0.3 c. 6.1
b. 0.5 d. 7.3
14. Refer to figures 12 and 13, Ford
Reconnaissance Report. What must be
done to improve the ford to enable it
to carry loads over 10 tons?
a. construct a causeway
b. repair stream bottom
c. attach cable anchorage to vehicles
d. attach floats to reduce weight
15. Your squad has been given the
mission of ferrying troops. Referring
to figures 14 and 15, Ferry Reconnais­
sance Report, how many passengers can
the ferry carry?
a. 8 c. 85
b. 40 d. 200
16. Refer to figures 14 and 15,
Ferry Reconnaissance Report. The as­
phalt highway approach classification
exceeds the ferry classification by how
much?
a. 5 c. 37
b. 15 d. 40
17. Refer to figure 16, Overlay.
What type of route is VA 617? a. all­weather
b. limited all­weather
c. hard surfaced, most­weather
d. fair­weather
18. Refer to figure 16, Overlay.
What is the length of the ford (in
meters)?
a. 8.2 c. 18.0
b. 17.3 d. 40.0
Fourth requirement. Multiple­choice exer­
cise 19 concerns road classification.
19. You are performing a road re­
connaissance. The road is 20 feet wide
of paving stone surface, bumpy, with a
combined width of traveled way and
shoulders of 32 feet, steep gradients,
and subject to snow blockage. What is
the road classification formula?
a. Bgs 20/32 ft p(T)
b. Bgp 32/20 ft (T)
c. Bsg 20/32 ft p(Ob)
d. Bgp 20/32 ft s(T)
Fifth requirement. Multiple­choice exer­
cises 20 and 21 provide an opportunity for
you to calculate radius of a curve and gra­
dient.
20. One of your men requests that
you check his calculations for radius
of a curve. The length of cord = 71
ft; perpendicular distance from cord to
centerline of road = 6 ft. What is the
radius of the curve (in feet)?
a. 6 c. 74
b. 60 d. 108
21. You have measured the hori­
zontal distance between point A and
point B and determined that it is 150
meters. Point A is 12 meters higher
than point B. What is the gradient from
point B to point A (in percent)?
a. 8 c. 16 b. 12 d. 20
Sixth requirement. Multiple­choice exer­
cise 22 enables you to show your understand­
ing of route classification.
22. You are determining a route
classification. Limiting factors on dif­
ferent sections of the route are: gravel
surface, two lane, 6 meters wide, a mili­
tary load classification of 50, and under
deep snow cover. What is the route
classification?
a. 6mZ50 (S) c. 50Y6 (Ob)
b. 6mY50 (T) d. 6mZ50 (T)
2­26
LESSON 3
HANDTOOLS AND RIGGING
CREDIT HOURS ______________________4
TEXT ASSIGNMENT ___________________Attached memorandum.
MATERIALS REQUIRED ________________None.
LESSON OBJECTIVE __________________To increase your knowledge of the care and
use of handtools; and wire and manila
rope.
______________________________________________________________________________
ATTACHED MEMORANDUM
Section I. GENERAL RIGGING
1. CHARACTERISTICS OF FIBER ROPE
Fiber rope sizes are designated by inches
of diameter up to 5/8 inch, then they are
designated by circumference.
The weight of rope varies with use, weather
conditions, and added preservatives.
Table 1 lists some of the properties of
manila and sisal rope, including strength.
The table shows that the minimum breaking
strength is considerably greater than the
safe working capacity. The difference is
caused by the application of a safety factor.
A safety factor is always used because the
breaking strength of rope becomes reduced
after use and exposure to weather conditions.
In addition, a safety factor is required be­
cause of shock loading, knots, sharp bends
and other stresses which the rope may have
to withstand during its use.
If tables are not available, the rule of
thumb for safe working capacity is used. This
is that the safe working capacity in tons for
fiber rope is equal to the square of the rope
diameter in inches (SWC = Dý). For exam­
ple, the safe working capacity for a 1/2­inch
diameter fiber rope would be 1/2 squared or 1/4,
ton. No attempt should be made to load a
rope to its breaking strength.
2. CARE AND HANDLING OF FIBER ROPE
Fiber rope should be dry when stored and
should be stored in a cool, dry place.
It should be coiled on a spool or hung from
pegs in a way that will allow circulation of
air.
Avoid dragging the rope through sand or
dirt, or pulling the rope over sharp edges
Sand or grit between the fibers of the rope
will cut the fibers and reduce its strength.
Slacken taut lines before they are exposed
to rain or dampness because a wet rope
shrinks and may break.
A frozen rope should not be used until it
is completely thawed; otherwise the frozen
fibers will be broken as they resist bending.
Avoid exposure of fiber rope to excessive
heat and fumes of chemicals.
When handling new rope the protective
burlap covering should not be removed until
the rope is to be used to protect the rope and
prevent tangling (fig. 1). The end of the rope
must be pulled through the center of the coil
from the bottom when uncoiling the rope.
3­1
3. INSPECTING THE FIBER ROPE
The outside condition of the rope will not
show internal deterioration. For this reason
it is necessary to untwist the strands slightly
to inspect the inside of the rope.
Since any weak point in the rope weakens
the entire rope, it is necessary to examine it
in a number of places.
If the rope appears to be satisfactory, pull
out a couple of fibers and attempt to break
them. These fibers should offer considerable
resistance to breakage.
When any unsatisfactory conditions are
found, destroy the rope or cut it into short
pieces.
4. WHIPPING FIBER ROPE
Whipping the ends of the fiber rope pre­
vents the ends from untwisting. (This can
also be accomplished by knotting.)
A rope is whipped by wrapping the end
tightly with a small cord as shown in fig­
ure 2.
3­2
5. CHARACTERISTICS OF WIRE ROPE
The size of wire rope is designated by its
diameter.
The weight of wire rope varies with the
size and the type of construction. Approxi­
mate weights and breaking strengths for cer­
tain sizes are given in table 2.
The strength of a wire rope is determined
by its size, grade, and method of fabrication.
The individual wires may be made of various
materials.
The ultimate or maximum strength of a
wire rope is referred to as the breaking
strength. Since a suitable margin of safety
must be provided when applying a load to a
wire rope, the breaking strength is divided
by an appropriate safety factor (table 3).
As a rule of thumb, the diameter of wire
rope in inches can be squared and multiplied
by 8 to obtain the safe working capacity n
tons.
The proper safety factor depends not only
on the loads applied, but also on the speed
of operation; the type of fittings used for
securing the rope ends; the acceleration and
deceleration; the length of rope; the number,
size, and location of sheaves and drums, the
factors causing abrasion and corrosion.
3­3
6. CARE AND PROPER HANDLING INCREASE
THE LIFE OF THE WIRE ROPE
At the time of fabrication, a lubricant is
applied to wire rope. To renew the lubricant,
a good grade oil or grease can be used.
Used wire rope should be carefully cleaned
of any accumulation of dirt, grit, or other
foreign material. Scraping or steaming will
remove most of the dirt, grit, or rust.
Wire rope should be coiled on a spool for
storage and should be properly tagged as to
size and length.
It should be stored in a dry place to reduce
corrosion, and kept away from harmful
chemicals and fumes.
When loose wire rope is handled, small
loops frequently form in the slack portion of
the rope. If tension is applied to the rope
while these loops are in position, they will not
straighten out but will form sharp kinks. All
of these loops should be straightened out of
the rope prior to applying a load.
After a kink has formed in a wire rope, it
is impossible to remove it and the strength
of the rope is seriously damaged at the point
where the kink occurs. Such a kinked por­
tion should be cut out of the rope before it
is used.
Small loops or twists will form if the rope
is being wound into the coil direction oppo­
site to the lay of the rope. Left lay wire rope
should be coiled in a counterclockwise direc­
tion and right lay wire rope should be coiled
in a clockwise direction.
When removing wire rope from a reel or
coil, it is imperative that the reel or coil ro­
tate as the rope unwinds.
7. CLASSIFICATION OF WIRE ROPE
Wire and strand combinations (fig. 3) vary
according to the purpose for which the rope
is intended. The smaller and more numerous
the wires the more flexible the rope but the
less resistant to external abrasion. Rope
made up of a smaller number of larger wires
is more resistant to external abrasion but is
less flexible.
3­4
Lay (fig.4) refers to the direction of wind­
ing of the wires in the strands and of the
strands in the rope. Both may be wound in
the same direction, or they may be wound in
opposite directions. There are three types of
rope lays:
The most common lay in wire rope is the
right regular lay. Left regular lay is
used where the untwisting rotation of
the rope will counteract the unscrewing
forces in the supported load.
Because of the greater length of exposed
wires, the lang lay assures longer abra­
sion resistance of the wires, less radial
pressure on small diameter sheaves or
drums by the ropes, and less bending
stresses in wire. One disadvantage of
the lang lay is a tendency to kink.
Reverse lay applies to ropes in which the
strands are alternately regular. The use
of reverse lay rope is usually limited to
certain types of conveyors.
8. SEIZING WIRE ROPE
Seizing is the most satisfactory method of
binding the end of a wire rope, although
welding will also hold the ends together sat­
isfactorily. The seizing will last longer and
there is no danger of weakening the wire
through the application of heat. (Wire rope
is seized as shown in figure 5.)
The method for determining the number
of seizings, lengths, and space between is as
follows:
The number of seizings to be applied to
each end equals approximately three
times the diameter of the rope (No. seiz­
ing = 3D).
Example: 3 x 3/4 (dia) = 2 1/4. Use 3
seizings.
Each seizing should be 1 to 1 1/2 times as
long as the diameter of the rope (length
of seizing = 1 1/2D).
Example: 1 1/2 x 3/4 (dia) = 1 1/8. Use
2­inch seizings.
The seizings should be spaced a distance
apart equal to twice the diameter (spac­
ing = 2D).
Example: 2 x 3/4 (dia) = 1 1/2. Use
2­inch spaces.
Note: Always change fraction to next
larger whole number.
9. CUTTING
Wire rope may be cut with a wire rope
cutter, a cold chisel, a hacksaw, bolt clippers
3­5
or an oxyacetylene cutting torch. Before
cutting, the strands must be tightly bound to
prevent unlaying of the rope. Seizing or weld­
ing will secure the ends that are to be cut.
10. KNOTS
The choice of the best knot, bend, or hitch
to use depends on the job it has to do. The
following definitions will aid in understand­
ing the methods of knotting.
Rope­­A rope is a large, stout cord
made of strands of fiber or wire twisted
or braided together.
Line­­A line is a thread, string, cord,
or rope; especially a comparatively
slender and strong cord.
Running end­­The running end is the
free or working end of a rope.
Standing part­­The standing part is
the rest of the rope, excluding the run­
ning end.
Bight­­A bight is a bend or u­shaped
curve in a rope.
Loop­­A loop is formed by crossing the
running end over or under the standing
part forming a circle in the rope.
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Turn­­A turn is placing of a loop
around a specific object such as a post,
rail, or ring with the running end con­
tinuing in a direction opposite to the
standing part.
Round turn­­A round turn is a modi­
fied turn, but with the running end leav­
ing the circle in the same general direc­
tion of the standing part.
Overhand turn or loop­­An overhand
turn or loop is made when the running
end passes over the standing part.
Underhand turn or loop­­An under­
hand turn or loop is made when the run­
ning end passes under the standing part.
Knot­­A knot is an interlacement of the
parts of one or more flexible bodies, as
cordage rope, forming a lump known as
a knot; any tie or fastening formed with
a rope, including bends, hitches, and
splices.
Bend­­A bend is used to fasten two
ropes together or to fasten a rope to a
ring or loop.
Hitch­­A hitch is used to tie a rope
around a timber, pipe, or post so that it
will hold temporarily but can be readily
undone.
11. KNOTS AT THE END OF A ROPE
An overhand knot may be used to prevent
the end of a rope from untwisting, to form
a knot at the end of a rope or to serve as a
part of another knot (fig. 6).
The figure eight knot is used to form a knot
at the end of a rope. The figure eight knot
is used in the end of a rope to prevent the
end from slipping through a fastening or loop
in another rope (fig. 7).
The wall knot (fig. 8) with crown is used to
prevent the end of a rope from untwisting
when an enlarged end is not objectionable.
The wall knot will prevent the rope from
untwisting, but to make a neat round knob,
it should be crowned (fig. 9).
12. KNOTS FOR JOINING TWO ROPES
The square knot (fig. 10) is used for tying
two ropes of equal size together so they will
not slip. The square knot will not hold if the
ropes are wet or if they are of different sizes
3­7
A single sheet bend (fig. 11) has two ma­
jor uses: (1) tying together two ropes of
unequal size and (2) tying a rope to an eye.
This knot will draw tight but will loosen or
slip when the lines are slackened. The single
sheet bend is stronger and more easily untied
than the square knot.
The double sheet bend (fig. 12) has a
greater holding power than the single sheet
bend for joining ropes of equal or unequal
diameter, joining wet ropes, or tying a rope
to an eye. It will not slip or draw tight under
heavy loads. This knot is more secure than
the single sheet bend when used in a spliced
eye. The carrick bend (fig.13) is used for heavy
loads and for joining large hawsers or heavy
rope. It will not draw tight under a heavy
load and is easily untied if the ends are seized
to their own standing part.
13. KNOTS FOR MAKING LOOPS
The bowline (fig. 14) is one of the most
common knots and has a variety of uses, one
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3­9
of which is the lowering of men and material.
It is the best knot for forming a single loop
that will not tighten or slip under strain, and
is easily untied if each running end is seized
to its own standing part. The bowline forms
a loop which may be of any length.
The double bowline (fig.15) forms 3 non­
slipping loops. This knot can be used for
slinging a man. As he sits in the sling, one
loop is used to support his back and the re­
maining two loops support his legs; a notched
board passed through the two loops makes
a comfortable seat known as a boatswains
chair.
The running bowline (fig.16) forms a
strong running loop. It is a convenient form
of running an eye. The running bowline pro­
vides a sling of the choker type at the end of
a single line. It is used when a handling is to
be tied around an object at a point that can­
not be safely reached, such as the end of a
limb.
A bowline on a bight (fig. 17) forms two
nonslipping loops. The bowline on a bight can
be used for the same purpose as a boatswain's
chair. It is used when a greater strength
than that given by a single bowline is neces­
sary, when it is desirable to form a loop at
some point in a rope other than at the end,
or when the end of a rope is not accessible.
The bowline on a bight is easily untied, and
can be tied at the end of a rope by doubling
the rope for a short section.
3­10 A Spanish bowline (fig. 18) can be tied at
any point in a rope, either at a place where
the line is double or at an end which has been
doubled back. The Spanish bowline is used
in rescue work or to give a two­fold grip for
lifting a pipe or other round objects in a
sling.
The French bowline (fig. 19) is sometimes
used as a sling for lifting injured men. When
used for this purpose, one loop is used as a
seat and the other loop is put around the
body under the arms. The weight of the in­
jured man keeps the two loops tight so that
he cannot fall out. It is particularly useful
as a sling for an insensible man. The French
bowline may also be used where a man is
working alone and needs both hands free.
The two loops of this knot can be adjusted to
the size required.
A speir knot (fig. 20) is used when a fixed
loop, a nonslip knot, and a quick release are
required. It can be tied quickly and released
by a pull on the running end.
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3­12
A figure eight with an extra turn (fig. 21)
can be used to tighten a rope. This knot is
especially well suited for tightening a one­
rope bridge across a small stream.
A catspaw (fig. 22) can be used for fasten­
ing an endless sling to a hook, or it can be
made at the end of a rope for fastening the
rope to a hook.
14. HITCHES
The halt hitch (A, fig. 23) is used to tie a
rope to a timber or to a larger rope. It will
3­13
hold against a steady pull on the standing
part of the rope, but is not a secure hitch.
It is frequently used for securing the free
end of a rope, and is an aid and the founda­
tion of many knots.
Two half hitches (B, fig. 23) are especially
useful for securing the running end of a rope
to the standing part. If the two hitches are
slid together along the standing part to form
a single knot, the knot becomes a clove hitch.
The hitch used for fastening a rope to a
pole, timber, or spar is the round turn and
two half hitches (fig. 24).
The timber hitch (fig. 25) is used for mov­
ing timber or poles. This hitch is excellent
for securing a piece of lumber or similar ob­
ject. A timber hitch and half hitch (fig. 26) are
combined to hold heavy timber or poles when
they are being dragged.
The clove hitch (fig. 27) is one of the most
widely used knots. It is used to fasten a rope
to a timber, pipe, or post. It is also used for
making other knots. This knot puts very
little strain on the fibers when the rope is put
around an object in one continuous direction.
The clove hitch can be tied at any point in a
rope. If there isn't constant tension on the
rope, another loop (round of the rope around
the object and under the center of the clove
hitch) will permit a tightening and slacken­
ing motion of the rope.
The rolling hitch (fig. 28) is used to a se­
cure a rope to another rope, or fasten it to
a pole or pipe so that the rope will not slip.
This knot grips tightly, but is easily moved
along a rope or pole when strain is relieved.
The telegraph hitch (fig. 29) is a very use­
ful and secure hitch which is used to hoist
or haul posts and poles.
The scaffold hitch (fig. 30) is used to sup­
port the end of a scaffold plank with a single
rope. It prevents the plank from tilting.
3­14
The blackwall hitch (fig. 31) is used for
fastening a rope to a hook. It is generally
used to attach a rope temporarily to a hook
or similar object in derrick work. Human life
and breakable equipment should never be en­
trusted to the blackwall hitch.
The girth hitch (fig. 32) is used in tying
suspender ropes to hand ropes in the con­
struction of expedient foot bridges.
A sheepshank (fig. 33) is a method of
shortening a rope, but it also may be used to
take the load off a weak spot in the rope. It
3­15
is only a temporary knot unless eyes are
fastened to the standing part on each end.
The fisherman's bend (fig. 34) is an excel­
lent knot for attaching a rope to a light an­
chor, a ring, or a rectangular piece of stone.
It can be used to fasten a rope or cable to a
ring or post or where there will be slacken­
ing and tightening motion in the rope.
3­16 The harness hitch (fig. 35) forms a nonslip­
ping loop in a rope. It is often employed by
putting an arm through the loop, then plac­
ing the loop on the shoulder and pulling the
object attached to the rope. The hitch is tied
only in the middle of a rope. It will slip if
only one end of the rope is pulled.
15. KNOTS FOR TIGHTENING ROPE
The butterfly knot (fig. 36) is used to pull
taut a high line, handline, tread rope for foot
bridges, or similar installations. Use of this
knot will provide the capability to tighten a
fixed rope when mechanical means are not
available. (The harness hitch (fig. 35) can
also be used for this purpose.)
3­17
3­18
3­19
The baker bowline (fig. 37) may be used
for the same purpose as the butterfly knot
(fig. 36) and for lashing cargo. When used
to lash cargo, secure one end with two half
hitches, pass the rope over the cargo and tie
a baker bowline (fig. 37), then secure the
lashing with a slippery half hitch. To release
the rope, simply pull on the running end.
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3­21
16. LASHINGS
The square lashing (fig. 38) is used to lash
two spars together at right angles to each
other. To tie a square lashing, begin with a
clove hitch on one spar and make a minimum
of 4 complete turns around both members.
Continue with two frapping turns between
the vertical and the horizontal spar to tighten
the lashing. Tie off the running end to the
opposite spar from which you started with
another clove hitch to finish the square lash­
ing.
The shears lashing (fig. 39) is used to lash
2 spars together at one end to form an ex­
pedient device called a shears. This is done
by laying 2 spars side by side, spaced approx­
imately 1/3 the diameter of a spar apart, with
the butt ends together. The shears lashing
is started a short distance in from the top of
one of the spars by tying the end of the rope
to it with a clove hitch. Then 8 tight turns
are made around both spars above the clove
hitch. The lashing is tightened with a mini­
mum of 2 frapping turns around the 8 turns.
The shears lashing is finished by tying the
end of the rope to the opposite spar from
which you started with another clove hitch.
3­22
Block lashing (fig. 40) is used to tie a
tackle block to a spar. First, 3 right turns
of the rope are made around the spar where
the tackle block is to be attached. The next
2 turns of the rope are passed through the
mouth of the hook or shackle of the tackle
block and drawn tightly. Then 3 additional
taut turns of the rope are put around the
spar above the hook or shackle. The block
lashing is completed by tying the 2 ends of
the rope together with a square knot. When
a sling is supported by a block lashing, the
sling is passed through the center 4 turns.
17. KNOTS FOR WIRE ROPE
Under special circumstances when wire
rope fittings are not available and it is neces­
sary to fasten wire rope by some other man­
ner, certain knots can be used. In all knots
made with wire rope, the running end of the
rope should be fastened to the standing part
after the knot is tied.
The fisherman's bend, clove hitch, and
carrick bend can be used for fastening wire
rope.
3­23
18. SPLICES
Splices are used to join fiber rope or wire
rope. The splices are as strong as the rope
itself. There are four general types of splices
in fiber rope­­long, back, short, and eye
splices. The methods of making all four types
of splices are similar. They generally con­
sist of three basic steps­­unlaying the
strands of the rope, placing the rope ends
together, and interweaving the strands and
tucking them into the rope. Table 4 shows
the length of rope to be unlaid on each of the
two ends of the ropes, and the amount of
rope required for the tuck.
The short and long splices are very similar.
The short splice (fig. 41) causes an increase
in the diameter of the rope for a short dis­
tance and can be used only where this in­
crease in diameter will not affect operations.
However, the long splice (fig. 42) does not
increase the diameter and a skillfully made
long splice will run through sheaves. Both
splices are as strong as the rope itself.
Eye or side splice (fig. 43) is used for mak­
ing a permanent loop in the end of a rope.
This splice is also used to splice one rope into
the side of another.
The end of a rope is back spliced to prevent
unlaying. If a slight enlargement of the end
is not objectionable, a crown splice (fig. 44)
should be used.
19. ATTACHMENTS FOR WIRE ROPES
Most attachments give maximum strength
when the rope is connected with another rope,
hook, or ring (fig. 45).
End fittings may be placed directly on the
wire rope (fig. 46). There are three types of
end fittings which may be easily changed.
Clips (fig. 47) are reliable and durable.
They are used for making eyes in ropes.
The clips should be placed about six rope
diameters apart for best service. The
number of clips to be installed is equal
to three times the diameter plus one.
Clamps (fig. 48) can be used with or
without a thimble to make an eye. The
clamp has 90% the strength of the rope.
A wedge socket (fig. 49) end fitting is
used when it may be necessary to change
the fitting at frequent intervals. The
fitting is about two­thirds as strong as
the rope itself.
20. SLINGS
Slings may be made up of fiber rope, wire
rope, or chain. Fiber rope makes good sling
material because of its flexibility, but it is
more easily damaged by any sharp edges on
the material hoisted. Wire rope is widely
used because of its strength and flexibility.
Chain slings are used for lifting very hot
items or items with sharp metal edges.
There are three basic types of slings.
The endless sling (fig. 50) is made by
splicing the ends of a wire rope together, or
by inserting a cold shut link in a chain.
A single sling (fig. 51) can be made by
forming an eye in each end of a piece of fiber
rope or wire rope. In some instances the ends
of a wire rope are spliced into eyes around
thimbles and one eye is fastened to a hook
with a shackle.
Combination slings (fig. 52). Single
slings can be combined into bridle slings, bas­
ket slings, and choker slings to lift virtually
any type of load. Either two or four single
slings can be used in a given combination.
Where greater length is required, two of the
single slings can be combined into a longer
single sling.
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3­25
It is very important that slings strong
enough to lift the load be selected. Tables 5
and 6 list the safe working loads of manila
and wire rope slings under various lift con­
ditions.
Slings should be inspected regularly to pre­
vent injury to personnel or damage to equip­
ment.
21. BLOCKS AND TACKLE
A block is essentially a wood or metal
frame containing one or more rotating pul­
leys called sheaves.
3­26
3­27
3­28
Tackle is an assembly of ropes and blocks
used to gain the desired mechanical advan­
tage. Simple tackle is one or more blocks
reeved with a single rope (fig. 53). Com­
pound tackle is two or more blocks reeved
with one or more ropes (fig. 54)
22. ANCHORS
When heavy loads are handled with tackle,
it is necessary to have some means of anchor­
age. Wherever possible, natural anchorages
should be used for speed and economy. Tem­
porary anchorages include pickets, rock an­
chors, holdfasts (fig. 55), and deadmen (fig.
56). Permanent anchorages may be made up
of steel anchors set in concrete or fastened
to permanent structures.
3­29
23. GUYLINES
Guylines should always be fastened to an­
chorages at a point as near to the ground as
possible. The angle at which the guyline pulls
on an anchor should be as nearly parallel to
the ground as possible to avoid pulling the
anchorage out of the ground. It is better to
3­30
3­31
link two or more anchors together in an an­
chorage than to use a single anchor, because
the multiple anchors spread the load against
the ground. In linking anchors together, a
point high on one anchor should be secured
to a point near the ground on the anchor be­
hind it.
(Figure 54 on page 3­33)
3­32
Section II. LIFTING AND MOVING LOADS
With an elementary knowledge of rigging,
rope, tackle, and timber, devices can be made
in the field to assist greatly in lifting or mov­
ing heavy loads. There are a variety of devices
you can use. The four most commonly used
are the gin pole, tripod, shears, and boom.
3­33
24. GIN POLE
The gin pole (fig. 57) consists of an upright
spar which is guyed at the top to maintain it
in vertical or nearly vertical position, and
equipped with suitable hoisting tackle.
The proper method for rigging a gin pole
is as follows: Lay out the pole with the base
at the spot where it is to be erected. In order
to make provisions for the guylines and
tackle blocks, place the gin pole on cribbing
for ease of lashing (fig. 58). The procedure
is as follows:
Make a tight lashing of eight turns of
fiber rope about 1 foot from the top of
the pole, with two of the center turns
engaging the hook of the upper block of
the tackle. Secure the ends of the lash­
ing with a square knot. Nail wooden
cleats (boards) to the pole flush with the
lower and upper sides of the lashing to
prevent the lashing from slipping.
Lay out two guy ropes, one for the side
guylines and one for the fore and back
guylines. Each rope should be four times
the length of the gin pole.
In the center of each guy rope, form a
clove hitch over the top of the pole next
to the tackle lashing to form two guys,
and be sure the guylines are alined in the
direction of their anchors.
3­34
Lash a block to the gin pole about 2 feet
from the base of the pole, the same as
was done for the tackle lashing at the
top, and place a cleat above the lashing
to prevent slipping. This block serves
as a leading block on the fall line which
allows a directional change of pull from
the vertical to the horizontal. A snatch
block is the most convenient type to use
for this purpose.
Reeve the hoisting tackle and use the
block lashed to the top of the pole so
that the fall line can be passed through
the leading block at the base of the gin
pole.
Drive a stake about 3 feet from the base
of the gin pole. Tie a rope from the stake
to the base of the pole below the lashing
on the leading block and near the bottom
3­35
of the pole. This is to prevent the pole
from skidding while it is being erected.
Check all lines to be sure that they are
not snarled. Check all lashings to see
that they are made up properly, and see
that all knots are tight. Check the hooks
on the blocks to see that they are moused
properly. The gin pole is now ready to
be erected.
The proper procedure for erecting a gin
pole is as follows: A gin pole 40 feet long
may be raised easily by hand, but longer poles
must be raised by supplementary rigging or
power equipment. The number of men needed
depends on the weight of the pole. The pro­
cedure is as follows:
Dig a hole about 2 feet deep for the base
of the gin pole.
String out the guys to their respective
anchorages and assign a man to each
anchorage to control the slack in the
guyline with a round turn around the
anchorage as the pole is raised. If it
has not been done already, install an
anchorage for the base of the pole.
If necessary, the tackle system utilized
to raise and lower the load may be used
to assist in raising the gin pole, but the
attaching of an additional tackle system
to the rear guyline is preferable. Attach
the running block of the rear guyline
tackle system to the rear guyline the
end of which is, at this point of erection,
near the base of the gin pole. The fixed
or stationary block is then secured to
the rear anchor. The fall line should
come out of the running block to give
greater mechanical advantage to the
tackle system. The tackle system is
stretched to the base of the pole before
it is erected to prevent the choking of
the tackle blocks during the erection of
the gin pole.
Keep a slight tension on the rear guyline
and on each of the side guylines, and then
haul in on the fall line of the tackle
system while eight men (more for larger
poles) raise the top of the pole by hand
until the tackle system can take control.
The rear guyline must be kept under
tension to prevent the pole from swing­
ing and throwing all of its weight on one
of the side guys.
When the pole is in its final position,
approximately vertical or inclined as de­
sired, make all guys fast to their an­
chorages with the round turn and two
half hitches. It frequently is desirable
to double the portion of rope used for
the half hitches.
Open the leading block at the base of the
gin pole and place the fall line from the
tackle system through it. When the lead­
ing block is closed the gin pole is ready
for use. If it is necessary to move (drift)
the top of the pole without moving the
base, it should be done when there is
no load on the pole, unless the guys are
equipped with tackle.
25. TRIPOD
The tripod (fig. 59) consists of three legs
lashed at the top. Its advantage over other
devices is its stability. Its disadvantage is
that the load can only be moved up and down.
The proper method for lashing a tripod is
as follows (fig. 60):
The material used for lashing can be
fiber rope, wire rope, or chain. Metal
rings joined with short chain sections
and large enough to slip over the top
of the tripod legs also can be used. The
method described below is for fiber rope
1 inch in diameter or smaller. Since the
strength of the tripod is affected directly
by the strength of the rope and the lash­
ing used, more turns than described be­
low should be used for extra heavy loads
and fewer turns can be used for light
loads.
Select three spars of approximately equal
size and place a mark near the top of
each spar to indicate the center of the
lashing.
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Lay two of the spars parallel with their
tops resting on a skid or block and a
third spar between the first two, with
the butt in the opposite direction and
the lashing marks on all three in line.
The spacing between spars should be
about one­half the diameter of the spars.
Leave the space between the spars so
that the lashing will not be drawn too
tight when the tripod is erected. With a 1­inch rope, make a clove hitch
around one of the outside spars about 4
inches above the lashing mark and take
eight turns of the line around the three
spars. Be sure to maintain the space
between the spars while making the
turns.
Finish the lashing by taking two close
frapping turns around the lashing be­
tween each pair of spars. Secure the
end of the rope with a clove hitch on the
center spar just above the lashing. Frap­
ping turns should not be drawn too tight.
The proper procedures for erecting a tripod
as follows:
The legs of a tripod in its final position
should be spread so that each leg is
equidistant from the others. This spread
should not be less than one­half nor more
than two­thirds of the length of the
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legs. Chain, rope, or boards should be
used to hold the legs in this position. A
leading block for the fall line of the
tackle may be lashed to one of the legs.
Raise the tops of the spars about 4 feet,
keeping the base of the legs on the
ground.
Cross the two outer legs. The third or
center leg then rests on top of the cross.
With the legs in this position, pass a
sling over the cross so that it passes
over the top or center leg and around
the other two.
Hook the upper block of a tackle to the
sling and mouse the hook.
Continue raising the tripod by pushing
in on the legs as they are lifted at the
center. Eight men should be able to
raise an ordinary tripod into position.
When the tripod legs are in their final
position, place a rope or chain lashing
between the legs to hold them from shift­
ing.
26. SHEARS
Shears (fig. 61) are easily assembled and
require only two guys. The shear legs may
be round poles, timbers, heavy planks, or
steel bars, depending on the material at hand
and the purpose of the shears. They are
adaptable to working at an inclination from
the vertical. In addition to their hoisting and
lifting capabilities, shears are used extensive­
ly as towers for cableways and in floating
bridge operations.
3­38
The procedure for lashing the shears is as
follows:
The spread of the legs should equal about
one­half the height of the shears. The
maximum allowable drift (inclination) is
45ø. Tackle blocks and guys for shears
are essential. The guy ropes can be se­
cured to firm posts or trees with a turn
of the rope so that the length of the
guys can be adjusted easily.
Lay two timbers together on the ground
in line with the guys, with the butt ends
pointing toward the back guy and close
to the point of erection.
Place a large block under the tops of the
legs just below the point of lashing, and
insert a small spacer block between the
tops at the same point. The separation
between the legs at this point should be
equal to one­third the diameter of one
leg, to make handling of the lashing
easier.
With sufficient 1­inch rope for 14 turns
around both legs, make a clove hitch
around one spar, and take 8 turns around
both legs above the clove hitch. Wrap
the turns tightly so that the lashing is
made smooth and without kinks.
Finish the lashing by taking two frap­
ping turns around the lashing between
the legs and securing the end of the
rope to the other leg just below the
lashing. For handling heavy loads, the
number of lashing turns is increased.
The proper procedure for the erecting of
shears is as follows:
Holes should be dug at the points where
the legs of the shears are to stand. In
case of placement on rocky ground, the
base for the shears should be level. The
legs of the shears should be crossed and
the butts placed at the edges of the holes.
With a short length of rope, make two
turns over the cross at the top of the
shears and tie the rope together to form
a sling. Be sure to have the sling bearing
against the spars and not on the shears
lashing entirely.
Reeve a set of blocks and place the hook
of the upper block through the sling.
Secure the sling in the hook by mousing.
Fasten the lower block to one of the legs
near the butt, so that it will be in a
convenient position when the shears have
been raised, but will be out of the way
during erection.
If the shears are to be used on heavy
lifts, another tackle is rigged in the back
guy near its anchorage. The two guys
should be secured to the top of the shears
with clove hitches to legs opposite their
anchorages above the lashing.
Several men (depending on the size of
the shears) should lift the top end of
the shear legs and "walk" them up by
hand until the tackle on the rear guyline
can take effect. After this, the shear legs
can be raised into final position by haul­
ing in on the tackle. Secure the front
guyline to its anchorage before raising
the shear legs and keep a slight tension
on this line to control movement.
The legs should be kept from spreading
by connecting them with rope, chain, or
boards. It may be necessary, under some
conditions, to anchor each leg of the
shears during erection to keep the legs
from sliding in the wrong direction.
27. BOOM DERRICK
Booms (fig. 62) are used on gin poles to
lift loads where a long horizontal reach is
required. For medium loads, the boom can
swing about the gin pole.
The methods of rigging and erecting the
boom derrick is as follows:
Rig a gin pole as described previously,
but lash another block about 2 feet below
the tackle lashing at the top of the pole.
Reeve the tackle so that the fall line
comes from the traveling block to the
end of the boom after the mast is erected.
3­39
Erect the mast in the manner described
previously, but pass the fall line of the
tackle through the extra block at the
top of the pole before erection to increase
the mechanical advantage of the tackle
system.
Select a boom with the same diameter
and not more than two­thirds as long as
the mast. Spike two boards to the butt
end of the boom and lash them with
rope, making a fork. The lashing should
be made with a minimum of sixteen
turns and tied off with a square knot.
Drive wedges under the lashing next to
the cleats to help make the fork more
secure.
Spike cleats to the mast about 4 feet
above the resting place of the boom and
place another block lashing just above
these cleats. This block lashing will sup­
port the butt of the boom. If a separate
tackle system is ripped up to support
the butt of the boom, an additional block
lashing should be placed on the boom
just below the larger lashing to secure
the running block of the tackle system.
If the boom is light enough, manpower
may be used to lift the boom in place on
the mast through the sling which will
support it. The sling consists of 2 turns
of rope with the ends tied together with
a square knot. The sling should pass
through the center 4 turns of the block
lashing on the mast and should cradle
the boom. On heavier booms, the tackle
system on the top of the mast can be
used to raise the butt of the boom to the
desired position onto the mast.
Lash the traveling block of the mast
tackle to the top end of the boom and
lash the standing block of the boom
tackle at the same point. Reeve the
boom tackle so that the fall line comes
from the standing block and passes
through the block at the base of the
mast. The use of the leading block on
this fall line is optional, but when han­
dling heavy loads, more power may be
applied to a horizontal line leading from
the block with less strain on the boom
and guys.
Section III. ENGINEER HANDTOOLS
28. PIONEER TOOLS
The single bit ax is a chopping tool used
to fell or prune trees, to cut or trim logs and
heavy brush, and to split and cut wood. The
head has a flat face on one end. A blade,
called a "bit", with a slightly fanshaped cut­
ting edge, is at the other end. Before using
the ax, always clear the work area of ma­
terial that might deflect the ax blade. While
using the ax, the user's body weight should
be distributed evenly on both legs, with knees
set but not tense. The feet should be spread
apart at a comfortable distance to retain
balance, while the body should be relaxed and
free to swing and bend at the waist.
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The brush hook is used where it is not
practical to use the ax, for cutting under
brush, shrubs, and branches. To use the
brush hook on a tree branch lift the curve of
the hook above the branch and make short,
chopping strokes downward against the sur­
face of the branch. In cutting small brush,
the brush hook is swung horizontally like a
scythe, with the hooked portion used to keep
the brush from bouncing away from the cut­
ting edge.
The adz is a chopping tool used for hewing
and smoothing lumber or logs, where a great
deal of wood or bark is to be removed. The
adz is a form of ax on which the edge of
the blade is at a right angle to the handle.
At one end of the adz's curved head is a flat
surface and the eye. At the other end is the
cutting blade. The cutting edge of the blade
is 3 1/2 to 4 1/2 inches wide, and is beveled on
the inside of the curve only. To use the adz,
first clear the work area of branches and
debris, and while using it do not let wood
chips pile up on the work surface. Block the
timber to be worked on so it cannot slip,
slide, or roll. Straddle the timber and grip
the adz handle with both hands. The left
hand should be near the handle's end and the
right hand held on the handle from 12 to 15
inches below, while keeping the hands in
approximately the same position on the han­
dle. When using the adz, the right hand does
not slide toward the left hand as in swinging
the ax, because the right hand must be in a
position to keep control of the adz head at all
times. Since the tool's cutting edge operates
close to the feet and legs of the adz user,
sliding the right hand to the end of the handle
would leave the adz blade free to be deflected
toward the user, possibly causing injury.
Large crosscut saws are used for heavy
work such as felling trees, cutting large trees
into logs, and sawing heavy timbers. The
large crosscut saws have a high grade steel
blade with two types of teeth, known as cut­
ters and rakers. The cutters can be the
crosscut or ripping type of tooth, and are
slightly longer than the rakers. The cutters
do the cutting and the rakers chisel out and
remove chips from the kerf.
The one­man crosscut saw is operated like
the handsaw, except that the left hand helps
to guide and pull the blade with the handle at­
tached to the saw back, at the saw's heel end.
The two­man crosscut saw must be op­
erated by two men. It is moved across the
wood by pulling action only. One man pulls
the blade toward himself as far as it will go,
while the other man guides the saw. Then
the procedure is reversed, with the first man
doing the guiding and the second man pulling
the saw toward himself.
The stillson pipe wrench is designed for
use on round objects like pipe, shafting, and
rods, where a smooth surface requires a
wrench that can take a bite on the work to
turn it.
In using this wrench, the grip on the work
is increased by pressing the wrench handle
downward in the direction of the jaw opening.
To use the pipe wrench, turn the adjusting
nut so the jaw opening is slightly larger than
the object to be gripped. Place the work as
far back into the jaw as possible, and tighten
the adjusting nut so the movable jaw fits
snugly on the object to be turned. Apply
force to the back of the handle so the wrench
is turning in the direction of the jaw opening.
Applying pressure to the opposite direction,
toward the adjusting nut, will loosen this
wrench's grip. Never use the pipe wrench
on nuts or bolts, because the wrench's hard
teeth will make nuts or bolts unusable by
chewing them up.
Bars are heavy steel tools used to lift and
move heavy objects, and to pry where lever­
age is needed.
In moving heavy objects or prying with a
bar, it should be used in a position where the
weight of the user's body is exerted down­
ward on the long section of the lever. When
possible, use a block or other object as a
fulcrum behind the bar, near the spot where
the bar's point is wedged under the object
to be moved. In ripping or tearing apart
3­41
roughly with a bar, wedge it under the object
to be ripped off, and jerk the hand end up
and down to loosen the object. When using a
bar for prying, always be sure the point is
securely set under the object being worked
on, so the bar will not slip and damage the
work or cause injury.
The wrecking bar is used to pull nails or
spikes, to open heavy crates, and to do demoli­
tion or wrecking work. The wrecking bar is
a shaft of tough steel with a gooseneck claw
end for removing large nails and spikes and
for prying. The other end is called the pinch
point and is tapered down to resemble a
chisel. The pinch point can be straight, slight­
ly angled, or offset. The size of the bars
found in the carpenter sets averages from 30
to 48 inches, with a diameter of 1/2 to 1 1/8
inches.
The crowbar is used for heavy prying (lift­
ing) and for moving heavy timbers and other
large objects for short distances. It can also
be used for loosening rock formations, as a
lever for moving rails, and for breaking up
hard earth when digging. The crowbar that
is issued with pioneer tool sets is a steel bar,
about 5 feet long, tapered to a rounded point
at the end where it is usually held. There is
a pinch point with a chisel­like, squared­off
wedge, at the other end. Some crowbars
have the pinch point set at a slight angle.
The pinchbar is used in light ripping and
prying jobs. The one issued with pioneer sets
is a steel bar, from 26 to 36 inches long, with
a tapered point at one end and a chisel­like
pinch point at the other. The pinch point is
sometimes bent slightly. Some pinchbars
have a short claw at the tapered end. This
bar ranges from 1/2 to 1 inch in diameter.
Jacks are used to raise or lower work or
heavy loads short distances. Jacks are also
used to lift the side or the end of a vehicle.
Jacks are metal tools that are operated
through a rack bar or screw or operated
hydraulically. They are available to handle
loads of from 1 1/2 to 100 tons. The jack
issued with pioneer tool sets are both the
screw type and the hydraulically operated
type and have a lifting capacity of 12 tons.
Climbing tools are used for scaling poles
and trees when erecting power lines and gin
poles, for clearing and topping trees, and for
similar operations.
The climbing tools consist of a safety belt,
a safety strap, and the leg iron set with spurs
or gaffs. The safety belt is an adjustable
leather belt that has loops in which to carry
tools. It also has two D­rings fastened to it
for holding the safety strap. The safety strap
is a leather strap with metal snaphooks on
each end, for hooking into the D­rings of the
safety belt. The leg irons are called the tree
and pole climbers and consist of flattened
metal bars that are curved at one end to fit
under the foot arch, with the straight portion
continuing along the inside of the lower leg.
Leather straps secure these climbers to the
leg and ankle. On the leg iron, pointing down­
ward at the arch, is a spur (gaff) which sticks
into the surface of the tree or pole and carries
the weight of the wearer's body when climb­
ing. In some climber sets, this metal gaff is
detachable and two sets of gaffs are included.
29. CARPENTER'S TOOLS
Handsaws are tools with thin, flat steel
blades that have a row of spaced notches
called "teeth" along one edge and are made
of special steel that is hardened, tapered,
tempered, and ground. The blade is fastened
to some type of handle. Saws are available
in different types and sizes. Each type of
material that can be sawed demands a special
type of saw for best results. Factors to be
considered in selecting the correct saw for a
job include type and hardness of the material
to be cut, its grain or composition, how long
a cut will be, whether it will be an inside or
outside cut, and specific physical properties of
the material (as green, wet, new, or used
lumber).
The crosscut saw is designed to cut across
the grain of the wood. Its teeth are con­
structed so they have bevels and resemble a
row of small triangular knives. On a crosscut
saw each side of the tooth is filed to cutting
edge like a knife. Crosscut saws and ripsaws
have the same general appearance, except
that their teeth differ in shape and bevel.
3­42
The ripsaw is designed to cut with the grain
of the wood. On a ripsaw, each tooth is filed
straight across to a sharp square edge like
a little chisel. The teeth of the ripsaw are a
series of little chisels set in two parallel rows
that overlap each other for cutting with the
grain of the wood.
The nested saws are used to cut along
curved lines, to start cuts for larger saws,
and to make cuts inside a board or partition
where sawing must start from a drilled hole
or small opening. The nested saws consist
of a wooden handle to which three different
blades can be attached for making up the
three saws known as the keyhole, compass,
and plumber's saws. A slotted end at the
heel of each blade slips into the pistol­grip
type handle, where a thumbnut fastens the
blade in place.
The hacksaw is designed to cut almost any
size or shape of metal object. Hacksaws
come in sizes from 8 to 12 inches in length,
with blades from 14 to 32 points to the inch.
Two types of hacksaw blades are made: hard
and flexible. All of the metal in a hard blade
is tempered, while the flexible blade is hard­
ened or tempered only along the tooth edge.
The 18­point flexible blade, which is issued
with pioneer tool sets, is considered best for
general use.
Planes are smoothing tools used to true
the edges or surfaces of wood, where a
finished surface or close­fitting joints are re­
quired. Planes are made to do specific jobs
and are found in many forms.
Block planes are the smallest type, aver­
aging 6 inches in length, and are generally
operated with one hand. They are used pri­
marily to make small cuts, where the cut
must be made across the grain of the wood,
and to square edges. The cutting edge bevel
of the block plane is used with its bevel up,
away from the work.
Bench planes are normally used to cut with
the grain of the wood. Common types are
the smoothing plane (5 1/2 to 10 inches) with
a straight cutting edge used for finishing
purposes, the jack plane (11 to 15 inches)
for all­purpose planing and the jointer plane
(20 to 24 inches) for truing finished surfaces.
The chalkline is used to lay out a straight
line between two points that are too far apart
to permit use of a square or straightedge for
drawing a line. It can be used for such jobs
as staking out foundations; laying brick;
alining walls, forms, and posts; and marking
long boards for sawing. To use the chalkline,
first mark the spots between which a straight
line is desired, by stakes, nails, or other ob­
jects. Tie the chalkline to the object marking
the spot, or have a man hold it there. Hold
the chalk in the palm of the hand, then draw
the chalkline over the chalk while moving
toward the other layout point. Fasten the
chalkline, now coated with chalk, to the other
layout point, or hand it to the man stationed
there, and make sure the line is stretched
tightly between the points. Grasp the line
midway between both points and pull it away
from the work surface at a right angle to the
work surface. Release the line from the
fingers so it will snap downward to deposit
chalk on the work surface in a straight line.
The carpenter's level is used to determine
whether a surface is truly horizontal or verti­
cal. It is a long, rectangular body of wood
or metal that is cut away on its side and near
the end to hold small glass tubes. These glass
tubes are almost entirely filled with a non­
freezing liquid which leaves a small bubble
free to move as the level is moved. All sides
of this level are true­surface edges. The glass
tubes have hairline marks at equal distances
from the middle of the tube to mark the upper
position of the bubble when the surface on
which the tool rests is level. To test the
levelness of a surface, place the carpenter's
level on the work surface. Check the glass
tube that is horizontal with the surface being
tested, to see if the bubble is centered evenly
between the hairline guides on the tube. If
the bubble is not centered, lower or raise one
side of the work surface enough to center the
bubble. Then turn the level around, end to
end, and doublecheck the reading to be sure
the level is accurate. To plumb an object, hold
the level flat against the vertical surface to
be plumbed and follow the same steps used
3­43
for testing levelness, using the glass tube that
is horizontal.
The line level is used to check the level of
a line between two points, as in checking the
floor of an excavation, or to check a line that
is to be an elevation guide. It is a short level
with a hook at each end for hanging onto a
line.
To use the line level, stretch a cord tautly
between the two points so the cord is at the
exact elevation and lies along the desired
working line. Hang the level by its hooks
about midway between the two end points
and adjust the line at each end so the bubble
in the glass tube lies between the hairlines.
A plumb bob is used to obtain a true verti­
cal line for checking whether uprights or
walls are truly vertical.
To use the plumb bob, fasten it to a cord
that is long enough to extend the tool from
the checking point to the spot where a read­
ing must be made. Fasten the cord to the
top checking point and let the plumb bob
hang freely on the cord. The spot above
which the plumb bob's point stops is the true
vertical with the spot at the other end of the
cord. If breezes or other air circulation keep
the plumb moving, it may be necessary to
shield it with the body or a board to get an
accurate reading.
The carpenter's square (fig. 63) is used to
measure and mark lumber, to test the square­
ness and flatness of wood, and to make cal­
culations with the aid of its graduations and
tables. This square, sometimes called a fram­
ing square because it is especially useful in
structure framing, is an L­shaped, flat piece
of steel. The longer portion is called the body
or blade and is 24 inches long. The shorter
portion is 16 inches long and is called the
tongue. Graduations in inches and fractions
of inches are found on both sides and on the
inside and outside edges of this square.
Several scales and tables are on the square,
for figuring lengths of lumber and laying out
work to dimension.
Place the square blade on the board with
the heel at the end of the board, and the 24­
inch body lying along the length of the board.
Mark the spot where the body ends, then
move the heel end over to this spot and mark
the next 24­inch segment at the end of the
body. Continue moving the square along the
length of the board, making a mark every 24
inches until the measurement is completed.
Measuring the distance for setting studs at
the normally used 16­ or 24­inch centers is
particularly easy with the square, because the
lengths of its body and tongue are designed
for this purpose.
To mark a board at a right angle to its
edge, place the inner edge of the square's
body along the edge of the board. The tongue
will be at a right angle to the edge of the
board and the line can be drawn along the
tongue edge.
To test a board for squareness, place the
inner edge of the body along the edge of the
board, with the edge of the tongue at the
end of the board. If the board is square, there
will be no light showing through between the
inner edges of the square and the edges of
the board.
To test whether a board is warped (not
flat), set the outer edge of the body or tongue
along both diagonals of the board. If the
board is not flat, the edge of the square will
not touch the board along its entire length.
Along the outer edges of both sides of this
square's body and tongue are inch markings
which are divided into graduations of 1/32,
1/16, 1/12, 1/10, 1/8, and 1/4. These gradua­
tions are used in measuring and in laying out
work.
The tables and scales on the carpenter's
steel square (essex table, hundredths scale,
rafter or framing table, brace table, octagon
scale) are used to make quick calculations.
Combination square (fig. 63) combines the
equivalent of many tools such as the straight­
edge, plumb, level, outside try square, inside
try square, marking gage, depth gage, and
miter square. It is a foot­long steel blade
with a metal head which can be moved and
clamped to any desired position along the
3­44
blade. The head has machined edges at 45­
and 90­degree angles with the blade and is
fitted with a vial or tube in the carpenter's
level and a steel scriber or awl. To set the
head of this square to any position on the
blade, loosen the knurled nut and move the
head to the desired position, then tighten the
nut.
The combination square is used to lay out
and mark angles, as a depth gage, and for
plumbing and squaring purposes.
The try square (fig. 63) has many uses. It
will serve as a guide for marking lines at right
angles to an edge or surface; to test straight­
ness and squareness of edges, faces, and ends
of small boards; to check an edge or surface
to determine whether it is the same width
or thickness throughout its length; to serve
as a scale for laying out work on small pieces
of lumber when cutting and framing; and
to test inside or outside angles of 45 and 90
degrees. To use the try square most effective­
ly, be sure to press the beam or stock of the
3­45
tool firmly against the edge of the board or
other material being checked or marked.
The sliding T­bevel (fig. 63) is similar to
the try square, but its blade is adjustable to
any angle. It is used for laying out angles
other than right angles, for testing bevels,
and for repeating or transferring angles from
one piece of lumber to another. To set the
sliding T­bevel, loosen the thumbscrew at the
rounded edge of the handle just enough to
permit the blade to slide along its slot and to
rotate with slight friction. Place the T­bevel
handle against one side of the required angle,
and the blade against the other side of the
angle. Tighten the thumbscrew so the blade
fits firmly against the handle.
30. PORTABLE ELECTRIC TOOLS
The portable electric tool outfit is designed
for a variety of uses including construction,
intrenching, timber cutting, bridging, and
clearing to reduce manual effort and increase
production.
The generator in the electric tool trailer is
a standard 3 KW, 60­cycle, 115­volt skid­
mounted unit.
All power tools should be grounded to pre­
clude electric shock. The cord generally has a
three­prong type plug. If the plug is the two­
prong type, it will be necessary to ground the
tool. This is done by connecting the post or
clip that extends from the third wire on the
cord to an electric conduit, a pipe, or a metal
rod driven into the ground. Safety goggles
should be worn when using power tools.
The portable electric drill can be used with
a wide variety of bits and attachments for
drilling holes, buffing, sawing, and driving
screws. It is essentially an electric motor in
a metal housing fitted with a chuck into which
a bit or other attachment can be fastened. It
has a spade handle or pistol­grip type handle.
Some drills have another attached "steady­
ing" handle and a bar that can be attached
for use as an auxiliary handle. To insert the
drill bit into the electric drill chuck, fit the
chuck key into the teeth of the chuck. Turn
the key counterclockwise until the chuck
opens enough to admit the shank of the bit.
Insert the bit and tighten the chuck jaws
securely by turning the key clockwise. Re­
move the key from the chuck and store the
key where it will not get lost.
The work to be drilled must be stationary
or firmly secured. Make a slight dent in the
spot to be drilled, by use of a center marker
or punch, so the drill bit will not bounce or
slide away from the place where the hole is
desired. Turn the drill switch on, hold the
drill in position, and place the revolving drill
bit on the marked spot. In drilling, exert
enough firm, even pressure to keep the bit
cutting, but do not use great pressure since
this can dull or break the bit. Keep the drill
at the required angle to the work, without
rocking the bit or changing its angle.
While drilling, withdraw the bit frequently
from the work to clear the chips from the bit
flutes and to allow the bit to cool so it will
not lose its tempering or break. If the bit
binds, this is an indication that its flutes are
jammed with shavings. Always keep the bit
turning with power on while withdrawing it
from the hole.
The portable electric hammer can be used
for beveling, caulking, beading, drilling in ma­
sonry, driving nails, digging in clay, breaking
light concrete, and performing other similar
jobs. The portable electric hammer consists
of a metal housing on a spade type or pistol­
grip handle. Inside the housing, a strong
spring moves a steel piston back and forth in
a pounding manner when the power switch is
on. The housing's nozzle is designed to hold
a variety of bits such as chisels, diggers and
tampers. The forward stroke of the piston
activates the bit. A removable tool­retaining
spring clip is located at the housing nozzle. In
using the electric hammer, the bit to be used
is slid into the nozzle so it snaps into place
and is held securely. The handle of the electric
hammer is held firmly with one hand while
the other hand steadies and guides the tool.
Operations performed with this hammer re­
quire the use of safety goggles to protect the
eyes.
3­46
The electric impact wrench is used primari­
ly for installing and removing nuts, bolts, and
screws. It can also be used with proper ac­
cessories to drill and tap a variety of ma­
terials, to drive studs, and to drive or remove
socket­head or self­tapping screws.
It consists of a pistol­grip handle on a
metal housing containing the motor that
activates the socket­retainer/driving­anvil
inside the muzzle of the housing. Attach­
ments used with this wrench are fastened to
the driving anvil by snapping them onto the
socket retainer. A ratchet switch makes it
possible to reverse the action of the tool for
loosening or tightening work.
Before using the electric wrench, check that
the wrench and its reversible features are
functioning correctly. Do this by connecting
its cord to a suitable power source, depressing
the on­off switch, and allowing the wrench to
operate a few seconds while noting the direc­
tion of the rotation. Stop the wrench, adjust
the ratchet switch so the direction is re­
versed, and start the wrench again.
Some of the most common uses of the
portable electric circular saw are cutting
studding to length, cutting off the ends of
subfloors or sheathing, ripping boards and
planks, and preparing inside and outside trim.
The pioneer electric tool set's saw has a 10­
inch blade. The blades are available with
teeth specifically designed for crosscutting or
ripping. There is also a blade with a combina­
tion of cutting and raker teeth, for ripping,
crosscutting, or mitering.
To use, set the saw's guide to the correct
angle and depth of cut. Be sure the material
to be sawed is steadied by its own weight or
is secured firmly by clamping or wedging.
Press the switch trigger in the handle to start
the saw. The saw blade must be revolving at
full speed before it contacts the material to
be cut. When cutting, apply firm pressure but
do not force the saw. To attach a new blade
make certain that the teeth are in the proper
cutting direction (pointing upward toward
front of saw) and tighten the flange and
clamp­screw with the wrench.
Electric disk sanders can be used for heavy­
duty sanding, grinding, wire brushing, and
planning. Before using the sander, secure the
proper attachment to the spindle, and be
sure the work is stationary or make it so by
weights or clamps. Switch on the sander so
the attachment is turning before placing it
on the work surface. Grasp the sander firmly
with one hand on each handle, and begin
sweeping the machine back and forth over
approximately an 18­inch span, using light
pressure.
Chain saws are used in cutting logs and
timber. They are used horizontally in felling
trees and vertically in cutting logs. The gaso­
line driven chain saw, a component of the
portable electric tool set, is a portable one­
man saw with the teeth arranged on a flexible
steel chain­like belt that rotates so the teeth
cut only in one direction, toward the power
end of the saw. It has a pistol­grip handle and
a sturdy bar frame above the engine for
holding and guiding. Before using the chain
saw, make sure the teeth on the chain have
been positioned correctly, so the saw cuts
toward the end of the saw where the motor
or engine is attached. Also be sure the teeth
are sharp and undamaged. In sawing, hold
the chain saw against the tree, pile, or timber
to be cut, and apply light pressure in guiding
the saw through the work. When cutting
felled logs, the weight of the saw furnishes
enough pressure and the saw user simply
guides the saw.
In the care of portable power tools, keep
them, and especially their housing intake and
exhaust holes, clean and free of dust and dirt
at all time. Wipe these tools with a soft
cloth and use compressed air to blow sawdust
and other particles from areas that cannot be
reached with a cloth. Examine the tool's cord
for exposed or loose wires and for damaged
insulation. Wipe the cord clean often to pre­
vent deterioration from oil or grease. Check
the cord's ground wire connection to make
sure it is not loose, and check the plug for
loose prongs or cracked casing. Do not hold
or drag the electric tool by its cord at any
time. Store power tools in containers desig­
nated for this purpose or in the tool trailer,
3­47
after coating any rustable metal with oil.
An experienced technician should make a
periodic check of all electric tools to include
an examination of motor parts, cleaning,
brushes, wiring and commutator.
31. STORAGE
Emphasis should be placed on easy access
to those tools used most frequently.
Handtools issued in a special box, case, or
other receptable should be placed in that re­
ceptable when stored. A list of tools that
belong in each toolbox should be part of the
toolbox, for inventory purposes and to aid in
replacing each tool where it belongs.
32. TOOL MAINTENANCE INSURES MAXIMUM
LIFE TO TOOLS
To prevent rust on metal parts of hand­
tools, wipe those parts with a soft cloth that
has light oil on it. It is not necessary to coat
aluminum, galvanized metal, or other non­
rusting materials with oil.
Rub linseed oil into the wooden parts of
handtools when they feel slightly dry on the
surface, to preserve the wood and keep it from
drying out completely.
Painting handtools is another means of pre­
venting rust. Before painting a handtool, it
should be examined for cracks or breaks. The
cutting edges and serrated jaws or sections
should not be painted. Do not allow several
layers of paint to accumulate on, or paint to
run into, scored or knurled places on a tool,
where the scored places serve as a handhold.
Be careful to keep paint away from the tool's
swivels, slides, pivots, and other moving parts.
All edged tools should be kept sharp and
in top condition. There are three methods of
keeping tools sharp.
Whetting or honing­­When an edged
tool begins to show a slight dullness,
whet its cutting edge with an oilstone
or a combination carborundum stone.
These whetting or honing stones come in
a variety of shapes and sizes to fit all
types of tools.
Filing­­When an oilstone cannot be
used satisfactorily to whet a cutting
edge, a touchup with the proper size and
shape of file will help keep a keen cutting
edge.
Grinding­­When a tool's keen cutting
edge cannot be restored by whetting or
filing, an abrasive stone in the form of a
grinding wheel either hand operated or
power driven is used. The main point to
remember in grinding handtools, is to
avoid overheating the tool by prolonged
grinding. When grinding handtools, al­
ways wear goggles or some other ap­
proved shield to avoid injury from flying
particles. Keep control of the tool being
ground by steadying the hand against the
grinder's tool rest.
33. SAFETY
Constant attention to safety measures at
all levels within the unit is necessary to mini­
mize injury to personnel and damage to prop­
erty.
Before using any handtool, inspect it for
defects.
Store handtools in suitable storage space,
so that the tools do not injure persons who
are storing, removing, or working with them
in the toolroom.
Be sure handtools are not dirty, oily, or
greasy.
Do not carry sharp­edged or pointed tools
in pockets or where they could protrude and
cause injury.
Do not use metal or power tools in loca­
tions where source of ignition may cause a
fire or explosion.
Wear safety goggles or other approved
safety type face and eye protectors when per­
forming operations that might result in flying
particles.
Do not toss tools from one location to an­
other. When handtools must be passed be­
tween personnel and handing them over is
3­48
impossible or impractical, use suitable con­ tainers or rope.
Do not work on electrical circuits while cir­
cuit is on.
Do not wear loose or torn clothing that
may cause injury by becoming entangled with hand or power tools.
Do not swing a chopping or chipping tool until certain that no one in the vicinity will
be endangered by the back swing.
Use each handtool for the purpose for
which it was intended.
Never leave power tools running unat­ tended.
EXERCISES
First requirement. Solve multiple­choice
exercises 1 through 8 to show that you under­
stand the characteristics of rope and cable as
they apply to practical situations.
1. A coil of approximately 200
feet of 1­inch diameter manila rope has
been made available to your squad.
What is the maximum safe load weight
in pounds that is within the capacity of
the rope?
a. 2,250 c. 2,350
b. 2,300 d. 2,400
2. Your squad has received a coil
of new 3/4" rope with a protective bur­
lap covering. After removing the bur­
lap, where on the coil would you look
for the end of the rope to uncoil it?
a. top c. bottom
b. side d. outside
3. Your squad leader wants to
verify his proposed use of 1­inch diam­
eter mild plow steel (mps) wire rope,
for use as a sling. What is the safe
working capacity (swc) or safe work­
ing load of this cable? (Round off to
nearest thousand pounds.)
a. 8,000 c. 32,000
b. 16,000 d. 64,000
4. A wire rope which is being used
in hoisting operations is noticeably
kinked. What action should you take?
a. reeve the hoist with a new cable
b. run the hoist without a load to work
the kink out
c. smooth out or cut off the frayed
ends
d. cut out the kinked portion before
use
5. The size of wire in wire rope
gives the rope various qualities. If a
rope has a small number of large wires
making up the strands, what properties
would the rope have?
a. very flexible and very resistant to
external abrasion
b. not very flexible but very resistant
to external abrasion
c. not very flexible and not very re­
sistant to external abrasion
d. very flexible but not very resistant
to external abrasion
6. Your squad has been given a
mission to cut and seize a 200­foot 7/8­
inch diameter wire rope into 100­foot
sections. How many seizings would be
necessary for each side of the cut?
a. 3 c. 4 b. 3 d. 5
7. In addition to selecting the
correct number of seizings, spacing of
the seizings is also important. About
3­49
how far apart in inches should the seiz­
ings in exercise 6 be?
a. 1 c. 3
b. 2 d. 6
8. The proper length of the indi­
vidual seizing is also important. In ex­
ercise 6, we determined the proper num­
ber. In exercise 7 we determined the
spacing between seizings. What is the
length of the individual seizings for ex­
ercise 6?
a. 1/2 to 1 inch
b. 1 to 2 inches
c. 1 1/2 to 2 1/2 inches
d. 3 to 4 inches
Second requirement. Multiple­choice exer­
cises 9 through 19 will provide an opportunity
for you to test your knowledge of knots,
splices, attachment, anchorages, and slings.
9. What knot would you use to
prevent the end of a rope from slipping
through a fastening or loop in another
rope?
a. butterfly knot
b. carrick bend
c. square knot
d. figure eight knot
10. Each knot, bend, or hitch serves
a particular function or is best suited
for a particular purpose. Which knot
is used for heavy loads and for joining
large hawsers or heavy rope?
a. square knot
b. figure eight knot
c. butterfly knot
d. carrick bend
11. You have been given the task
of joining two ropes of unequal size.
What knot would give you the greatest
holding power?
a. square knot
b. single sheet bend
c. double sheet bend
d. overhand knot
12. There are a variety of knots
that are suited for various jobs. What
knot is used to make a boatswains
chair?
a. single sheet bend
b. double bowline
c. catspaw
d. two half hitches
13. Some knots are especially suited
for use in rescue work. What knot
would you use to lift an unconscious
man?
a. catspaw
b. French bowline
c. Spanish bowline
d. bowline on a bight
14. You are preparing to splice two
fiber ropes. How many turns must you
unlay on the end of each rope to form
a short splice?
a. 7 c. 9
b. 8 d. 10
15. There are three types of end
fittings which may be placed directly
on wire rope and are easily changed.
What are these three types?
a. open socket, wedge socket, and
closed socket
b. wedge socket, open socket, and clips
c. clips, clamps, and open socket
d. wedge socket, clips, and clamps
3­50
16. You have been issued a roll of
1/2­inch fiber rope to be used for slings
in hoisting and removing operations.
What is the safe vertical lift capacity
in pounds of these slings when used
singly?
a. 275 c. 418
b. 390 d. 475
17. What is the safe working ca­
pacity in pounds of a single wire rope sling of improved plow steel with a 1/2­inch diameter?
a. 1,690 c. 4,320
b. 3,560 d. 5,460
18. When using slings, care must
be exercised not to exceed their lift
capacity. What is the vertical lift ca­
pacity in pounds of a single sling made
from 3/4­inch new improved plow steel
(ips) wire rope?
a. 4,320 c. 16,800
b. 9,480 d. 21,000
19. In all three types of anchorages,
the pull exerted on the anchorage by
the guyline should be at what angle to
minimize the possibility of pulling the
anchorage out of the ground?
a. as perpendicular to the ground as
possible
b. at 45ø angle to the ground
c. as nearly parallel to the ground as
possible
d. at 30ø angle from the vertical
Third requirement. Multiple­choice exer­
cises 20 through 28 provide an opportunity
for you to show that you understand guylines
and various devices used to lift and move
loads.
20. You are a member of a crew
erecting a gin pole. Lashings for at­
taching the tackle are usually made
before guidelines are attached. How many
inches below the top of the gin pole
should the lashing be attached?
a. 12 c. 18
b. 15 d. 24
21. In making the guylines for a
gin pole, you use one rope to form two
guylines. How many times longer than
the gin pole should you cut this rope?
a. 2 c. 4
b. 3 d. 5
22. How many feet up from the
bottom of the gin pole should you at­
tach the snatch block?
a. 2 c. 6
b. 4 d. 8
23. How many feet deep should you
dig the hole in the ground for the base
of a 40­foot gin pole?
a. 1 c. 3
b. 2 d. 4
24. You have been assigned the
task of constructing a tripod in which
the middle pole is pointed in the op­
posite direction from the other two
while the spars are being lashed to­
gether. How much space do you leave
between spars at the place that they
are lashed together?
a. diameter of spars
b. half the diameter of the spars
c. twice the diameter of rope used
d. width of diameter of rope used
25. The legs of a tripod in its final
position should be spread so that each
leg is equidistant from the others. How
far should this spread be?
a. not less than one­half and not more
than two­thirds the length of the
legs
3­51
b. not less than two­thirds and not
more than the length of the legs
c. one­fourth the length of the legs
d. not less than one­fourth and not
more than three­fourths the length
of the legs
26. You have two 12­inch diameter
poles 25 feet long with which to con­
struct a set of shears. How many inches
of space should you have between the
poles at the place you lash them to­
gether?
a. 1 c. 4
b. 2 d. 6 27. If the height of the shears is
20 feet, what distance in feet should the
spread of the legs be?
a. 4 c. 8
b. 6 d. 10
28. You are constructing a boom
derrick to lift loads where a long hori­
zontal reach is necessary. The mast of
the boom derrick is constructed in the
same manner as a gin pole. The length
of the boom should not exceed what
fraction of the length of the mast?
Fourth requirement. Multiple­choice exer­
cises 29 through 32 will require you to apply
your knowledge of pioneer tools issued to the
engineer platoon.
29. An adz, when used properly,
can be a valuable tool, but it can be
dangerous if used improperly. How
would you position yourself while
smoothing a log with this tool? (As­
sume the log has been blocked so it will
not slip.)
a. straddle the log
b. hold the log with either the right
or left foot
c. kneel on one knee to be closer to
the work
d. hold the work in one hand while
chopping with the other
30. In widening a road, a crew has
felled several large trees. Pending re­
pair of the chain saw, what type of saw
would be used to cut them up?
a. crosscut handsaw
b. rip saw
c. hack saw
d. two­man crosscut
31. If you had to remove a coupling
from a piece of pipe, what type of
wrench would be appropriate?
a. open­end nonadjustable
b. crescent
c. monkey
d. stillson
32. A building, weighing approxi­
mately 10 tons, must be raised in order
to level it by placing shims on top of
the footings. Which of the following
tools would you use for this purpose?
a. pinch bar c. jack
b. wrecking bar d. crowbar
Fifth requirement. Solve multiple choice
exercises 33 through 37 to test your under­
standing of the purpose and use of selected
carpenter tools found in the engineer platoon.
33. You notice that one of your
fellow soldiers who is trying to saw a
board parallel to the grain is having
difficulty. What type saw should be
used under these conditions?
a. ripsaw
b. large crosscut saw
c. crosscut handsaw
d. hacksaw
3­52
34. Which of the following tasks would you normally perform using a chalkline?
a. checking the squareness of con­
struction timber
b. measuring the distance between
batterboards
c. marking a road centerline
d. staking out foundations
35. In framing a building the studs
or vertical members are placed either
16 or 24 inches apart. What tool is
particularly adapted to establishing
center­to­center spacing between studs?
a. carpenter's level
b. combination square
c. carpenter's square
d. carpenter's rule
36. You have been given the task
to determine if a taut string line be­
tween two batter boards is horizontal.
What tool would you normally use to
check this?
a. line level
b. plumb bob
c. combination square
d. sliding T­bevel
37. What is the principal difference
between a combination square and a
T­bevel?
a. the combination square has a bubble
for leveling purposes
b. the combination square is not ad­
justable
c. the sliding T­bevel is not adjustable
d. the sliding T­bevel is graduated in
inches
Sixth requirement. Solve multiple­choice
exercises 38 through 43 as a means of dem­
onstrating your knowledge of the portable
electric tool outfit issued to the engineer pla­ toon.
38. What precautions should you
take when using an electric power drill?
a. ground to preclude electric shock
b. run the drill before inserting the
bit
c. avoid pressure on the drill
d. run the tool slowly to avoid over­
heating
39. If you have to drill several
small holes in concrete or masonry,
which tool from the portable electric
tool outfit would you use?
a. electric drill
b. impact wrench
c. electric hammer
d. electric spud
40. What before­operations check
should you make when preparing to
use the electric impact wrench?
a. sharpness of drill components
b. oil level in tank
c. pressure required for operation
d. reversible features
41. The portable circular saw is a
widely used tool. It is important that
the saw blade be installed properly for
safe operation. Some blades are stamped
"this side out". If the blade is not
stamped, how should you install it?
a. with the teeth pointing upward at
the front of the saw
b. with the teeth pointing downward
at the front of the saw
c. with the teeth on the bottom point­
ing backwards
d. with the manufacturer's name on
the outside
3­53
42. Power to operate electric power
tools is provided by the generator.
Which major component of the portable
electric tool outfit is independently gaso­
line­powered?
a. drill c. chain saw
b. sander d. hammer
43. What power tools can be found
in the portable electric tool outfit?
a. impact wrench, drill, circular saw,
and paving breaker
b. electric hammer, machinist's lathe,
gasoline saw and sander
c. electric drill, impact wrench, elec­
tric hammer and circular saw
d. circular saw, sander, electric ham­
mer, and pneumatic rock drill
Seventh requirement. Solve multiple­choice
exercises 44 through 48 to test your under­
standing of care, maintenance, and safety
procedures involving handtools.
44. Experience has shown that tool storage is an extension of good house­ keeping practice. In arrangement of
storage space for engineer tools, what
would you emphasize particularly?
a. avoidance of damage to tools
b. easy access to tools used frequent­
ly
c. avoidance of moisture
d. security
45. Unless tools are kept properly
sharpened their effectiveness will be
seriously reduced. How should edged
tools that receive normal use and no
abuse, be sharpened?
a. buffing c. grinding
b. filing d. whetting
46. If you find it necessary to
sharpen an ax on a power­driven
grinder in order to remove deep nicks,
what precaution should you observe to
avoid further damage to the tool?
a. avoid prolonged grinding
b. have grinder turn away from tool
c. run the grinder at half speed
d. use oil on the grinding wheel
47. Efficient use of handtools in­
cludes safe handling of tools to avoid
injury to the operators, helpers, and
others in the work area. What protec­
tive device should be used when grind­
ing, striking metal with metal, drilling,
chipping, etc?
a. gloves c. goggles
b. hardhat d. safety shoes
48. If you were using a carpenter's
level on a roof 12 feet from the ground
and it was needed by someone else work­
ing on the ground, what is the safest
way you would get it down?
a. drop it carefully over soft ground
so it could be caught
b. slide it down on a board
c. let it down on a handline
d. carry it down personally
LESSON 4
ENGINEER EQUIPMENT
CREDIT HOURS _______________________2
TEXT ASSIGNMENT ____________________Attached memorandum.
MATERIALS REQUIRED _________________None.
LESSON OBJECTIVE ___________________To increase your knowledge of engineer con­
struction equipment and tools, and con­
crete operations. ______________________________________________________________________________
ATTACHED MEMORANDUM
Section 1. EARTHMOVING EQUIPMENT
1. TRUCK, DUMP
The truck, dump (dump truck) is designed
for use over all types of roads, highways, and
cross­country terrain, and in all types of
weather. It will ford a hard­bottom stream
to a depth of 30 inches. It is used to haul
and dump earth, sand, gravel, coal, and the
like. It can also be used as a transport for
general cargo.
The dump truck is equipped with­­
a five­speed transmission
a two­speed transfer case
air­actuated, hydraulic type service
brakes
a pintle hook at the rear to permit tow­
ing of a trailer.
To protect the operator, the cab is en­
closed with a removable canvas tarpaulin.
The dump body includes a cab protector,
combination side racks, and troop seats. It
has a capacity of 5 cubic yards and a uni­
versal type tailgate which may be opened at
either the top or the bottom.
2. TRACTOR, FULL TRACKED
Tractors, full tracked (crawler tractors)
serve many purposes, such as prime movers
for pulling or pushing loads, power units for
winches and hoists, and moving mounts for
dozer blades, side booms, and scoop loaders.
The three major assemblies are a center
section and two side sections.
The center section contains the power
source and the operator's controls.
The side sections consist of track frames
which mount tracks extending approxi­
mately the full length of the tractor.
Crawler tractors are classified according
to weight and minimum and maximum draw­
bar pounds pull. This means light, medium,
and heavy class tractors; for example, a D6S
is in the light class, D7E and HD16M are in
the medium class, and D8 and TD24 are in
the heavy class. These tractors are equipped
with diesel engines with rating from 85 to
202 brake horsepower, and either 4 or 6
cylinders depending on make and model. They
attain much of their all­type­terrain versa­
tility from their low ground bearing pressure
at the track, which varies from about 6 to 9
pounds per square inch, depending on the
particular model.
Dozer blades consist of a moldboard, cut­
ting edges, side bits, and blade arms con­
necting the blade to the tractor. The cutting
edges and side bits are replaceable and made
of hardened steel.
4­1
Blade design allows either edge to be
raised or lowered from the horizontal posi­
tion. The top of the blade can be pitched
forward or backward, and the blade can be
angled from the direction of travel. Gen­
erally, at least two of these features are in­
corporated in a single blade type.
Blades vary in size and are designed to
perform different earthmoving functions.
The straight blade is mounted in a fixed
position perpendicular to the line of
travel of the tractor. It can be tilted
laterally approximately 12 inches, and
the blade top can be pitched either for­
ward or backward within a 10ø arc.
The angle blade is designed so the blade
can be set at angles up to approximately
25ø to the direction of travel of the
tractor. It also can be set at right angles
to the tractor and used as a straight
blade. When angled, the blade can be
tilted up to approximately 12 inches but
cannot be pitched.
Blades having a tilting characteristic are
used for cutting ditches and breaking through
crusted material. The tilting ability permits
the concentration of the tractor power upon
a small segment of the blade. The pitching
characteristic will permit a variance in ground
pressure of the blade; thus, penetration will
be increased or decreased accordingly. Chang­
ing the blade pitch will provide a cutting or
dragging action, whichever is desirable.
Angle blades are most effective when used
to sidecast materials during a backfilling
operation or in making a sidehill cut. In
addition, they have been successfully used for
rough grading operations and for spreading
piles or windrows of material.
Back rippers mounted on drawbar tractors
provide a means of breaking up hard surfaces
(pavements and so on) not easily penetrated
by dozer blades. They generally consist of
four curved shanks with lock­on teeth which
can penetrate depths up to 9 inches.
3. GRADER
The grader can be employed for leveling
and crowning, mixing and spreading, ditch­
ing and bank sloping, and sidecasting ma­
terial. It may also be used for maintaining
haul roads and for light stripping operations,
but it is not intended for heavy excavation.
When ditches deeper than 3 feet are to be
constructed, it is more economical to utilize
some other type of equipment.
The grader consists of a scarifier, mold­
board or blade, and circle mounted on draw­
bars which are pivotally connected to the
front of the main frame.
Controls for starting and operating the ve­
hicle are located in the operator's compart­
ment.
Section II. LIFTING AND LOADING EQUIPMENT
4. CRANE­SHOVEL, TRUCK MOUNTED
The basic crane­shovel unit consists of a carrier, truck mounting, and
revolving superstruc­
ture or upper revolving frame. This unit is supplied with a crane boom for
lifting, and de­
signed for use with shovel, clamshell, dragline, backhoe, or piledriver
attachments.
The superstructure upon which are mounted the engine, upper machinery, and
gantry re­
volves on a bearing mono­race.
Except for two outriggers on each side to improve stability, the carrier is
equipped like
the dump truck.
4­2
Note: The following warning is placed on the inside of the crane­shovel and
must be ob­
served at all times.
__________________________________ WARNING____________________________________
OPERATIONS ADJACENT TO OVERHEAD LINES IS PROHIBITED UNLESS ONE OF
THE FOLLOWING CONDITIONS IS SATISFIED
POWER HAS BEEN SHUT OFF AND POSITIVE MEANS TAKEN TO PREVENT
1 LINES FROM BEING ENERGIZED.
REQUIRED
POSITION AND BLOCK EQUIP­ VOLTAGE CLEARANCE
MENT INSURING NO PARTS, UNDER 69 KV _______________ 10 FEET
2 INCLUDING CABLE, CAN COME 69 KV ___________________ 12 FEET
WITHIN THE FOLLOWING 115­161 KV ________________ 15 FEET
CLEARANCES: 230­285 KV ________________ 20 FEET
345 KV ___________________ 25 FEET
500 KV ___________________ 35 FEET
IF EQUIPMENT MUST BE OPERATED CLOSER THAN CLEARANCE SPEC­
IFIED IN 2 ABOVE, AN INSULATING CAGE AND AN INSULATING LINK
3 SHALL BE PROVIDED TO PROTECT AGAINST LINE VOLTAGE AT WORK
AREA.
5. CRANE BOOM
The crane boom is usually made in two
sections fastened approximately in the center
by one of two methods: bolted butt plate
(flange) connection or pin and clevis con­
nection.
The upper section with the boom head
and a system of sheaves is usually but
not necessarily the same length as the
lower section.
The crane boom is also the basis for the
clamshell, dragline, and piledriving op­
erations.
Basic crane equipment includes hoist
drums, hook block to provide the required
parts of line (reeving), and the boom suspen­
sion and hoist wire ropes.
Cranes are units used primarily for lift­
ing an object or load, transferring it to
a new location by swinging or traveling,
and then placing the load in the new
location.
The types of loads that can be handled
are determined by the types of acces­
sories that are available for use on the
hook. These accessories include, but are
not limited to, slings, concrete buckets,
and magnets.
6. SHOVEL
The shovel attachment includes the shovel
boom; dipper stick; bucket; mechanism for
crowding, retracting, and dumping the buck­
et; and necessary wire ropes. The shovel is
designed to operate against a face or bank
which it displaces as it moves forward.
7. CLAMSHELL
The clamshell equipment consists of a
crane boom, hoist drum laggings, clamshell
bucket, tagline, and the necessary wire ropes
­­boom, holding, closing, and tagline. Like
the crane, the clamshell is a vertically op­
erated attachment capable of working at,
above, and below ground level, but equipped
with a bucket instead of a hook block.
The clamshell is capable of digging loose
to medium type soils in all zones as well
as dumping in any of the three zones.
The height that can be reached by the
clamshell is dependent on the length of
boom used.
4­3
The depth reached by the clamshell is
limited by the length of wire rope that
the cable drums will accommodate.
8. DRAGLINE
The dragline components consist of the lat­
tice type boom, dragline bucket, and fairlead
assembly.
It can be employed on dredging opera­
tions where the material handled is wet
and sticky.
It can dig trenches, strip overburden,
clean and dig roadside ditches, and slope
embankments.
When handling mud the dragline is the
most practical attachment to use as its
reach enables it to handle a wide area
from one position, and the sliding action
of the bucket offsets the suction effects.
9. BACKHOE
The backhoe attachment consists of five
major components: dipper, dipper handle,
box type boom, auxiliary A­frame, and a
grooved drum lagging that is installed on
the front drum for the dipper pull rope. It
is most suited for trench excavating as it
is capable of digging well below the tracks
of the unit, and capable also of digging soft
to hard material because the weight of the
boom plus the positive pull on the dipper is
used to force the dipper into the material.
10. PILEDRIVER
The piledriver attachment consists of a
crane boom, adapter plates, leads, catwalk,
hammer, pile cap, and the necessary wire
ropes. It is used to drive various types of
wood and concrete piles, and sheet­steel piling
for foundations, sheathing, cofferdam work,
and the like.
11. SCOOP LOADER The scoop loader like the crane­shovel is a
lifting and loading item. It can be utilized in
all zones of operation and can dig at ground
level, above ground level, and below ground
level. The loader can travel from one con­
struction site to another under its own power.
Typical uses of the scoop loaders are stock­
piling materials, digging gun emplacements,
backfilling ditches, loading trucks, lifting and
moving construction materials, and when
equipped with rock type tread tires they can
operate efficiently in and around rock quar­
ries.
Section III. AIR COMPRESSORS
12. AIR COMPRESSORS An air compressor is a machine for com­
pressing air from an initial intake pressure
to a higher exhaust pressure through reduc­
tion in volume.
It consists of a driving unit, a compressor
unit, and their accessories.
The driving unit provides power to op­
erate the compressor and may be a gaso­
line or diesel engine.
The compressor is governed by a pres­
sure control system which is adjusted
to compress air to a minimum pressure
of 100 pounds per square inch (psi). The
compressor may be of reciprocating or
rotary design.
Air compressors should always be as
level as possible and never tilted more
than 15ø from a level plane.
The accessories include such items as an
aftercooler, intercooler, air receiver tank,
and a pressure control system.
13. AFTERCOOLER
The presence of water or moisture in an
air transmission line is not desirable. The
4­4
most satisfactory means of minimizing these
conditions is to remove the moisture from
the air immediately after compression and
before the air enters the distribution systems.
This can be accomplished very efficiently
through the use of an aftercooler, which is
an air radiator that transfers heat from com­
pressed air to the atmosphere.
The aftercooler reduces the temperature
of compressed air to the condensation
point where most of the moisture is re­
moved.
Cooling the air eliminates the difficulties
which moisture causes, not only at points
where air is used, but also throughout
the distribution system.
14. INTERCOOLER
If air is compressed to 100­pound gage
pressure without heat loss, the final tempera­
ture would be about 485øF. This increase in
temperature raises the pressure of the air
under compression, thus necessitating an in­
crease in work to compress the air.
After the air is discharged into the re­
ceiver tank and lines, the temperature
rapidly falls to near that of the sur­
rounding atmosphere, thus losing part of
the energy generated during compres­
sion.
The ideal compressor would compress the
air at a constant temperature but this
is impossible in present­day compressors.
In some compressors the work of compres­
sing is divided between two or more stages,
depending upon the final discharge pressure
required. An intercooler is employed between
the different stages to reduce the temperature
of the compressed air between stages.
The amount of cooling surface required
is dependent upon the quantity of free
air compressed per minute and the final
discharge pressure.
Theoretically, the cooler should have a
sufficient amount of cooling surface to
reduce the temperature between stages
to that of the low pressure cylinder in­
take.
15. AIR RECEIVER TANK
The receiver tank is of welded steel con­
struction and acts as a surge tank and con­
densation trap. It stores enough air during
operation to actuate the pressure control
system and is usually fitted with at least one
service valve, one drain valve, and a safety
valve.
16. PRESSURE CONTROL SYSTEM
Every compressor is governed by a pres­
sure control unit. In a reciprocating com­
pressor, when the pressure reaches a set
maximum, the pressure control unit causes
the engine to idle and the suction valves of
the compressor to remain open; on a rotary
compressor the valve in the intake manifold
is closed and the engine idles. Therefore, in
both, no air is compressed. When the pres­
sure drops below the set minimum, the pres­
sure control unit causes the engine to increase
speed and the suction valves to close; there­
fore, air will be compressed.
Section IV. PNEUMATIC TOOLS
17. GENERAL
To operate pneumatic tools, two require­
ments are demanded from the air compressor,
a specific volume of air (expressed in cubic
feet per minute (cfm) and a specific pressure
(psi). The number of tools that may be op­
erated from an air compressor depends on
the total air requirement of the tools.
Example: A certain tool requires 95 cfm at
80 psi.
4­5
A 210 cfm compressor could supply air
to operate two such tools. This would
require 190 cfm.
If another tool were added, this would
overload the compressor and cause ex­
cessive wear.
When the pressure and volume to a
pneumatic tool are reduced 10 percent
below the set minimum, the efficiency
of the tool is reduced 41 percent.
The advantages of pneumatic tools are as
follows:
Ease of maintenance­­a pneumatic tool
has the advantage of simplicity of de­
sign over similar gasoline or electric
powered tools, and requires less main­
tenance.
There are few wearing parts in pneu­
matic tools whereas gasoline tools have
many.
An electric tool has only a few parts,
but few operators possess the technical
ability or the equipment to repair them
in the field.
Ease of operation­­pneumatic tools are
simpler to operate than gasoline or elec­
tric powered tools.
Little specialized training is required,
and even an unskilled soldier can be
taught the basic principles of operation
in a short time.
Durability­­pneumatic tools are much
more rugged than gasoline or electric
powered tools.
Minimal special care is required while
being transported or in storage.
Climatic conditions­­pneumatic tools
are not affected by wet weather opera­
tions. In fact they can be operated under
water without any ill effects.
However, extreme cold or high humidity
can present problems. As the air is ex­
hausted from the exhaust port the ex­
pansion results in supercooling, causing
ice to form around the exhaust port
which eventually will stop the tool's op­
erations. This can be corrected by using
nonpermanent antifreeze or alcohol solu­
tion in the air line oiler to prevent the
moisture from freezing.
Safety­­pneumatic tools with nonspark­
ing attachments can be operated around
petroleum and explosive material with­
out presenting a fire hazard.
Overloading­­pneumatic tools will not
be damaged in case too great a load is
placed on the working device, providing
it is used properly.
The disadvantages of pneumatic tools are
as follows:
The radius of operation for a pneumatic
tool is limited by the length and size
of air hose to which it must be attached.
If the tool is moved too far from the
source of power (200 feet maximum with
3/4­inch diameter hose), friction line loss
will hinder the operation of tools.
Failure of power source­­if the com­
pressor fails, all tools being operated
from the compressor become useless.
Cumbersomeness­­a pneumatic tool is
frequently difficult to handle because of
its attachment to the air hose. This is
particularly true in rough terrain where
the hose has a tendency to hang on rocks
or brush.
18. CHAIN SAW
The chain saw is a heavy duty saw intended
primarily for cutting trees and large timbers
up to 24 inches in diameter. It weighs 45
pounds and has an air requirement of 90 cfm
and a recommended air pressure of 80­100
psi.
The saw is a portable two­man saw with
the teeth arranged on a flexible steel chain­
like belt that rotates so the teeth cut only
in one direction, toward the power end of the
saw.
During operation, hold the chain saw
against the object to be cut and apply light
pressure on both ends, guiding the saw
through the work.
4­6
Failure to maintain proper blade tension
causes the biggest maintenance problem on
the chain saw.
The blade should be adjusted to maintain
1/2­inch slack when pulled up at the cen­
ter. More slack than this will allow it
to jump out of the saw guide, causing
the blade to bend or break.
If the blade is too tight, it will bend and
cause sprocket damage.
Safety precautions include­­
Wear safety goggles.
Maintain the proper blade tension.
Maintain a firm grip and good footing at
all times.
Never force the saw into the wood; allow
it to cut at its own speed.
Be sure the bumper spikes are held se­
curely against the work before starting
the saw.
Be careful that the saw is not twisted or
bound in the cut.
Always keep the work position clear of
material that has been cut.
19. CIRCULAR SAW
The circular saw is used for crosscutting
or ripsawing timber for construction pur­
poses. The saw weighs 25 to 32 1/2 pounds
according to make and model, has an air
requirement from 55 to 75 cfm, and a recom­
mended air pressure of 80­100 psi.
The circular saw at 45 degrees can cut to
a depth of 3­5/16 inches. At 90 degrees it
can cut to a depth of 4 3/8 inches.
To operate, set the saw to the correct angle
and depth of cut. Two V notches on the front
of the foot simplify cutting to a line.
Be sure the material to be sawed is stead­
ied by its own weight or is secured firmly
by clamping or wedging.
Depress the switch trigger in the handle
to start the saw.
The saw blade must be revolving at full
speed before it contacts the material's
cutting surface.
When cutting, apply firm pressure but
do not force the saw.
In many cases, the pneumatic circular saw
is inverted and used as a table saw. When this
is done, the exhaust port is exposed to the
wood cuttings. An accumulation of these
cuttings will clog up the air motor and make
the saw useless.
For best performance­­
The two grease fittings that lubricate the
rotor shaft bearing and governor should
be lubricated weekly according to lubri­
cation orders.
The gearcase should be checked every 8
hours to insure that lubricant just covers
the worm gear.
To operate the saw safely­­
Never tighten, loosen, or change the
blade while the saw is connected to the
air line.
Never operate the saw with a defective
telescopic guard or with the guard held
in an open position.
Check all wood for nails and metal before
making a cut.
Never pull the blade backwards or with­
draw it from the cut while the blade is
rotating.
Adjust foot to minimum depth required
for cut.
Keep hand away from moving blade, and
shut off air when the tool is not in use.
20. NAIL DRIVER
The pneumatic nail driver and rivet buster
is a long­stroke piston type riveting hammer
with nail­driving attachments for holding 1/2­
inch and 3/4­inch diameter nailheads. It is
used primarily for driving large nails, spikes,
and driftpins into heavy or large timbers, or
for cutting the heads off rivets. The hammer
weighs 25 pounds, has an air requirement for
4­7
32 cfm, and a recommended air pressure of
90 psi.
Before operation insure that an air line
oiler is in place to lubricate the nailer.
Start all nails or spikes with a hand ham­
mer.
Aline nail set to angle of nail or spike
and always keep the attachment in con­
tact with the object being driven.
Attempts to countersink a nail with the
nail driver will result in a broken re­
tainer spring.
As part of the nail driver maintenance,
lubrication of the driver is done through an
air line oiler (par 27). Retainer housings on
nail drivers often break because operators
fail to keep the nail set against the work.
As safety measures­­
Keep air connections tight.
Keep exhaust away from the body.
Never make adjustments or attempt to
change attachments without bleeding the
tool and disconnecting the hose.
21. WOOD BORER
The pneumatic reversible wood borer drill
is a heavy duty low speed machine designed
to drive ship auger type drills. It is used
extensively in trestle bridge and other timber
construction work where it is necessary to
drill holes for bolts or pins. The drill weighs
30 pounds, has an air requirement of 60 cfm,
and a recommended air pressure of 80­100
psi. Drill bits are issued in 12­ and 36­inch
lengths and in diameter sizes of 7/16­inch,
3/4­inch, and 2­inch.
To operate, always start the drill slowly
until the screw is well set.
When using the small diameter bits, al­
ways start the hole with the 12­inch
length and then use the 36­inch length.
Hold the drill firmly but do not force it.
Exert enough effort to counteract the
tendency of the tool to rotate, and be
prepared to resist the torque in case the
bit becomes stuck.
During boring and withdrawing of the
auger, keep it in line with the hole.
As preventive maintenance, check the oil
reservoir after every 4 hours of operation.
When required, refill with OE 10 below 32
degrees, and OE 30 above 32 degrees.
Lubricate the grease fittings after 64 hours
of operation.
As a safety precaution­­
Hold the tool firmly but do not apply too
much pressure as this could cause the
bit to overheat and possibly break.
Disconnect tool before making adjust­
ments.
22. BACKFILL TAMPER
The backfill tamper is a percussion or piston
type manually controlled tool. It is used to
compact loose earth in small or confined areas
that are not accessible to other types of
compaction equipment. The tamper weighs
34 pounds, has an air requirement of 24­27
cfm, and a recommended pressure of 80­90
psi. To operate, allow the tamper to work at
its own speed, but keep it moving across the
fill and do not let it rest in one position.
When tamping loose earth, better results
can often be obtained by wrapping the
tamping head with burlap or similar ma­
terial. However, when tamping gravel,
leave the head unwrapped.
Tamp in 2­ or 3­inch lifts in small areas,
moving the tamper continuously.
As a part of the maintenance requirement,
lubricate with OE 10 all year.
Overlubrication causes failure of the
packing gland and seal.
For the non­self­lubricating tamper,
there is a lubricating button. To lubricate
this model, depress the button for 10
seconds while tool is on after every 2
hours of operation.
4­8
Do not operate the tamper so that the
tamper butt hits the material at an angle;
this causes the piston to break where
it attaches to the tamping butt.
For safe operation­­
Keep tool away from feet and head.
Wear goggles when compacting hard ma­
terials, gravel, and the like.
23. PAVING BREAKER, 80­LB
The paving breaker, 80­lb is a heavy duty
reciprocating­percussion type tool. It is used
for heavy duty demolition work on concrete,
brick, asphalt, macadam, and the like. It is
also used for the demolition of walls, columns,
piers, and foundations, and for general rock
breaking. The breaker weighs 75­90 pounds,
has an air requirement of 60­65 cfm, and a
recommended air pressure of 80­90 psi.
The four attachments issued with this pav­
ing breaker are: moil point, chisel point,
tamper, and sheeting driver.
The moil point is a 20­inch long piece of
1 1/4­inch hexagonal tool steel, pointed at one
end and having a retainer collar 6 inches
from the opposite end. It should be used
when breaking through concrete, stone, or
material of a similar high abrasive and densi­
ty character.
The chisel point is similar to the moil point
except that it has a 3­inch wide working edge
that is used to cut macadam, frozen ground,
or extremely hard earth, but is not for break­
ing concrete.
The tamper is a 5­ to 7­inch diameter steel
pad mounted on a piece of 1 1/4­inch hexagonal
tool steel.
The sheeting driver is made of two steel
angles and an impact pad that transmits the
blow to the wood or metal sheeting that is
being driven. It is used for driving wood or
metal sheeting up to 2 inches thick.
To operate­­
Hold the paving breaker down while it
is in operation, but use only sufficient
pressure to guide the tool and keep it in
place.
For optimum output, breakers should be
used in tandem.
Leaning heavily on the tool results in
less work, and slows the output of the
tool. That is, it shortens the stroke of
the tool.
Only small cuts (4 to 8 inches) should
be taken.
When working in nonreinforced concrete
with a moil point, based on 6­ to 8­inch
depths, production will range from 50
square feet per hour in large areas to 12
square feet per hour in narrow cuts. In
reinforced concrete, production may drop
to 50 square feet per 8­hour shift.
The operating technique for the tamper
is the same as the operation of the back­
fill tamper described in paragraph 22,
except that this tamper (paving breaker
attachment) can compact up to 8­inch
lifts of earth.
Observation of the following maintenance
indicators will aid in keeping the paving
breaker operable.
Do not attempt to drill holes with the
moil point. The moil point is a breaking
device.
Attempts to drill holes with it will result
in breakage of the point.
Use correct size shanked tools; improper
shank sizes will reduce the effectiveness
of the blow and will cause damage to the
paving breaker.
If a moil point becomes stuck, take the
paving breaker off and by using another
point break the stuck point free.
Shut off the tool when the moil point
breaks through the material. This will
prevent the front head from bouncing on
the concrete and thus eliminate breakage
of the retainer bolt.
Use the chisel point for its designed use
only.
If the chisel point is used for breaking
concrete, etc., the point will be damaged
beyond repair.
4­9
Keep all nuts tight.
Check the airhose to paving breaker
connections to assure that no air is es­
caping.
For safe operation­­
Hold the paving breaker firmly and plant
feet firmly while operating.
Always bleed the airhose when stopping
operations for any length of time.
Wear goggles when operating the paving
breaker to protect eyes from pavement
chips and dust.
Keep the work area clear of broken ma­
terial.
24. PAVING BREAKER, 25­LB
The paving breaker, 25­lb is a medium­
weight pneumatic tool designed for spading,
trimming, cutting, or picking clay, hardpan,
or frozen ground too hard for the use of a
manual digging tool such as the ordinary
hand spade or pick.
The breaker weighs 18­25 pounds, has an
air requirement of 35 cfm, and a recom­
mended air pressure of 80­90 psi.
Three attachments are normally issued
with this 25­pound paving breaker­­the
moil point, pick, and spade. In some cases,
a metal drum ripping tool may be issued for
opening 55­gallon drums.
The moil point consists of a 15­inch straight
length of 1­inch diameter tool steel pointed
on one end, with a collar and a 7/8­inch hex­
agonal shank 2 3/4­inches long. It is used as
a light demolition tool on masonry, brick,
concrete, or other material.
The moil point can often be used in
narrow, awkward places where there is
insufficient room to swing a hand pick.
The pick has a blade 3 inches wide by 8
inches long with a pointed cutting end. It is
used for digging into frozen ground, cemented
gravel, or other materials too hard to be
penetrated by the clay spade.
The spade, commonly called the clay spade,
is shaped like a garden spade, and is 5 1/2
inches wide by 8 inches long. It is used for
digging trenches, preparing footings or foun­
dations, digging caissons, driving tunnels, or
doing any general digging too difficult and
slow for an ordinary hand spade.
The metal drum ripping tool has a cutting
blade 1 inch wide, topped by an extended
snubnose 5/8­inch thick. There are two types:
Type I is used to cut heads from metal
drums. To do this, the nose of the rip­
ping tool is curved to allow it to more
easily follow the curvature of the head
on the drum.
Type II is used to split metal drums
lengthwise, so it has a straight instead of
a curved nose.
The operation of the paving breaker, 25­
pound and attachments is essentially the same
as that for like items used with the paving
breaker, 80­pound.
Preventive maintenance regarding the
breaker consists basically of the care of the
tool retainer.
Two flat surfaces ground on the hammer
permit the repeated blasts of air to clean
foreign matter out of the cylinder and
tool retainer.
The front head group is the tool retainer.
It includes the tool retainer body which
is bolted to the cylinder body; the rubber
bumper which absorbs shock; and the
collar and attachment retainer.
Particular attention should be given to
the tool retainer assembly. Dirt and other
abrasive materials get into the bottom
of the retainer and cause excessive wear.
The major portion of this wear can be
prevented if the operator does not allow
the tool to penetrate above the wide por­
tion of the clay spade.
To operate safely­­
Keep the airhose connections tight.
Keep exhaust away from the body.
4­10
25. ROCK DRILL
The rock drill is a handheld, piston­rotary­
type unit primarily designed as a hard rock
drill; however, it is equally efficient in soft
and medium formations as well. It is used
primarily for vertical drilling. If, however,
large numbers of horizontal holes are re­
quired, some mechanical means must be de­
vised for holding the drill in place. The drill
weighs 57 pounds, has an air requirement of
95 cfm, and a recommended air pressure of
80­100 psi. Hollow steel drill rods are issued
in 2­, 4­, 6­, 8­, and 10­foot lengths.
Drill bits are issued in diameter sizes of
1 5/8, 1 3/4 and 2 inches.
To operate­­
Place bit between heels of boots and lean
tool slightly forward.
Start drill at a slow speed, half throttle,
until the hole is approximately 1 inch
deep.
Step back from drill and hold tool in
vertical position, then push the throttle
lever down to full throttle.
Blow out the hole periodically by en­
gaging exhaust valve.
Bent steels should not be used. They not
only cause damage to the drill, but us­
ually result in a stuck bit and lost pro­
duction.
Preventive maintenance requires that OE
10 below 32 degrees, and OE 30 above 32
degrees be used in the oil reservoir; and that
oil be checked every 2 to 3 hours of continued
operation.
For safe operation, never straddle hose.
Check air connections before and during
` operations.
Wear goggles.
26. SUMP PUMP
The sump pump is a small capacity pump
that is handy for use on small jobs where an
air compressor is available. It can be run
completely submerged when an exhaust line
is used. The pump may be rated at 175 gal­
lons per minute against a 25­foot head or up
to 150 gallons per minute against a 150 foot
head. It may be either a class 1 pump for
transferring sewage and sludge, or a class 2
pump for transferring petroleum products.
The pump weighs 50 pounds, has an air re­
quirement of 100 cfm, and a recommended
pressure of 80­90 psi.
During operation, keep the sump pump in­
let strainer clean and free of debris.
Keep the pump away from mud bottoms
and clean it as often as necessary to as­
sure maximum efficiency.
Keep the exhaust line outlet above the
water level.
There are no maintenance problems in­
herent with the sump pump; however­­
If silt and dirt are left in the pump after
use, it will cause the impeller to stick
and will require disassembly and clean­
ing before it can be used again.
If water is allowed to get into the pump
through the exhaust port, it will cause
failure of the grease seals.
When idle, the pump should be drained
of water.
Use only water pump grease in the fit­
tings on the sump pump.
To be safe, shut off the exhaust pressure
from the line before disconnecting the line
from the tool.
Never kink the hose to stop the air flow.
Keep the clamps on the hose tight.
Be sure the airhose is suitable to with­
stand the pressure required for the tool.
27. AIR LINE OILER
The air line oiler is a reservoir of either a
pint or a quart capacity which is placed in
the air line directly in front of the air tool
for the purpose of lubricating the tool. As
the air passes through the oiler it picks up
the oil which is carried into the tool. The
amount of oil entering the air stream is
4­11
controlled by an adjustable needle. Oilers
occur in both directional and nondirectional
types. The arrow should be pointed in the di­
rection of air flow when connected in the line.
NOTE: Use the air line oiler or the tool
oil reservoir for lubrication but
never use both at the same time.
28. MAINTENANCE OF PNEUMATIC TOOLS
Two items are important in the mainte­
nance of a pneumatic tool. These are lubri­
cation and air pressure.
To check for proper lubrication of a
pneumatic tool, pass a piece of paper
in front of the tool exhaust port. If a
thin film of oil accumulates on the paper,
the tool is being properly lubricated. If
drops of oil appear on the paper or if
oil is foaming around the exhaust port,
this indicates overlubrication. If no oil
appears, the lubrication device should be
checked immediately.
Each tool requires a specified volume of
air at a specified pressure. If volume and
pressure are allowed to drop excessively,
considerable damage will be done to the
tool. When a pneumatic tool job is being
inspected, check for air leaks in hose or
around air connections and listen to and
observe the tool in operation. If a tool
appears to be operating sluggishly or
appears to be surging (detected by er­
ratic operation), it indicates either too
much or too little pressure. The tools
should never be operated with less than
70 or over 100 pounds per square inch
at the tool. Check the air pressure gage
on the air compressor and if it continual­
ly remains below 70 pounds per square
inch this indicates overloading of the
unit (too little pressure at the tool), and
should be corrected.
Section V. MIXING, PLACING, CURING, AND FINISHING OF CONCRETE
29. MIXING
Mixing is generally done by machine but
some hand mixing is invariably necessary. A
clean surface is required for this purpose.
Ordinarily a wooden platform with close
joints, to prevent loss of mortar, is used. The
platform should be leveled before mixing is
started. A clean, even paved surface will also
serve the purpose of a mixing platform.
The measured quantity of sand is placed
on the bottom, the cement is spread over
the sand, and then the coarse aggregate
is spread on top.
Either a hoe or a square pointed D­handle
shovel can be used to mix the materials.
The dry materials should be turned at
least three times until the color of the
mixture is uniform.
Water is added slowly while the mixture
is turned again at least three times.
Water is gradually added until the proper
consistency is obtained.
When two men are mixing, they should
face each other, working their way
through the pile and keeping the shovels
close to the surface of the platform while
turning the materials.
One man can mix 1 cubic yard of con­
crete by hand in about an hour, but this
is not an economical method of mixing
concrete in batches of over 1 cubic yard.
Power concrete mixers are available in
several sizes and types. A mixer will normally
produce a batch about every 3 minutes, in­
cluding charging and discharging.
The 16S concrete mixer is a self­contained
unit capable of producing 16 cubic feet of
concrete, plus a 10 percent overload, per
batch. The hourly production capacity will
vary between 10 and 15 cubic yards depending
4­12
on the efficiency of the personnel, support
equipment available, and the correct utiliza­
tion of charging and discharging methods. It
can handle aggregates up to 3 inches without
damage.
Methods used to obtain maximum output
from the 16S mixer are­­
Sand, gravel, and cement stockpiles
should be located as close to the mixer as
practicable.
The mixer should be level. Leveling may
be accomplished by digging in the wheels,
if necessary.
The skip of the mixer may be dug in to
facilitate loading, particularly when
wheelbarrows are to be used.
When wheelbarrows are used in charg­
ing the mixer or in placing the mixed
concrete, plank runways should be used.
Such runways accelerate materials han­
dling.
In charging the skip, gravel or rock
should be loaded first, the cement second,
then enough sand to cover the entire
batch. The gravel scours the skip bottom
and carries the entire load into the mix­
ing drum. The sand cover prevents ex­
cessive loss of cement dust as the batch
enters the drum.
Water should begin to enter the drum
about 3 seconds before the dry materials
are charged into the drum. The early
addition of water aids in cleaning the
drum and results in a faster, more ho­
mogeneous mix. When all aggregate and
water have been added, the batch should
be mixed for a minimum of 1 minute.
The mixer should be kept clean. At the
beginning of each day's operations the
machine should be coated with form oil
to prevent cement or mix from sticking
to the paint or bare metal. Each time
the mixer is shut down, a half batch of
gravel or of stone and water should be
run through the machine for approxi­
mately 5 minutes in order to loosen any
concrete caked in the drum. The entire
machine should be washed, cleaned, and
reoiled after each day's operation and
after the termination of a project. Never
pound the skip bottom or the drum to
loosen materials, because pounding may
cause dents and bumps around which
cement or mix may form.
During cold weather, the water tank,
pump, and lines must be drained each
time the mixer is shut down to prevent
possible damage from freezing.
Note: The designation 16SM for some
16­cubic foot capacity mixers re­
fers to a mortar mixing capability
in addition to a concrete capability.
Measuring the mix materials may be by
weight or volume.
Measurement by weight is the most re­
liable method, since the accuracy of
volume measurement depends on the ac­
curacy of an estimate of the amount of
bulking which varies according to the
moisture in the sand. However, measure­
ment by volume is more practical under
expedient conditions. On comparatively
small jobs the aggregate can be weighed
on platform scales. The scales should
be set on the ground and runways con­
structed so that a wheelbarrow can be
run onto one side of the scale and off the
other. With practice it is possible to
fill a wheelbarrow so accurately that it
is seldom necessary to add or remove
material to obtain the correct weight.
The amount of aggregate placed on each
wheelbarrow should be the same and the
quantity per batch should be supplied by
an even number of wheelbarrow loads.
Hence, the wheelbarrow may not be
loaded to capacity each time.
Measuring by volume can be done by
means of a 1­cubic foot measuring box
built on the job. The inside of the box
should be marked off in tenths of a cubic
foot. The GI bucket can also be used as
a measuring device; it contains 0.467
cubic foot which may be considered one­
half cubic foot.
4­13
If wheelbarrows are to be used to carry
the aggregate from the storage pile to
the mixer, the following procedure, based
on a 3­cubic foot wheelbarrow, should
be used.
Assume that the proportions by volume
are 1:2:3 and each batch is to contain
three sacks of cement. Use the 1­cubic
foot measuring box to load 2.0 cubic feet
of sand in the wheelbarrow. Draw a line
around the inside of the wheelbarrow at
the level of the sand. Three wheelbarrows
filled to this level will then be used per
batch. The coarse aggregate can be
measured directly from the wheelbarrow.
Water for mixing must be accurately mea­
sured for each batch. When using the mixer,
hook up the water supply at the hose coupling
on the mixer.
Set the water check drum, then set the
water tank for desired amount of water.
If the mixer is not equipped with an
automatic measuring device, a pail,
marked for gallons and fractions, may be
used to measure the water. In any event,
mixing water should be measured care­
fully.
There are two ways of charging concrete
mixers, by hand and with the mechanical
skip. The 16S mixer is equipped with a
mechanical skip. The cement, sand, and
gravel are placed in the skip and then dumped
into the mixer together while the water runs
into the mixing drum on the side opposite
the skip. The mixing water is measured from
a storage tank on top of the mixer a few
seconds before the skip is dumped to wash
the mixer between batches. The coarse ag­
gregate is placed in the skip first, the cement
next and the sand is placed on top to prevent
excessive loss of cement as the batch enters
the mixer.
When the material is ready for discharge
from the mixer, the discharge chute is moved
into place to receive the concrete from the
drum of the mixer. In some cases, dry con­
crete has a tendency to carry up to the top
of the drum and not drop down in time to
be deposited on the chute. Very wet concrete
may not carry up high enough to be caught
by the chute. This condition can be corrected
by adjusting the speed of the mixer. For very
wet concrete, the speed of the drum should
be increased and for dry concrete, it should
be slowed down.
The mixing time is determined from the
time the water is added to the mixture. All
mixing water should be added in the first
quarter of the mixing period. The minimum
mixing time per batch of concrete is 1 minute
unless the batch exceeds 1 cubic yard. An
additional 15 seconds of mixing time is re­
quired for each additional 1/2 cubic yard of
concrete or fraction thereof.
The consistency of concrete is measured
by the slump test. The aim in controlling
the slump is to control directly the consis­
tency and workability necessary for proper
placement.
30. PLACING
Concrete should be deposited in even hori­
zontal layers and should not be puddled or
vibrated into place. Each layer should be
soft when a new layer is placed upon it. The
layers should be from 6 to 24 inches in depth
depending on the type of construction. To
prevent honeycombing or avoid spaces in the
concrete, the concrete should be vibrated or
spaded. Vibration periods of 5 to 15 seconds
with the immersion­type vibrator for each
penetration is usually sufficient. When over­
vibration occurs, the surface concrete not
only appears wet, but it actually consists of
a layer of mortar containing practically no
coarse aggregate.
On large pours, to avoid excess pressure
on forms, the rate of filling should not exceed
4 feet per hour measured vertically, except
for columns. In order to avoid cracking dur­
ing settlement, an interval of at least 4 hours,
preferably 24 hours, should elapse between
completion of columns and walls and the
placing of slabs, beams, or girders supported
by them.
31. CURING
The water content of fresh concrete is con­
siderably more than enough for hydration of
4­14
the cement. However, an appreciable loss of
this water, by evaporation or otherwise, after
initial set has taken place will delay or prevent
complete hydration. The object of curing is
to prevent or replenish the loss of necessary
moisture during the early, relatively rapid
stage of hydration.
The usual procedure for accomplishing this
is to keep the exposed surface continuously
moist by spraying or ponding, or by covering
with earth, sand, or burlap maintained in a
moist condition.
Early drying must be prevented or the
concrete will not reach its full potential quali­
ty. In warm, dry, windy weather, corners,
edges, and surfaces become dry more readily.
If these portions are prevented from drying,
and fully develop their hardness and quality,
interior portions of the concrete will have
been adequately cured.
32. FINISHING OF CONCRETE
After a floor slab, sidewalk, or pavement
has been placed, the top surface is rarely at
the exact elevation desired. The process of
striking off the excess concrete in order to
bring the surface to the right elevation is
called screeding. Other finishing operations
include floating, troweling, brooming, and
rubbing. Screeding operation can begin as
soon as the concrete has been placed.
Prior to screeding the concrete should
be vibrated to lower larger sized ag­
gregate to avoid interference with the
screed.
A templet with a straight lower edge if
a flat surface is required, or curved if
a curved surface is required, is moved
back and forth across the concrete with
a sawing motion. The templet rides on
wood or metal strips that have been
established as guides. There should be
a surplus of concrete against the front
face of the templet which will be forced
into the low spots as the templet is moved
forward. If there is a tendency for the
templet to tear the surface, the rate of
forward movement of the templet should
be reduced or the bottom edge should be
covered with metal. In most cases, this
will stop the tearing action. Such pro­
cedures are necessary when air­entrained
concrete is used because of the sticky
nature of this type of concrete.
It is possible to hand screed surfaces
up to 30 feet in width but for efficient
screeding it is best not to go beyond 10
feet.
Three men, excluding a vibrator opera­
tor, can screed approximately 200 square
feet of concrete per hour. Two men
operate the screed and the third man
pulls excess concrete from the front of
the screed.
Sometimes, it is necessary to screed the
surface twice to remove the surge of
excess concrete caused by the first
screeding.
If a smoother surface is required than the
one obtained by screeding, the surface should
be worked sparingly with a wood or metal
float or finishing machine.
This process should take place shortly
after screeding and while the concrete
is still plastic and workable.
High spots are eliminated, low spots
filled in, and enough mortar is brought
(floated) to the surface to produce the
desired finish.
The concrete must not be overworked
while it is still plastic, to avoid bringing
an excess of water and mortar to the
surface. Such material will form a thin
weak layer that will scale or wear off
under usage.
Where a coarse texture is desired as the
final finish, it is usually necessary to float
the surface a second time after it has
partially hardened so that the required
surface will be obtained.
In slab construction long­handled wood
floats are used.
The steel float is used the same way as
the wood float but it gives the finished
4­15
concrete a much smoother surface. Steel
floating should begin when the water
sheen disappears from the concrete sur­
face, to avoid cracking and dusting of
the finished concrete. Cement or water
should not be used to aid in finishing the
surface.
If a dense, smooth finish is desired, floating
must be followed by steel troweling at some
time after the moisture film or sheen disap­
pears from the floated surface and when the
concrete has hardened enough to prevent fine
material and water from being worked to the
surface. This step should be delayed as long
as possible. Excessive troweling too early
tends to produce crazing and lack of durabili­
ty; too long a delay in troweling results in a
surface too hard to finish properly. The usual
tendency is to start to trowel too soon.
Troweling should leave the surface smooth,
even, and free of marks and ripples.
Spreading dry cement on a wet surface to
take up excess water is not good practice
where a wear­resistant and durable surface
is required.
Wet spots must be avoided if possible; when
they do occur, finishing operations should not
be resumed until the water has been absorbed,
has evaporated, or has been mopped up.
A surface that is fine­textured but not
slippery may be obtained by troweling lightly
over the surface with a circular motion im­
mediately after the first regular troweling.
In this process, the trowel is kept flat on the
surface of the concrete.
Where a "hard steel­troweled finish" is re­
quired, the first regular troweling is followed
by a second troweling after the concrete has
become hard enough so that no mortar ad­
heres to the trowel and a ringing sound is
produced as the trowel passes over the sur­
face. During this final troweling, the trowel
should be tilted slightly and heavy pressure
exerted to thoroughly compact the surface.
Hair cracks are usually due to a concentra­
tion of water and fines at the surface resulting
from overworking the concrete during finish­
ing operations. Such cracking is aggravated
by too rapid drying or cooling. Checks that
develop before troweling usually can be closed
by pounding the concrete with a hand float.
A nonskid surface can be produced by
brooming the concrete before it has thorough­
ly hardened. Brooming is carried out after
the floating operation.
For some floors and sidewalks where severe
scoring is not desirable, the broomed finish
can be produced with a hairbrush after the
surface has been troweled to a smooth finish
once.
Where rough scoring is required, a stiff
broom made of steel wire or coarse fiber
should be used. Brooming should be done in
such a way that the direction of the scoring
is at right angles to the direction of the
traffic.
A rubbed finish is required when a uniform
and attractive surface must be obtained, al­
though it is possible to produce a surface of
satisfactory appearance without rubbing if
plywood or lined forms are used.
The first rubbing should be done with
coarse carborundum stones as soon as the
concrete has hardened so that the aggregate
is not pulled out.
The concrete should then be cured until
final rubbing.
Finer carborundum stones are used for the
final rubbing. The concrete should be kept
damp while being rubbed. Any mortar used
to aid in this process and left on the surface
should be kept damp for 1 to 2 days after it
sets in order to cure properly. The mortar
layer should be kept to the minimum as it is
likely to scale off and mar the appearance of
the surface.
33. MACHINE FINISHING
Machine finishing is carried out at such
time as the concrete takes its initial set. The
concrete must, however, be in workable con­
dition at the time of the finishing operation.
The screeds and vibrator on the machine
finisher are set to give the proper surface
4­16
elevation and produce a dense concrete. In
most cases, there should be a sufficiently thick
layer of mortar ahead of the screed to insure
that all low spots will be filled. The vibrator
follows the front screed and the rear screed
is last. The rear screed should be adjusted
to carry enough grout ahead of it to insure
continuous contact between screed and pave­
ment. If forms have been set in good aline­
ment and firmly supported, and if the concrete
has the right workability, no more than two
passes of the machine should be required to
produce a satisfactory surface.
34. HAND FINISHING
Sometimes hand finishing behind the finish­
ing machine is necessary.
It is sometimes necessary also to use a
longitudinal float to decrease longitudinal
variations in the surface.
Such a float is made of wood, 6 to 10 inches
wide and 12 to 18 feet long, fitted with a
handle at each end and operated by two men
on form­riding bridges. The float is oscillated
longitudinally as it is moved transversely. A
10­foot straightedge pulled from the center
of the pavement to the form will remove any
minor surface irregularities and laitance.
Unless considerable care is exercised as the
straightedge or float approaches the form, it
will ride up on the concrete resulting in a
hump in the surface, especially where con­
struction and expansion joints occur. The
surface should have no coating of weak mor­
tar or scum that will later scale off.
35. FINAL FINISHING
After the water sheen disappears, the final
surface finish is applied by dragging a clean
piece of burlap longitudinally along the pave­
ment strip. This is known as belting and is
done by two men, one on each side of the
forms.
A nonskid surface is obtained by stroking
with bassine brooms having fibers about 4 1/2
inches long. The grooves cut by the broom
should not be over 3/16 inch deep. All corners
of the paving should be rounded with an
edging tool.
Expansion joints must be cleaned out and
prepared for filling.
EXERCISES
First requirement. Multiple­choice exer­
cises 1 through 6 are designed primarily to
enable you to show what you have learned
about earthmoving equipment.
1. Your squad has one dump truck
with which to haul earth from a small
excavation project. What is the rated
capacity of the truck's dump body?
a. 1 1/2 cubic yards
b. 3 tons
c. 5 cubic yards
d. 9 tons
2. Dozer blades vary in size and
are designed to perform different earth­
moving functions. What two adjust­
ments can be performed on the straight
blade on a crawler tractor?
a. tilt and pitch
b. angle and pitch
c. tilt and curve
d. curve and angle
3. The moldboard of the grader is
fastened to the circle. It consists of the
cutting edges and end bib. By ro­
tating the circle the moldboard may be
placed at any angle within a complete
circle. Considering this capability,
which of the following tasks would you
say the grader can perform?
4­17
a. ditching up to 5 feet deep
b. making sidehill cuts
e. mixing and spreading
d. loading or digging
4. The crane­shovel with its vari­
ety of front end attachments is the most
common type of lifting and loading
equipment. Which of the following are
a part of the basic crane­shovel?
a. truck mounting and shovel front at­
tachment
b. truck mounting and revolving su­
perstructure
e. revolving superstructure and shovel
front
d. carrier and one of the basic attach­
ments
5. A major task in any construc­
tion operation is the handling of con­
struction supplies and excavating.
Which of the following items of lifting
and loading equipment would you con­
sider as most effective for outloading
aggregate into dump trucks from sev­
eral stockpiles, approximately 150 feet
apart?
a. crawler mounted shovel
b. crawler mounted backhoe
e. truck mounted clamshell
d. wheel mounted scooploader
6. The standard length boom for
a truck­mounted crane is 30 feet. When
raised for operation, what is the mini­
mum safe working distance (in ft) from
69 KV lines for any part of boom
equipment?
a. 5 c. 25
b. 12 d. 40
Second requirement. Multiple­choice exer­
cises 7 through 14 deal with utilization of air
compressor tools.
7. Compressed air is used to in­
flate rubber equipment, to spray paint,
to operate pneumatic tools, to power
the guidance systems of certain mis­
siles, to clean equipments to perform
various jobs around maintenance shops,
and to furnish air for underwater
divers. What two requirements are de­
manded from an air compressor to op­
erate pneumatic tools?
a. specified volume of air (cfm) and
an air receiver tank
b. pressure control system and air
pressure of 80­100 psi
c. specified volume of air (cfm) at a
specific pressure (psi)
d. specific pressure (psi) and an in­
tercooler
8. Your squad has been assigned
the task of clearing a grove of trees.
What is the maximum diameter in
inches you can normally cut with the
standard pneumatic chain saw?
a. 12 c. 24
b. 18 d. 36
9. What are the lengths, in inches,
of auger bits used with the wood borer?
a. 6 and 8 c. 12 and 36
b. 12 and 14 d. 24 and 36
10. The head of the backfill tamper
is attached to the end of the piston
shank which is tapered to fit the socket
in the head. The large flat area of the
head provides the tamping surface. For
best results, which of the following ma­
terials requires that you wrap the
tamper head with burlap?
a. gravel c. asphalt
b. loose earth d. silt
11. The need for patching oil bi­
tuminous pavements occurs because of
base or surface failures which are re­
flected in the surface of the pavement.
4­18
Your squad has the mission of patching
pavement. The method is to cut back
well beyond the apparent limits of the
broken area. Which of the following
tools would you use to cut back the
macadam?
a. crowbar
b. paving breaker
c. clay digger
d. posthole auger
12. The work output of the men
on the job is materially affected by the
way the job is organized and super­
vised. To receive optimum output from
the paving breakers, how should they
be used?
a. in close areas
b. singly
c. in tandem d. horizontally
13. Holes are drilled for various
purposes, such as to receive charges of
explosives, for exploration, the injec­
tion of grout, or stabilizing bolts and
cables. Within practical limits the equip­
ment which will produce the best overall
efficiency should be used. Which of the
following tools would be best for drilling
a 1 5/8­inch, 5­foot hole in quarry rock?
a. 80­lb paving breaker with moil point
b. 25­lb paving breaker with moil point
c. 25­lb paving breaker with 6­foot
drill steel
d. rock drill with 6­foot steel drill rod
14. Two items are important in the
maintenance of a pneumatic tool. These
are lubrication and air pressure. In
order to check a pneumatic tool for
proper lubrication, what should you see
on a piece of paper after you pass it in
front of the exhaust port?
a. a thin film of oil
b. drops of oil
c. no oil mark
d. a burn
Third requirement. Multiple­choice exer­
cises 15 through 20 provide an opportunity
for you to show that you understand mixing,
placing, curing, and finishing of concrete.
15. Established and well­defined
concrete mixing procedures must be fol­
lowed if the finished concrete is to be
of good quality. During operation of
a 16S mixer, when would you introduce
water into the mixing drum?
a. before the dry materials
b. at the same time as the dry ma­
terials
c. intermittently with dry materials
d. after the dry materials
16. Overmixing is objectionable be­
cause the grinding action increases
fines, which require more water to main­
tain consistency of concrete. Also, over­
mixing may drive out entrained air.
What is the minimum mixing time for
the 16S mixer when the batch does not
exceed one cubic yard?
a. 30 seconds c. 1 minute
b. 45 seconds d. 1 1/2 minutes
17. Good concrete placing and com­
pacting techniques produce a tight bond
between mortar and coarse aggregate
and assure complete filling of the forms.
Which of the following practices should
be used to produce good concrete?
a. each layer should be hard before
placing a new layer upon it
b. each layer should be soft when a
new layer is placed upon it
c. concrete for large pours should be
placed at a rate of at least 6 feet
per hour
4­19
d. one or two hours should elapse be­
tween completion of columns and
walls and the placing of slabs,
beams, or girders supported by
them
18. Concrete exposed to dry air
from the time it is placed is about 50
percent as strong at 6 months as con­
crete moist cured 14 days before being
exposed to dry air. What is a conse­
quence of concrete drying too early?
a. it is not smooth
b. it does not reach its full potential
quality
c. volume is increased approximately
15 percent
d. volume is decreased approximately
15 percent
19. From an economic standpoint,
the top surface of a structure or por­
tion of a structure can be finished to
serve as a floor surface. Which of the
following would you use to produce the
smoothest surface?
a. screed
b. wood or metal float
c. broom
d. burlap drag
20. Hand finishing with floats be­
hind the finishing machine is often more
harmful than beneficial. Which of the
following is a result of floating behind
the machine?
a. finish is too smooth
b. too many ridges are left
c. scaling is possible
d. it tends to leave too many surface
irregularities
LESSON 5
CONSTRUCTION PLANNING
CREDIT HOURS _______________________2
TEXT ASSIGNMENT ____________________Attached memorandum.
MATERIALS REQUIRED__________________None.
LESSON OBJECTIVE ___________________To teach you the fundamentals of
construction
drawings, symbols, sketches, bills of ma­
terials, specifications and materials
takeoff.
______________________________________________________________________________
ATTACHED MEMORANDUM
Section I. CONSTRUCTION DRAWINGS
1. DRAWINGS
Drawings are graphic representations of
buildings, structures, or areas that give most
of the information necessary for proposed
construction.
Architectural drawings represent factors
such as overall size, appearance, arrangement
of internal space, and number, size, and kind
of doors, windows, and fittings.
Engineer (structural) drawings reflect the
mechanical systems of a building such as
plumbing, lighting, heating, ventilating, and
air conditioning. They also reflect the strength
of the supporting members.
Utility drawings show the details of con­
struction for the following service facilities
outside buildings:
Electrical distribution systems.
Water supply and distribution systems.
Sewage systems and disposal plants.
Liquid fuel systems.
Construction drawings are obtained by
combining both architectural drawings and
engineer drawings into a set for a particular
structure.
Production drawings describe equipment,
parts, or articles that are suitable for pro­
duction in quantity.
2. LINE CONVENTIONS
In order to include all the necessary infor­
mation on a drawing in a meaningful manner,
different types and weights of lines are used
to represent the features of an object. The
meaning of a line with certain characteristics
has been standardized, and will be the same
on any drawing. The line conventions most
encountered in construction drawings are
described below and shown in figure 1. Ap­
plication of these line conventions is demon­
strated in figure 2.
Visible lines are heavyweight unbroken
lines used for the primary feature of a draw­
ing. For drawings of objects, this line con­
vention represents the edges, the intersection
of two surfaces, or the surface limit that is
visible from the viewing angle of the drawing.
This line is often called the outline.
Hidden lines are medium weight lines of
evenly spaced short dashes used to represent
an edge, the intersection of two surfaces, or
the surface limit which is not visible from
the viewing angle of the drawing.
A thin (light) line composed of alternate
long and short dashes of consistent length is
called a center line. It is used to signify the
center of a circle or arc and to divide an
object into equal or symmetrical parts.
5­1
5­2
5­3
Dimension lines are solid continuous lines
terminating in arrowheads at each end. Di­
mension lines are broken only to permit
writing in the dimensions. On construction
drawings the dimension lines are unbroken.
The points of the arrowheads touch the ex­
tension lines which mark the limits of the
dimension. The dimension is expressed in
feet and inches on architectural drawings and
in feet and decimal fraction of a foot on engi­
neering drawings.
An extension line is a thin (light) unbroken
line that is used to indicate the extent of the
dimension lines. The extension line extends
the visible lines of an object when it is not
convenient to draw a dimension line directly
between the visible lines. There is always a
small space between the extension line and
the visible line.
A leader is a thin (light) line terminated
with an arrowhead or dot that is used to
indicate the part or feature to which a num­
ber or other information refers.
A medium weight line made of long dashes
broken by two short dashes is called a pan­
tom or datum line and indicates one of three
things: the relative position of an absent
part, an alternative position of a part, or
repeated detail which is not drawn.
Stitch lines are medium lines made of short
dashes evenly spaced and labeled used to in­
dicate stitching or sewing.
Break lines are thin (light) lines inter­
rupted by a Z­shaped symbol. The break line
indicates that the object has been shortened
to save space on the drawing. The true length
is indicated by the dimension specified. The
short break line convention varies with shape
and material and indicates that part of the
object has been cut away to show section
detail or hidden features.
Cutting plane lines are a pair of short,
heavy lines with arrowheads projected at 90ø
used to indicate the cutting plane when a
drawing includes a section view. Letters (AA,
BB, etc.) are usually placed at the arrow­
heads to identify the section view. The arrow­
heads show the viewing direction of the sec­
tion view. Where necessary, the section lines
may be connected by a line of short, heavy
dashes indicating the exact path of the cut­
ting plane.
When a drawing includes a section, the
surface or surfaces which are in the cutting
plane are indicated by section lines. When
the object sectioned is all one material, the
section lines are usually closely spaced
parallel lines of medium thickness. Where
5­4
5­5
different materials are involved, different sec­
tion conventions are used to distinguish be­
tween them.
3. SYMBOLS
Just as there are different types of lines
on drawings, so also there are different
symbols for different materials. The symbols
shown in figure 3 are the conventional, sym­
bols used to represent the more common types
of materials.
4. PROJECTIONS
An object can be viewed and therefore
drawn from an infinite number of positions.
Some views are easier to draw and interpret
than others.
An orthographic projection is commonly
used to present an object on a drawing.
In this projection, the object is presented
as if it were viewed through a trans­
parent box (fig. 4).
The projections of the object on the sides
of the box are the views seen by looking
straight at the object through each side.
If the outlines are scribed on each sur­
face, and the box is opened and laid flat,
the result is a six­view, orthographic
projection drawing.
As a general rule most drawings are pre­
sented in three views. The most common
three­view drawing (fig. 5) arrangement
shows the front, top, and right side view of
an object.
In a three­view drawing, the front view
shows the most characteristic feature of
the object.
Note in figure 5 that the right side or
end view is projected to the right of the
front.
All the horizontal outlines of the front
view are extended horizontally to make
up the side view and all the vertical out­
lines of the front view are extended
vertically to make up the top view.
Note: By studying the drawing you
should obtain the following infor­
mation about the object: the shape
of the object, its overall length
(2 1/8 inches), its width (1 1/2 inches),
and its height (1 3/8 inches). It is
notched 1 1/8 inches from the right
side and 7/8 inch from the bottom.
5­6
After having studied each view of
the object, you should be able to
visualize the object as it appears in
figure 6.
If a hole is drilled in the notched portion of
the object, the drawing would appear as in
figure 7. The position of the hole is indicated
by hidden lines in the front and side view
and as a circle in the top view. The location
of the center of the drilled hole is indicated
by a center line.
Note: Two views can sometimes be used­
to sufficiently describe a simple ob­
ject.
Isometric projection is a three dimensional
representation of an object. In figure 6, the
notched box formed by the combination of
the three orthographic projections forms an
isometric projection.
5. FUNDAMENTALS OF INTERPRETATION
The objects used for illustrations thus far
have been simple, and interpretation of the
drawings nearly obvious. More complex or
irregular drawings may require more effort
to interpret. The principles introduced here
will enable you to interpret most properly
prepared drawings.
The orthographic projection principles are
fundamental to all fields and a thorough un­
derstanding of them is necessary if you are
to read any type of physical print.
The fundamental step in interpreting a
drawing is relating the different views. If
you pick a point on a front view, the same
point on the right side view will be directly
to the right of it. Similarly, the same point
on the top view will be directly above the
point on the front view.
These relationships are illustrated in 1 ,
figure 8, by the horizontal and vertical datum
lines between the views. The same relation­
ship exists between the top and right side
views but is not obvious because they are not
hinged together.
If the outside edges of both views are
extended horizontally or vertically until they
cross, as in 2 , figure 8, and a line is drawn
connecting these points of intersection, the
relationship can be seen. The line connecting
the points of intersection will be at a 45ø
angle with the horizontal. All other points
in the views can be related by bending their
project line at this 45ø line.
If the same point appears on three views,
the three occurrences will be related as shown
by point 1 in 2 , figure 8. On complex drawings
it is often helpful to draw this 45ø line to
5­7
be sure you are looking at the same point on
all three views when interpreting the drawing.
Example 1: Figure 9 is a three­view draw­
ing (orthographic projection) of an object,
along with an isometric outline of a box with
the same overall dimensions of the object.
You are to develop the isometric projection
of this object by interpreting the three views
and completing the basic outline given.
Solution: To develop the actual shape of
the object proceed as follows:
First note that point h in the front view,
point e in the side view, and point g in
the top view correspond to point n on
the isometric.
Point a is common to all three views and
is shown as a on the isometric.
Point b in the front view, c in the top
view and d in the side view correspond
to isometric point q.
Point f in the top view corresponds to m
of the isometric.
5­8
Point l in the side view and j in the front
view correspond to point p in the iso­
metric.
Finally, k in the side view corresponds
to r in the isometric.
Once the points of each view are related
to points of an isometric, interpretation
becomes a simple matter of connecting
the similar points on the isometric that
are connected in the views. In the front
view notice that j and h are connected
by a line. Also, in the isometric, n and p
are similarly connected.
Trace the isometric on a sheet of paper.
Proceeding as above, the following lines
can now be drawn on the isometric:
from a to r (a to k in side view)
from a to q (a to b, front view; a to c,
top; a to d, side)
from a to p ( a to j, front; a to l, side)
from a to n (a to h, front; a to g, top;
a to e, side)
from q to r (d to k, side)
from q to n (b to h, front; c to g, top;
d to e, side)
The tracing of the isometric should now
look like that shown in figure 10.
6. SECTIONS
Section views are used to give a clear view
of the interior or hidden features of
object which normally cannot be clearly ob­
served in conventional outside views.
A section view is obtained by cutting away
part of an object to show the shape and
construction at the cutting plane. The most
common position of the cutting plane is
through the longest dimension, or main longi­
tudinal axis and parallel to the front view
as shown in figure 11.
The part that is cut by the cutting plane
is marked with closely spaced, parallel
(section) lines.
The section lines indicate the surfaces
which were created by the cutting plane
and which do not exit on the uncut
object.
When two or more parts are cut in one
view, a different slant or style of section
line is used for each part.
Notice how the cutting plane is shown
on a drawing as illustrated in 1 figure 11.
The cutting plane in 2 illustrates where
the imaginary cut is made. The object
as it would look if it were cut in half is
shown in 3 . The section view as it would
appear on a drawing is shown in 4 .
When the cutting plane is a single con­
tinuous plane passing entirely through the
object, the resulting view is called a full­
section view ( 1 fig. 12). The cutting plane
is usually taken straight through on the main
axis or center line.
The cutting plane will not always be taken
completely through the object. 2 figure 12
shows a half­section. The cutting plane
passes only half­way through the object. This
is common practice for symmetrical objects.
The half­section permits both the internal
and external features to be shown and their
relationship to one another.
5­9
7. DIMENSIONS
The item you will be most concerned with
when reading prints is the dimensions.
As previously stated, dimensions on
architectural drawings are usually given
in feet, inches, and fractions of an inch.
Engineering drawings often give dimen­
sions in feet and decimal fractions of a
foot.
Metric dimensions are used on drawings
of European origin, most drawings re­
lated to optical equipment, and a growing
percentage of American machine draw­
ings.
Note: During construction, you should
use measuring instruments cali­
brated in the same system as used
on the construction prints to elimi­
nate the chance of error in con­
version.
5­10
There are two general types of dimensions
­­those indicating size and those indicating
location.
The overall dimensions of an object in­
dicate its size. Dimensions giving the
size of a component, the diameter of a
circle, the depth of a groove, or the
width of a keyway are size dimensions.
Location dimensions show the relative
position of two components or the ex­
treme limits of travel of a moving part.
They are given from center to center,
from center to surface, or from surface
to surface.
The placement of dimensions on a drawing
is not arbitrary. They are placed to indicate
which dimensions are specified in the design
of the object. Measurements for construction
should always be made from the points in­
dicated by the dimension lines on the print.
Sample Exercises. Figure 13 is a drawing of
a jig block. As a test of your ability to
visualize and interpret three­view drawings,
answer the following questions pertaining to
this figure. The answers are given at the end
of this lesson.
1. What kind of lines are J, O, W, X,
Y, and V?
2. What type of lines are Q and Z ?
3. What kind of lines are P and S?
4. What letter or letters denote(s) ex­
tension line(s)?
5. What letters in the top view denote
outlines or visible lines?
6. What surface in the top view repre­
sents surface A in the isometric?
7. Surface N in the front view repre­
sents what surface in the isometric?
8. Surface B is represented by what
surface in the front view?
9. Surface C is represented by what
surface in the top view?
10. Surface B is represented by what
letter in the top view?
11. What is the overall height of the
jig block?
12. What is the overall width of the jig
block?
13. What is the overall length of the jig
block?
14. What is the dimension of Z in the
side view?
15. What is the dimension of Q in the
side view?
16. What is the width of surface H?
17. What is the length of surface N?
18. What is the length of line W?
8. DRAWING FORMATS
A drawing not only provides information
about the size and shape of the object being
represented but also provides information
5­11
that enables the drawing to be identified,
processed, and filed methodically.
The systematic arrangement of the draw­
ing sheet to provide a consistent location
for this information is known as the format
of a drawing.
A typical title block as illustrated in figure
14 shows:
A ­­ The name and address of the pre­
paring agency
B ­­ The title of the drawing
C ­­ The drafting record
D ­­ The approval block
E ­­ The scale and specification number
F ­­ The drawing number and sheet
number
The scale block will indicate the scale on
the drawing either as a ratio (for example:
1/4 or 1:4 meaning 1 inch on the drawing
equals 4 inches on the object, or 12" = 1"
meaning 12 inches on the drawing equals 1
inch on the object) or as a graphic scale as
shown in figure 15.
Where the same scale is not used on all
parts of a drawing, the scale block may be
marked "as noted" or left blank, and the
scale noted underneath each part of the
drawing.
If graphic scales are used, several scales
may be shown with number (fig. 15) and the
appropriate scale number noted alongside
each part of the drawing.
Note: When reading drawings, always
follow the dimensions specified on
the drawing first, and use the scale
on the drawing only where no di­
mension is given.
The drawing number's purpose is to per­
mit quick identification.
5­12
If a drawing has more than one sheet
this information is included in the num­
ber block indicating the sheet number
and number of sheets.
The notes may list allowable substitutions,
special provisions for certain locations, addi­
tonal reference material, and so forth. The
notes must always be read before beginning
construction.
Notations on drawings or prints explaining
materials or construction methods which can­
not be indicated by symbols are called speci­
fications. Such specifications provide a means
of control of the quality of the materials and
workmanship. The emphasis should be on
the performance rather than on detailed
methods of manufacture.
It is usually necessary only to specify the
quality required, rather than to specify the
manner in which quality will be obtained. In
specifying structural steel it is necessary only
to specify the type of steel with reference to
the standard specifications which control its
manufacture. Type and grading of lumber
should be specified; and in the case of con­
crete, the desired ultimate compressive
strength at 28 days after placing should be
specified. Section II. CONSTRUCTION ESTIMATES
9. MATERIAL ESTIMATES
A bill of materials (BOM) is a tabulated
statement of requirements for a given project
showing piece number, name, description,
quantity, material, stock size and number,
and sometimes the weight of each piece.
Bills of materials for facilities of the Engi­
neer Functional Component System (EFCS)
are contained in TM 5­303, and some drawings
in TM 5­302 are accompanied by a simplified
bill of materials. In such cases, the estimator
should check the bill against the drawing and
specifications for any discrepancies. If al­
terations or modifications of the plans are
necessary, which is often the case for facili­
ties of the EFCS, the estimator will have to
make the required additions and/or deletions
to the accompanying bills.
When drawings and specifications for a
project are not accompanied by a bill of
materials, the estimator must do a materials
takeoff from the drawings and prepare the
bill of materials.
10. MATERIALS TAKEOFF
The first step in the preparation of a BOM
is the tabulation of a materials takeoff. The
takeoff usually is an actual tally and check­
off of the items shown, noted, or specified on
the construction drawings and specifications.
Both architectural and engineering plane
provide the means by which names of the
various items can be listed in order to make
up the materials takeoff.
Indicated or scaled dimensions of buildings,
structures, or utilities layouts are used to
determine material unit dimensions.
5­13
The materials takeoff tabulation should
include column headings for each of the fol­
lowing:
Item number.
Part­­Description of the item.
Number of pieces­­Total number of
pieces of the item in the complete ob­
ject.
Nominal size­­Taken from the notes
and specifications on the drawing.
Length in place­­Taken from the di­
mensions (or scale) of the drawing.
Standard length­­Length of material
available that will be used for the par­
ticular item.
Number of pieces per standard length­­
Number of pieces of the item that can
be obtained from the standard length
used.
Number of standard lengths­­Number
of standard lengths needed to obtain
the total number of pieces of the item.
Note: Parts are not combined unless size
and nomenclature are identical.
Development of the materials takeoff be­
gins with an examination of the plans to
determine what is needed. Each part is listed
and described in detail (Col 1 thru 5). This
data is taken directly from the drawing.
The next phase of a takeoff list is indi­
cating the standard lengths of lumber to use
for each wooden part (Col 6 thru 8).
For columns 6 and 7, it is necessary to
determine the standard length of ma­
terial from which the parts can be cut
and how many can be cut from the
length selected.
8­, 10­, 12­, 14­, 16­, 18­, and 20­foot
lengths of lumber are the standard
lengths.
The selected standard length is entered
in column 6.
The number per standard length (Col 7)
is developed by dividing the standard
length (Col 6) by the length in place
(Col 5).
The number of standard lengths (Col 8)
is obtained by dividing the number of
pieces (Col 3) by Column 7.
Example 2: Figure 16 is the construction
detail for a timber box culvert. Develop the
materials takeoff for this culvert.
Solution: After studying the plans, each part
must be listed. In the front view, begin your
tabulation from the top to the bottom, left
to right (or in any orderly fashion so that
no part is omitted). Beginning with the cap,
notice that it is 3 x 12 lumber (front view)
4'­0" long (side view). This entry is:
_____________________________________________________ (1) (2) (3) (4) (5)
Item Part Number Nominal Length
of pieces size in place
______________________________________________________ 1 Cap 10 3 X 12 4'­0"
______________________________________________________ Next, look at the collar. 2" x 10" material
is needed for this part. However, two dif­
ferent sizes are needed for this item; there­
fore, two separate entries are needed. The
short collar is 18" long and the long collar
is 4'­4" long (side view). These entries are:
______________________________________________________ (1) (2) (3) (4) (5)
Item Part Number Nominal Length
of pieces size in place
______________________________________________________ 2 Collar (short) 4 2" x 10" 1'­6"
3 Collar (long) 4 2" x 10" 4'­4"
______________________________________________________ Proceeding in the same manner for the
stringer, scab, and sill, the first five column
entries for the takeoff are:
_____________________________________________________ (1) (2) (3) (4) (5)
Item Part Number Nominal Length
of pieces size in place
_____________________________________________________ 1 Cap 10 3 x 12 4'­0"
2 Collar (short) 4 2 x 10 1'­6"
3 Collar (long) 4 2 x 10 4'­4"
4 Stringer 2 2 x 12 12'­0"
5 Scabbing 2 2 x 10 1'­6"
6 Sill 10 3 x 12 4'­0"
_____________________________________________________ The last three entries required some cal­
culations. In column 6 the shortest standard
length supplying the most pieces with the
least waste is normally chosen.
5­14
Continuing the example of the timber box
culvert let us proceed to finalize the takeoff
list. In completing the cap (item 1) note
that 10 pieces, 4'­0" long are required. Choos­
ing an 8­foot standard length and converting
to inches proceed as follows:
8'­0" = 8 x 12 = 96 inches
4'­0" = 4 x 12 = 48 inches
Then: 96
­­­ = 2 pieces with no waste.
48 Since this is the most economical selection
we can make, column 6 will read 8'­0" and
column 7 will read 2.
Developing column 8, divide the number
of pieces listed in column 3 by the pieces per
standard length listed in column 7. This
gives:
10
­­­ = 5 standard lengths.
2
Thus, the completed takeoff for item 1
would be:
_____________________________________________________________________________
(7)
(1) (2) (3) (5) (6) Number of (8)
Item Part Number Length Standard pieces per Number of
of pieces in place length standard standard
length lengths _____________________________________________________________________________
1 Cap 10 4'­0" 8'­0" 2 5
_____________________________________________________________________________ 5­15
Note: In this example column 4 is omitted
since it is not used in the calculations.
For the short collar (item 2) we need 4
pieces 1'­6" long. Again using an 8­foot stan­
dard length and proceeding as above:
8'­0" = 96 inches
1'­6" = 12 + 6 = 18 inches
Then:
96 ­­­ = 5 pieces with 6 inches of waste. 18 Since only 4 pieces are needed we will have
1 extra piece 18 inches long, plus 5 inches
of waste, giving a total waste of 23 inches.
But since the shortest standard length is 8
feet, this is the most economical.
Column 8 is developed as above:
4 pieces required
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­ =
5 pieces/standard length
0.8 standard length
Note: For any part of a standard length,
a full standard length must be used.
_____________________________________________________________________________
(7)
(1) (2) (3) (5) (6) Number of (8)
Item Part Number Length Standard pieces per Number of
of pieces in place length standard standard
length lengths _____________________________________________________________________________
2 Collar (short) 4 1'­6" 8'­0" 5 1
_____________________________________________________________________________
Note: Although only 4 pieces are required,
column 7 reads 5 pieces since this is
the number obtainable.
For the long collar (item 3) 4 pieces, 4'­4"
long are required. Trying an 8­foot standard
length:
8'­0" = 96 inches
4'­4" (4 x 12) + 4 = 48 + 4 = 52 inches
Then:
96 ­­­ = 1 piece with a waste of 44 inches
52
Next try a 10­foot standard length:
10'­0" = (10 x 12) = 120 inches
4'­4" = 52 inches
Then:
120
­­­ = 2 pieces with a waste of 16 inches
52 Following the same procedure for the 12­,
14­, 16­, 18­ and 20­foot standard lengths we
obtain:
12­foot­­2 pieces, 40 inches of waste
14­foot­­3 pieces, 12 inches of waste
16­foot­­3 pieces, 36 inches of waste
18­foot­­4 pieces, 8 inches of waste
20­foot­­4 pieces, 32 inches of waste
It should be evident that using an 18­foot
standard length is the most economical.
Column 8 for the long collar is computed
to be:
4
­ = 1 standard length
4 This item when completed should read:
_____________________________________________________________________________
(7)
(1) (2) (3) (5) (6) Number of (8)
Item Part Number Length Standard pieces per Number of
of pieces in place length standard standard
length lengths _____________________________________________________________________________
3 Collar (long) 4 4'­4" 18'­0" 4 1
_____________________________________________________________________________
5­16
Note: If 18­foot standard lengths are not
available, 10­foot lengths would be
used instead of 14­foot lengths. Two
10­foot lengths are needed to give
the 4 pieces required, with a total
waste of 32 inches. Two lengths are
also required for the 14­foot length.
Although there is only 12 inches
wasted from the first length, only one
more piece 4'­4" long is needed. This
gives a total waste of 12 inches +
116 inches, or 128 inches of waste.
Proceeding in the same manner for item 4
(stringer) the completed tabulation is:
______________________________________________________________________________
(7)
(1) (2) (3) (5) (6) Number of (8)
Item Part Number Length Standard pieces per Number of
of pieces in place length standard standard
length lengths ______________________________________________________________________________
4 Stringer 2 12'­0" 12'­0" 1 2
______________________________________________________________________________
Item 5 (Scabbing) is similar to item 2
(short collar). The only difference is the
number of pieces required. This item can be
developed exactly like item 2. A waste of 59
inches is obtained (only 2 pieces are re­
quired).
Also, item 6 (sill) is similar to item 1
(cap). The only difference is the nomencla­
ture of the part. The completed tabulation for items 5 and
6 are:
______________________________________________________________________________
(7)
(1) (2) (3) (5) (6) Number of (8)
Item Part Number Length Standard pieces per Number of
of pieces in place length standard standard
length lengths ______________________________________________________________________________
5 Scabbing 2 1'­6" 8'­0" 5 1
6 Sill 10 4'­0" 8'­0" 2 5 ______________________________________________________________________________
The completed takeoff list for the timber box culvert is shown in table 1.
5­17
11. BILL OF MATERIALS
After the materials takeoff is tabulated,
the actual bill of materials is compiled.
The bill of materials is arranged in tabular
form with column headings to include item
number, item, unit, quantity, board feet, and
a brief description of the item and where it
is used.
The items are listed according to materials
(wood, metal, etc.). Within each group of
materials the items are listed according to
size, usually beginning with the largest piece.
Items of like size are consolidated.
Consolidation is the process of combining
into one listing all identical items, re­
gardless of nomenclature.
Items of the same size and standard
length are consolidated.
The unit of measurement of lumber is the
board foot. By definition a board foot is the
volume of a board 1 inch thick, 1 foot wide,
and 1 foot long. BF, bf, MBF, mbf are all
commonly employed abbreviations for board
foot. M in front of the abbreviation stands
for 1000 board feet. Thus, 4 MBF would
indicate 4000 board feet.
From the above definition the following
formula is derived:
thickness in inches x width in inches
x length in feet x number of lengths
BF = ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­ 12
Example 3: Determine the board feet of 5
pieces of 3" x 12" lumber, 8 feet long.
Solution: From the above formula:
3 x 12 x 8 x 5
BF = ­­­­­­­­­­­­­­­­­­­­­­
12 BF = 120 board feet
Estimated quantities are also incorporated
into the BOM. These are quantities known
to be necessary but which may not have been
placed on the drawings, such as nails, cement,
concrete­form lumber and tie wire, temporary
bracing or scaffold lumber, and so on. Table 2
can be used to determine the quantity of nails
needed per 1000 board feet of a particular
size of lumber (the symbol "d" is the com­
mon abbreviation of pennyweight).
Nails are listed on a bill of materials as
pounds of nails required.
Example 4: Determine the nails required for
2000 board feet (2 MBF) of 1 x 6 material.
Solution: From table 2, it is seen that 40
pounds of 8­penny nails are required for 1000
board feet of 1 x 6 material. Therefore, 80
pounds are needed for 2 MBF.
Example 5: Determine the quantity of nails
needed for the lumber of example 3.
Solution: Referring to table 2, note that 145
pounds of 60­penny nails are required for
every 1000 board feet of 3 x 12 lumber.
120 BF = 0.12 MBF
Multiplying 145 pounds per MBF by 0.12
MBF gives 17.4 pounds of 60­penny nails
needed. Rounded up to the nearest whole
pound gives 18 pounds of nails required.
For simple objects the amount of nails
needed can be obtained by a direct count.
5­18
Example 6: By a direct count you determine
that 760 20­penny nails are needed for the
completion of a project. Determine the num­
ber of pounds needed for this job.
Solution: Referring to table 2, note that
there are approximately 29 nails in a pound
of 20­penny nails. The number of pounds is
obtained by dividing the total number of
nails needed by the number of nails per
pound:
total number of nails
pounds needed = ­­­­­­­­­­­­­­­­­­­­­
nails per pound
760
= ­­­­ 29 = 26.21 pounds, say 27
pounds
The completed bill of materials lists all
the material needed for the project and is
used in the ordering of this material.
Example 7: You are required to draw up the
bill of materials for the timber box culvert
(fig. 16), using the materials takeoff compiled
in example problem 2 (table 1).
Solution: The first step in the finalization
of a bill of materials is consolidation. Re­
ferring to table 1, notice that the largest
size of lumber is 3 x 12 material, with a
standard length of 8'­0". Both the cap (item
1) and the sill (item 6) require this size
lumber and are therefore consolidated. Since
5 lengths are required for each item, a total
of 10 lengths are needed. The first listing in
the BOM would read.
______________________________________________________________________________
(1) (2) (3) (4) (5) (6)
Item No. Item Unit Quantity BF Description
______________________________________________________________________________
Lumber
1 3 x 12­­8 ft pcs 10 ­­ Caps and sills
______________________________________________________________________________
Notice that column 5 (board feet) is not filled in. It is normally easier to
compile all items
of the BOM first and then go back and determine the board feet.
The next size item is the 2 x 12 material. Since this is used for only one item
(stringers) there
is no consolidation. This entry is.
______________________________________________________________________________
(1) (2) (3) (4) (5) (6)
Item No. Item Unit Quantity BF Description
______________________________________________________________________________
2 2 X 12­­12 ft pcs 2 ­­ Stringers
______________________________________________________________________________
The last size material is 2 x 10 lumber. Notice, however, that both an 8­foot
(table 1, items
2 and 5) and an 18­foot (table 1, item 3) standard length are required;
therefore, two sep­
arate entries are required. Also note that there is 23 inches of waste for the
short collar
(item 2) and 59 inches of waste for the scabbing (item 5). This gives a total
of 82 inches
of waste. If a 2 x 10 x 10­foot standard length is now chosen the waste would
be only 12
inches. (4 pieces 18 inches long (short collar) and 2 pieces 18 inches long
(scabbing)
gives a total requirement of 108 inches. Since a 10­foot standard length is 120
inches, we
can get both items from one 10­foot length.) Therefore, in consolidating this
item, change
the original choice of two 8­foot standard lengths to one 10­foot standard
length. We
can consolidate and use only one standard length for both items. The final
entries would be:
5­19
______________________________________________________________________________
(1) (2) (3) (4) (5) (6)
Item No. Item Unit Quantity BF Description
______________________________________________________________________________
3 2 x 10­­18 ft pcs 1 ­­ Long collars
4 2 x 10­­10 ft pcs 1 ­­ Short collars, scabbing
______________________________________________________________________________
Now we can complete the lumber portion of our BOM by determining the board
feet of
each item:
thickness (in) x width (in) x length (ft) x number of lengths
BF = ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­ 12
3 x 12 x 8 x 10 2880
Item 1: BF = ­­­­­­­­­­­­­­­ = ­­­­ 12 12 = 240 board feet 2 x 12 x 12 x 2 576 Item 2: BF = ­­­­­­­­­­­­­­­ = ­­­­
12 12
= 48 board feet
2 x 10 x 18 x 1 360
Item 3: BF = ­­­­­­­­­­­­­­­ = ­­­
12 12
= 30 board feet
2 x 10 x 10 x 1 200
Item 4: BF = ­­­­­­­­­­­­­­­ = ­­­
12 12
= 16.67 board feet
The completed BOM for the lumber requirement is:
_____________________________________________________________________________
(1) (2) (3) (4) (5) (6)
Item No. Item Unit Quantity BF Description
_______________________________________________________________________________
Lumber
1 3 x 12­­8 ft pcs 10 240 Caps and sills
2 2 x 12­­12 ft pcs 2 48 Stringers
3 2 x 10­­18 ft pcs 1 30 Long collars
4 2 x 10­­10 ft pcs 1 16.67 Short collars, scabbing
_______________________________________________________________________________
To complete the bill of materials, we now have to determine the amount of
nails needed.
Referring to table 2, it is seen that 145 pounds of 60­penny nails are needed
for 1000 board
feet of 3 x 12 lumber. Also, 52 pounds of 20­penny nails are needed for 1000
BF of 2 x 12
and 60 pounds of 20­penny nails are needed for 1000 BF of 2 x 10 lumber.
Then:
For item 1: 145 x 0.24 MBF = 34.8 pounds of 60d nails
For item 2: 52 x 0.048 = 2.49 pounds of 20d nails
Since items 3 and 4 are the same nominal size lumber, the board feet are
combined. There­
fore, for items 3 and 4: Total BF needed = 30 + 16.67 = 46.67.
5­20
Then, 60 x 0.047 = 2.82 pounds of 20d nails.
Notice that items 2, 3, and 4 all require 20­penny nails. The totals are
consolidated just
as the same sizes of lumber are consolidated. Therefore, 2.49 + 2.82 = 5.31
pounds of 20d
nails. Round up to 6 pounds.
The final bill of materials for the timber box culvert is shown in table 3.
12. ANSWERS TO SAMPLE EXERCISES
1. Visible lines or outlines 10. L
2. Dimension lines 11. 1 1/2"
3. Extension lines 12. 2"
4. P and S 13. 3"
5. K, L, J, and X 14. 1"
6. H 15. 1/2"
7. D 16. 1"
8. M 17. 3"
9. G 18. 2"
EXERCISES
First requirement. Solve multiple­choice
exercises 1 through 3 to show that you under­
stand the types of drawings and line conven­
tions used in construction.
1. Military drawings are either
construction or production drawings.
What constitutes a production draw­
ing?
a. parts suitable for production in
quantity
b. parts necessary for the construction
of a structure
5­21
c. drawings for production of a utili­
ties system
d. tools needed to produce the finished
structure
2. You are viewing a construction
drawing and have found a medium
weight line of evenly spaced short
dashes. Lines are symbols used on
drawings to show information necess­
sary for construction. What does this
line mean?
a. stitching
b. center of a circle
c. alternate position of a part
d. edge not visible in that view
3. A break line is used to save
space on a drawing. You have found a
break line used on the drawing you are
reviewing. How would you determine
the length of the object on which the
break line is used?
a. specified dimension
b. use of graphic scale
c. from different views
d. from drawing notes
Second requirement. Multiple­choice exer­
cises 4 through 7 enable you to demonstrate
your ability to understand construction draw­
ings and provide a chance to show your
knowledge of drawing interpretation.
4. In learning to read a construc­ tion print, you must develop the ability
to visualize the object. This is nothing
more than getting a three­dimensional
picture of the object from the different
views shown on the print. What is this
three­dimensional drawing of an object
called?
a. perspective c. orthographic
b. isometric d. box
5. A three­dimensional drawing of
a concrete abutment is shown in view
"X", figure 17. Which of the other four
views also shown is the correct front
view for this abutment?
a. A c. C
b. B d. D
6. Sectional views are formed by
cutting an object with an imaginary
plane, removing the portion of the ob­
ject in front of the plane, and viewing
that portion behind the plane (see fig.
11). What is the primary purpose of
a section view?
a. determine dimensions
b. show the material of the object
c. explain the primary notes of the
drawing
d. show details which cannot other­
wise be shown
7. Dimensions are placed on a
drawing to give additional information
and to aid the construction worker.
Which of the following dimensions is a
location dimension?
a. groove depth
b. overall width of object
c. diameter of a circle
d. distance of a circle from an edge
Third requirement. Multiple­choice exer­
cises 8 and 9 are designed primarily to point
out the additional information that can be
obtained from prints. 8. The title block on a drawing
provides useful information to the con­
struction worker. Which of the follow­
ing would be included in the title block?
a. notes
b. specifications
c. sheet number
d. revision block
5­22
5­23
9. Your squad is required to con­
struct a concrete abutment similar to
that shown in figure 17. Where would
you find information concerning the ul­
timate compressive strength of this
concrete?
a. notes
b. specifications
c. sectional view
d. bill of materials
Fourth requirement. Multiple­choice exer­
cises 10 through 14 provide you with an op­
portunity to display your knowledge of a
materials takeoff tabulation.
General situation. Your battalion has been
given a directive to construct a road for
supply purposes. The battalion S­3 assigned
your company to construct three bridges for
this road. Your squad is to construct a timber
trestle bent from the print shown in figure 18.
Your squad leader gives you a materials take­
off for this bent and tells you to go to S­4
for the necessary supplies. Below is the take­
off list (table 4) that your squad leader has
tabulated. Questions 10 through 13 pertain
to this takeoff.
10. The first step in a materials
takeoff tabulation is to list all the parts
of a structure. What part (col 2)
should be listed for item 4 (col 1)?
a. sill b. stringer
c. short collar
d. longitudinal bracing
11. You notice that you need 7 foot­
ings (item 3, col 1). What size (col 4)
lumber (in inches) is required for this
item?
a. 2 x 6 c. 3 x 12
b. 2 x 10 d. 6 x 6
12. You realize that in order to de­
termine the number of standard lengths
(col 8) for an item you must know the
length in place (col 5) and the number
of pieces per standard length. How
many pieces per standard length (col 7)
can be obtained from the standard
length (col 6) shown for the scabbing
(item 5, col 1)?
a. 18 c. 20
b. 19 d. 21
13. The number of standard lengths
is not necessarily the same as the num­
ber of pieces of an item, since more
than one piece can generally be cut from
one board. What entry should be made
5­24
for the number of standard lengths
(col 8) for the footings (item 3, col 1)
if the standard length (col 6) shown is
used?
a. 1 e. 5
b. 3 d. 7
14. For economical reasons, the
standard length used for a particular
item should be selected so as to produce
the least amount of waste. What stan­
dard length (in feet) is the most eco­
nomical for 8 pieces of 2 x 4 lumber
6'­3" long?
a. 8 c. 16
b. 14 d. 20
Fifth requirement. Multiple­choice exer­
cises 15 through 20 finish your instruction in
construction planning by enabling you to
show your ability in reading and completing
bills of materials.
General situation continued. You finally
take the completed materials takeoff to the
battalion supply officer who informs you that
requisitions are made from a bill of ma­
terials and that the materials takeoff is a
preliminary step in the preparation of a bill
of materials. Below is the bill of materials
(table 5) partially completed for the timber
trestle bent shown in figure 18. Exercises 15
through 19 pertain to this BOM.
15. The bill of materials provides
all necessary information for the requi­
sitioning of supplies. What quantity
(col 4) should be entered for item 1?
a. 1 c. 3
b. 2 d. 4
16. Item listings for lumber show
the size and length of material required
for a particular part. What entry should
be made in column 2 (item) for item
number 2?
5­25
a. 3 x 12 ­ 8 ft
b. 3 x 12 ­ 12 ft
c. 6 x 6 ­ 8 ft
d. 6 x 6 ­ 12 ft
17. The description shows where
each particular item is to be used.
What should be entered under the de­
scription (col 6) for item number 4?
a. scabbing
b. stringer
c. transverse bracing
d. longitudinal bracing
18. The board foot is used as the
measure of lumber, and the cost of
lumber is based upon it. What do you determine the board feet (col 5) of item 4 to be? a. 20 c. 240
b. 80 d. 960
19. You are told that the nail re­
quirements are to be determined by
direct count. Your platoon sergeant
also told you that 7 20­penny nails are
required for each piece of scabbing and
20 20­penny nails are required for each
transverse brace. What is the 20­penny
nail requirement (in pounds) for the
timber trestle bent shown in figure 18?
a. 2 c. 8
b. 5 d. 11
20. For a different project you are
told that 2300 board feet of 3 x 12
lumber is required. What quantity of
60­penny nails (in lb­­round up to
nearest 10­lb) is needed for this job?
a. 230 c. 300
b. 270 d. 340
5­26
LESSON 6
CREDIT HOURS ______________________
TEXT ASSIGNMENT ___________________Attached Memorandum.
MATERIALS REQUIRED ________________None.
LESSON OBJECTIVE __________________To teach soil characteristics and how they
may be improved for construction pur­
poses.
______________________________________________________________________________
ATTACHED MEMORANDUM 1. SOIL DEFINED
The term soil is applied to the rock particles
produced by the mechanical and chemical
breakup of rocks. In most soils these rock
particles are mineral grains which are not
cemented together. The voids or spaces be­
tween the grains may or may not contain
water. In addition, some soils contain organic
matter, shells, or other material in various
forms and quantities.
2. UNIFIED SOIL CLASSIFICATION SYSTEM
The Unified Soil Classification System is a
means of determining those soil character­
istics which indicate a soil's behavior as a
construction material. In this system a soil
can be put into one of several soil categories.
The suitability of each soil category for engi­
neering work has been determined by experi­
ence so that a reliable estimate of the ex­
pected behavior of the soil in question can be
made.
Principal soil categories as defined by the
Unified Soil Classification System are: coarse­
grained soils, which consist of gravel and
sand; fine­grained soils, which consist of silt
and clay; and organic soils, which are any
soils, regardless of grain size, containing a
considerable amount of organic (decayed or
decaying vegetation) material.
3. GRAVEL
Gravel is a mass of rock particles, generally
waterworn, which pass a 3­inch sieve and are
retained on a no. 4 sieve (0.187 inch).
Next to solid bedrock, well­graded and com­
pacted gravel is the most stable natural foun­
dation material. It is classified as coarse or
fine; well­ or poorly­graded; angular, flat, or
rounded. It is desirable material for both
bases and subgrades if well­graded. When
used for road surfaces, sufficient fine­grained
material must be included to bind the larger
individual particles in place.
Gravel is easy to drain, easy to compact
when well­graded, little affected by moisture,
and not affected by frost action.
Deposits of gravel commonly contain a
considerable percentage of sand and even silt
or clay.
4. SAND
Granular material composed of rock par­
ticles which pass a no. 4 sieve and are retained
on a no. 200 sieve (.0029 inch) is called sand.
It is difficult to distinguish sand from silt
when the sand particles are small and uniform
in size. Dried sand, however, differs from
silt in that it has no cohesion and feels more
gritty.
6­1
Sand is classified as coarse, medium, or
fine; well­ or poorly­graded; angular or
rounded.
Well­graded and compacted sand is desir­
able for concrete aggregate and for founda­
tion material. It is easy to drain, little af­
fected by moisture, and ordinarily not af­
fected by frost action.
5. SILT
Silt is a fine, granular material composed
of particles which pass the no. 200 sieve.
Silt lacks plasticity (plastic soil is general­
ly soft and can be molded) and has little
strength when dry.
To identify silt, prepare a pat of wet soil
and shake it horizontally in the palm of the
hand. If the soil is silt, the shaking action
will cause water to come to the surface of
the sample, making it appear glossy and soft.
Squeezing the wet sample between the fingers
causes the water to disappear from the sur­
face and the sample quickly stiffens and
finally cracks or crumbles.
Allow the sample to dry thoroughly and
test its cohesion and feel by crumbling with
the fingers. Typical dry silt shows no strength
and feels only slightly gritty in contrast to
the rough grittiness of fine sand.
All types of silt are treacherous. Because
of their inherent instability, slight distur­
bances in the presence of water, such as
traffic vibrations transmitted to a wet silt
subgrade, may cause them to become soft
or to change into a "quick" (by "quick" is
meant easily moved or shifted) condition.
When ground water or seepage is present,
silts exposed to frost action are subject to
severe ice accumulation and consequent heav­
ing.
Silts are difficult to compact and drain.
6. CLAY Clay is also fine­grained material composed
of particles which pass the no. 200 sieve.
To identify clay, work a sample with the
fingers, adding water when the stiffness re­
quires it. The moist sample is workable
enough to be kneaded like dough.
Make a further test by rolling a ball of
kneaded soil between palm of hand and a
flat surface. Clay can be rolled to a slender
thread, about 1/8­inch in diameter, without
crumbling; fine silt, which resembles clay,
crumbles without forming a thread.
Measure the hardness of the sample by the
finger pressure required to break it. Much
greater force is required to break dry clay
than dry silt.
Clay feels smooth in contrast to the slight
grittiness of silt.
The character of undisturbed clay, especial­
ly its hardness, is quite different in the na­
tural state than that of a sample removed
for testing. As found in undisturbed natural
conditions, clay may be hard, medium, soft,
or extremely soft, depending upon the natural
moisture content and density. Hard clay
that cannot be remolded with ordinary finger
pressure requires a pick for excavating. Soft
clay that can be easily remolded by hand can
be readily excavated with a shovel.
Low resistance to deformation when wet,
imperviousness to water, especially when wet,
and large expansions and contractions with
changing moisture content are typical of
clays.
Wet clays are impossible to compact.
Clays absorb surface water or ground seep­
age slowly and retain it well, making it im­
possible for additional surface water to be
absorbed or to drain downward through the
already saturated soil.
Too much clay in a base course is harmful
and must be avoided whenever large changes
in moisture content may be expected.
Example 1: A sieve analysis yields the fol­
lowing data: 60 percent retained on no. 4
sieve, 30 percent passing no. 4 but retained on
no. 200 sieve. No organic material is present.
What classification would you assign to this
soil?
6­2
Solution: Since most of the material is re­
tained on no. 4 sieve, the soil is primarily a
gravel, and may be classified as such. In
addition, the soil contains some sand (the 30
percent passing no. 4 but retained on no. 200)
and fine material (90 percent is retained on
no. 200, so 10 percent must be fine material).
7. ORGANIC SOIL
Soil which is primarily composed of de­
cayed or decaying vegetation is termed or­
ganic soil. Fine­grained mineral sediments
may also be found in this soil.
Organic soil is identified by a coarse and
fibrous appearance and an odor. The odor
may become more noticeable when the soil
is heated.
Another aid in identifying organic soil is
that a sample can be rolled into a soft, spongy
thread.
Organic soils are unsatisfactory subgrade
materials because of their low strength and
low resistance to deformation. The Corps of
Engineers requires complete removal of all
organic materials.
8. GRADATION
Soils may be divided into several different
types on the basis of grain size. The propor­
tion of various grain sizes in a soil sample
determines its gradation, or grain­size dis­
tribution.
A soil may be termed either well­graded or
poorly­graded, depending on the distribution
of grain sizes in the soil.
A soil having a good representation of all
particle sizes is defined as a well­graded soil.
A diagram of a well­graded soil is shown in
figure 1 1 .
Any soil not meeting the requirements of
a well­graded soil is termed a poorly­graded
soil. There are two types of poorly­graded
soils, uniformly­graded and gap­graded.
A uniformly­graded soil consists mostly
of particles nearly uniform in size.
A gap­graded soil contains some large
and some small particles but the con­
tinuity of gradation is broken by the
absence of some sizes of particles.
Uniformly­graded soils and gap­graded
soils are shown in figures 1 2 and 1 3 . Determination of gradation. The gradation
or grain­size distribution of a soil is de­
termined by mechanical analysis. The meth­
ods of mechanical analysis in use are sieve
analysis, wet mechanical analysis (sedimen­
tation), and a combination of these two
methods.
Sieve analysis. A sieve analysis is sufficient
to classify most materials, especially those
with little or no fines (very small particles).
The test procedure for a sieve analysis is
as follows:
Oven dry the soil sample.
Weigh the sample.
Transfer the soil sample to a set of sieves
and shake the stack vigorously for 5­15
minutes.
Record the weight of the material re­
tained on each sieve.
Compute the percentage of material
passing each sieve.
6­3
The percentages obtained indicate the
gradation of the soil sample.
Wet mechanical analysis. Wet mechanical
analysis is suited primarily for fine material,
although it may be applied to coarse­grained
material as well. Particle size is determined
by the rate of settling in water.
Combined method of analysis. A combina­
tion of the two methods is required to com­
pletely determine grain­size distribution of
a soil with a wide range of grain size. This
degree of thoroughness is not normally necess­
sary in routine tests, however.
Effect of gradation on bearing capacity.
Coarse materials that are well­graded are
usually preferable for supporting a load be­
cause good gradation usually means the soil
can be compacted to high density and con­
sequent stability.
Specifications controlling the percentages
of coarse­ and fine­grained materials needed
to make up a well­graded soil make it possible
to provide for maximum density. Such pro­
portioning develops a sort of interlocking of
particles with smaller particles filling the
spaces between larger particles. This makes
the soil stronger and more capable of sup­
porting heavy loads.
9. PARTICLE SHAPE
The shape of individual particles has an
effect on the suitability of a soil as an engi­
neering material.
The rough, angular shape particles such
as are produced by a rock crusher are gen­
erally the best shaped particles for construc­
tion purposes, especially when well­graded.
The rounded type particles, such as river
run gravel, are usually satisfactory for any
theater of operations work if well­graded.
Uniformly­graded round particles, however,
can cause stability problems.
10. FIELD IDENTIFICATION
Classification of soils in the field must often
be made without laboratory equipment. Soil
properties must be estimated and tentative
classifications assigned. Such a procedure is
called field identification.
Principal tests are the shaking test, the
roll or thread test, the ribbon test, the break­
ing or dry strength test, and the odor test.
Shaking test. In this test a wet pat of
soil is alternately shaken horizontally and
squeezed between the fingers. The soil is said
to have given a reaction to this test when,
on shaking, water comes to the surface giving
a wet, shiny appearance. When the sample
is then squeezed, the surface water quickly
disappears, leaving the surface dry and dull
in appearance. A rapid reaction of this type
is typical of silts and fine sands that contain
little or no clay. A slow reaction or no re­
action at all will result if organic material
or clay is present in moderate to large
amounts.
Roll or thread test. This test is performed
only on material passing the no. 40 sieve. A
moist soil sample is repeatedly rolled into a
thin thread (about 1/8­inch in diameter) until
it breaks or crumbles. A sample which quick­
ly breaks or crumbles is predominately fine
sand or silt. A sample which shows little or
no tendency to crumble contains considerable
clay.
Ribbon test. Only material passing the no.
40 sieve is used in the test. A roll of moist
soil is flattened into a ribbon 1/8 to 1/4 inch
thick. The maximum length of ribbon which
can hold together when the ribbon is sup­
ported only at one end indicates the amount
of clay present in the sample. If the soil
sample holds together for a length of 8 to
10 inches without breaking, the material is
then considered to have a high clay content.
If it cannot be ribboned, or can be ribboned
only into short lengths, then the sample is
fine sand or silt with little or no clay content.
Breaking or dry strength test. Use only
material passing the no. 40 sieve. A wet pat
of soil about 1 1/2 inch in diameter and 1/2 inch
thick is allowed to air dry and is then broken
with the thumb and forefingers of both hands.
Samples which cannot be broken are primari­
ly clay. Samples with little or no clay break
and crumble easily.
6­4
Odor test. Organic soils usually have a dis­
tinctive, musty, slightly offensive odor which,
with experience, can be used as an aid in
identification. This odor is especially appar­
ent in fresh samples. It is gradually reduced
when exposed to air, but can be brought out
again by heating a wet sample.
11. SOIL STRENGTH
Soil strength is a measure of the ability
of a soil used as a base or subgrade beneath
a road or airfield to support a load.
Soil strength is measured by the California
Bearing Ratio (CBR) test, the field plate
bearing test, and the airfield cone penetrom­
eter.
The CBR test is a widely used method
which measures the strength of soil samples
removed from the subgrade at various loca­
tions. Special equipment and trained per­
sonnel are required.
The field plate bearing test is an expensive
and time­consuming method which requires
good judgment in interpretation of results.
The strength of the subgrade soil in place is
measured by this test.
The airfield cone penetrometer gives a mea­
sure of in­place soil strength called the air­
field index. It is a simple technique which
may be used by inexperienced personnel.
The penetrometer consists of a 30­degree
cone of 1/2­square inch base area, an
aluminum staff 19 inches long and 5/8
inch in diameter, a proving ring, a mi­
crometer dial, and a handle. When the
cone is forced into the ground, the prov­
ing ring is deformed in proportion to the
force applied. The amount of force re­
quired to move the cone into the ground
is indicated in the dial inside the ring.
Readings are normally taken at 6­inch
intervals as the cone moves downward.
12. SETTLEMENT
Settlement of a highway or airfield may
result from a consolidation of underlying soil.
By consolidation is meant the reduction in
volume of a layer of soil due to the weight
of overlying soil.
Settlement is generally most severe in clays
and loose sands.
Dense sands and gravels usually change
very little in volume after completion of con­
struction and are therefore very good foun­
dation materials. 13. COMPACTION
By compaction is meant the process of
mechanically densifying a soil. Compaction
implies the application of moving loads (com­
paction equipment) to the soil mass. This is
in contrast to the consolidation process in
which a soil mass becomes more dense as
the result of the application of a static load
(weight of the overlying soil).
The density obtained by compaction is
normally expressed in terms of dry density
(weight of solids per cubic foot) expressed
in pounds per cubic foot.
Advantages gained from compaction. Prin­
cipal soil properties which are affected by
compaction include settlement, soil strength,
movement of water, and volume change.
One of the principal advantages which re­
sult from the compaction of soils used in
embankments is that it reduces to a minimum
the settlement which might occur as the re­
sult of consolidation of the soil within the
body of the embankment.
Increasing the density by compaction will
prevent later consolidation within the em­
bankment, but it must be remembered that
the embankment might still settle as a result
of consolidation of the soil on which the em­
bankment rests.
Increasing density by compaction usually
increases soil strength. This permits use of
a thinner pavement and steeper embankment
side slopes than would otherwise be possible.
When soil is compacted, the amount of
voids in the soil is decreased. This reduces
the permeability (ease with which water
moves through the soil) which reduces seep­
6­5
age. The movement of capillary water is
also minimized, reducing the tendency for
the soil to take up water and suffer later
reductions in strength.
Volume change in relation to compaction
is generally not a matter of concern, except
for clay soils. Clays are subject to large
volume changes as they go from wet to dry
(or vice versa) unless restrained, but gen­
erally may be compacted so that volume
change is a minimum.
14. COMPACTION EQUIPMENT
To achieve the desired properties listed in
paragraph 13, care must be used in selecting
types of compaction equipment to be used on
a given material.
Generally, steel­wheeled rollers are recom­
mended for angular materials with limited
amounts of fines; crawler­type tractors or
rubber­tired rollers for gravel and sand; and
sheeps­foot rollers for coarse­grained or fine­
grained soils having appreciable amounts of
cohesive materials.
Rubber­tired rollers are recommended for
final compaction operations.
15. CONCLUSION
The best materials for construction are the
coarse­grained soils of the Unified Soil Classi­
fication System (sand and gravel). They
should be well­graded and free of organic
material.
The fine­grained soils are less desirable,
being more difficult to compact and requiring
more careful control of construction methods.
Compaction is used to improve soils which
would not be suitable for construction work
in their natural states. Improvements which
result from properly controlled compaction
are minimization of settlement, increase in
soil strength, reduced permeability to water,
and reduced volume changes caused by chang­
ing moisture content.
EXERCISES
First requirement. Multiple­choice exer­
cises 1 and 2 deal with the definition of soil
and basic size groupings.
1. Soil is composed of several ma­
terials. Which of the following ma­
terials is the primary component of
soil?
a. organic material
b. water
c. rock particles
d. air
2. You are examining a soil which
is primarily composed of fine­grained
material. Which of the following groups
could this soil fall into?
a. sand and gravel
b. sand and clay
c. silt and clay
d. sand and silt
Second requirement. Multiple­choice exer­
cises 3 through 11 are designed to enable
you to demonstrate your knowledge of soil
characteristics and identification of soils.
3. Given the following sieve an­
alysis: 30 percent retained on no. 4
sieve, 55 percent passing no. 4 but re­
tained on no. 200 sieve, and 15 percent
passing no. 200 sieve. No organic mat­
ter is present. How would you classify
this soil?
a. coarse­grained
b. fine­grained
6­6
c. organic
d. cannot be classified
4. Your sieve analysis yields the
following results: 7 percent retained
on no. 4 sieve and 83 percent passing
no. 4 but retained on no. 200 sieve. No
organic material is present. What classi­
fication would you assign to this soil?
a. a sand containing some fine­grained
material
b. a sand with no fine­grained ma­
terial
c. a silty gravel
d. clay
5. You are to use a silty soil for
subgrade construction. Which of the
following statements best describes this
soil?
a. it is easy to compact and drain
b. it is little affected by water
c. it is preferable to sand for this pur­
pose
d. it is composed of material passing
no. 200 sieve
6. Silt may easily be mistaken for
fine sand by an untrained observer. How
is silt most easily distinguished from
fine sand in the field?
a. silt has an odor, especially when
heated
b. silt has a very rough, gritty feel
compared to the smoothness of fine
sand
c. silt has only a slightly gritty feel
compared to the rough grittiness of
fine sand
d. silt cannot be distinguished from
fine sand in the field
7. You are trying to determine
whether the fine­grained material at
your construction site is silt or clay.
How is clay most easily distinguished
from silt in the field?
a. silt has an odor, especially when
heated
b. clay feels smooth in contrast to the
slight grittiness of silt
c. clay feels slightly gritty in contrast
to the smoothness of silt
d. clay has a distinguishing yellow
color
8. Which of the following soils is
most nearly impervious to water?
a. wet clay
b. dry sand
c. dry silt
d. uniformly­graded gravel
9. Certain soils drain well in their
natural state. To minimize drainage
construction, which soil would you rec­
ommend using?
a. any impervious soil
b. clay
c. silt
d. gravel
10. How would you most easily
identify organic soil in the field?
a. gradation c. density
b. particle shape d. odor
11. Given the same sieve analysis
as in exercise 3, except that the soil
consists primarily of organic matter,
how would you classify this soil?
a. coarse­grained
b. fine­grained
c. organic
d. cannot be classified
6­7
Third requirement. Solve multiple­choice
exercises 12 through 15 to test your under­
standing of the requirements for soils to be
used in construction.
12. You are to build a subgrade for
a road on which heavy vehicles will travel. Which of the following soils is most suitable for this purpose?
a. a uniformly­graded soil
b. a well­graded soil
c. a gap­graded soil
d. a poorly­graded soil
13. When selecting a construction
material, you must remember that par­
ticle shape can affect stability. Which
of the following soils would generally
be most desirable for construction pur­
poses?
a. well­graded, rough angular gravel
b. uniformly­graded, rough, angular
gravel
c. well­graded, rounded gravel
d. uniformly­graded, rounded gravel
14. Certain soils have unfavorable
settling characteristics. Settlement is
generally most severe in which of the
following materials?
a. clays and loose sands
b. loose gravel
c. compacted gravel
d. compacted sand
15. A soil is to be selected for an
airfield base course. What type of soil
should you select?
a. a soil which changes little in volume
after construction
b. a soil with primarily uniformly­
graded material
c. a soil with primarily gap­graded
material
d. a soil which has little dry strength
Fourth requirement. Work exercises 16
through 20 to demonstrate your understand­
ing of compaction.
16. Compaction is the process of
mechanically densifying a soil by what
means?
a. application of static load
b. application of moving loads
c. use of a cone penetrometer
d. use of consolidation techniques
17. At a proposed road site you ob­
serve that the topsoil is a well­graded,
loose sand. What recommendation
would you make concerning economical
construction at this site?
a. excavate until bedrock is reached
b. construction here is impractical
c. compact the loose sand
d. lay pavement over the loose sand
to minimize settlement
18. Your unit has built an embank­
ment over a soft clay soil. The embank­
ment is of quality fill material and
properly compacted. An asphalt­sur­
faced roadway was then built over the
top of the embankment. What might
happen to the roadway concerning set­
tlement?
a. the roadway cannot settle because
the embankment is properly con­
structed
b. the roadway may settle because of
compression of the clay under the
embankment
c. the roadway will not settle because
it is well surfaced
d. the roadway may settle because of
consolidation within the embank­
ment
6­8
19. You are given the task of as­
signing compaction equipment to
various sections of a road under con­
struction. You can best utilize your
steel­wheeled rollers by assigning them
to what type of soil?
a. gravel such as that produced by a
rock crusher
b. river run gravel containing con­
siderable fines
c. any fine­grained soil
d. organic material
20. Your unit is completing com­
paction operations on a sandy soil which
contains a small amount of fine­grained
material. What equipment would you
recommend for the final compaction op­
erations?
a. sheepsfoot rollers
b. steel­wheeled others
c. crawler­type tractors
d. rubber­tired rollers
6­9
LESSON 7
ROADS AND CULVERTS
CREDIT HOURS ______________________2
TEXT ASSIGNMENT ___________________Attached memorandum.
MATERIALS REQUIRED ________________None. LESSON OBJECTIVE __________________To provide you with a working knowledge of
the construction of expedient roads and
cul­
verts.
______________________________________________________________________________ ATTACHED MEMORANDUM
Section I. EXPEDIENT ROAD MATERIALS AND SURFACES
1. INTRODUCTION
Expedient roads are usually constructed as an emergency measure for crossing
difficult
terrain. The two basic types of expedient roads are hasty and heavy.
2. HASTY ROADS
Hasty roads require the least time to construct. They are generally used to
cross a terrain
obstacle such as a beach or marsh. Often they will be constructed during
darkness, so they
must, of necessity, be simple and constructed of light, easily handled
materials.
Army track is a portable timber expedient used to pass vehicles over sand or
wet ground.
It can be constructed as shown in figure 1.
Chespaling mat roads are composed of mats 6 1/2 by 12 feet long. They are
made of small
saplings wired together to form the mat and are laid as shown in figure 2.
Bamboo mats (fig. 3) are sometimes used for expedient road surfaces. They
are especially
adaptable for beach roadways and for entrances and exits to fords. The mats
should be laid
with the long axis of the bamboo perpendicular to the direction of traffic.
Wire mesh expedients may be composed of chicken wire, chain­link fence, and
cyclone fence.
They are adaptable for use in sand with burlap or similar material underneath.
They require
a great deal of maintenance and are used only in emergencies.
3. HEAVY ROADS
Heavy roads are generally used because of special ground conditions or lack
of standard con­
struction materials. Standard road construction procedures which should be
followed whenever
possible are as follows:
Clear road location.
Install drainage facilities.
Grade the foundation, crowning it as necessary.
7­1
7­2
Lay the expedient material.
Construct one­way roads with turnouts or two­way roads with tracks side by
side.
Maintain the road.
Replace expedient roads with more durable roads as soon as possible.
Airfield landing mats are the most commonly used of heavy expedients. They
are laid as
shown in figure 4.
Plank roads (fig. 5) may be used where lumber is in plentiful supply.
Corduroy construction may be used over muddy terrain when sufficient natural
material is
available. There are three types of corduroy construction­­standard corduroy,
corduroy with
stringers, and heavy corduroy. The general rule to be followed is, the softer
the ground, the
heavier the corduroy to be constructed.
Standard corduroy (fig. 6) is the most common corduroy used. It is
constructed of 6­ to
8­inch logs laid adjacent to each other (butt to tip) across the roadway. Curb
logs are laid
along the ends and are drift­pinned or wired in place. To provide a smooth
surface, brush,
twigs, or rubble can be placed in the chinks and covered with dirt or ground
(fig. 7). Side
ditches and culverts should be constructed as for normal roads.
7­3
7­4
7­5
Corduroy with stringers (fig. 8) provides a more substantial road than
standard corduroy.
It is made by placing log stringers parallel to the centerline of the road on
about 3­foot centers.
Corduroy is then spiked or securely fastened to the stringers.
Heavy corduroy is constructed by the use of sleepers on about 4­foot centers
under the
stringers as shown in figure 9. The road is then constructed as for corduroy
with stringers.
Fascine corduroy, another type of heavy road, can be constructed for use in
swampy or
boggy ground where neither standing timber nor logs are available. They are
constructed
by bundling secondary growth, brush, or saplings and used as for standard
corduroy. De­
tails of construction are shown in figure 10.
Plank tread roads can be constructed easily and rapidly. They require less
material than
plank roads. Construction details are shown in figure 11.
7­6
4. PIONEER ROADS
The expedient roads which have been dis­
cussed are often constructed under circum­
stances which prevent the use of standard
methods of construction. Pioneer roads,
which are sometimes constructed and used
as expedients, are the simplest and least
7­7
7­8
expensive types of ordinary roads, but are
built by standard methods of construction.
They differ from higher type roads mainly
in the matter of location and are justifiable
by primitive conditions and low service re­
quirements. They should be located so that
they can be improved by stages rather than
be abandoned for another route.
Section II. CLEARING, GRUBBING, AND STRIPPING
5. LAND CLEARING
Land clearing is a construction operation
consisting of clearing a designated area of
all trees, brush, other vegetation, and rub­
bish; removing surface and embedded boul­
ders; and disposing of the material cleared.
Clearing operations may be accomplished
with pioneer tools, but normally it is most
rapidly and efficiently accomplished with
heavy engineer equipment. Excess materials
created in the clearing operation may be
disposed of by use of waste areas or by burn­
ing.
Felling equipment includes handtools,
power tools and heavy equipment. In hand
clearing, axes, two­man saws, pick mattocks,
machetes and brush hooks are used to clear
standing timber and brush. Portable chain­
saws, electric, pneumatic or gasoline­engine
powered, are items of issue. They are used
for felling larger trees and cutting logs into
shorter lengths which can be manhandled
to the disposal area or used for construction.
Heavy equipment used in land clearing
includes tracked tractors equipped with bull­
dozer or land clearing blades, winches, and
as expedients, motor graders and scrapers.
A tracked tractor equipped with a land clear­
ing blade is 30 to 40 percent more efficient
than a bulldozer blade in medium to large
trees. The land clearing blade cuts the trees
at ground level rather than uprooting them
as the bulldozer does. Heavy duty winches
can be used to uproot trees and stumps and
are especially effective in soft muddy soil where the tree is easily uprooted and the soil
is too soft to support a tractor. Motorized
graders and towed scrapers can be used in
land clearing but their application is limited
to clearing grass, weeds, and small brush
from the construction site.
The use of fire in clearing is an expedient
which will be used only when suitable equip­
ment and personnel are not available for other
methods. To minimize detection, fires are
not permitted at night unless tactical con­
ditions are favorable and approval has been
received from higher headquarters.
Explosives may be used to advantage in
felling trees and uprooting stumps. They are
most widely used for clearing where terrain
prevents the use of other methods.
6. GRUBBING
The use of heavy engineer equipment for
grubbing is standard where the terrain per­
mits. Explosives are often used to loosen
trees stumps: rooters cut shallow roots and
loosen boulders. Scrapers can be effectively
used to haul loosened stumps and boulders
to a disposal area. Power shovels or front
loaders may be used to load stumps and
boulders into dump trucks for disposal.
7. STRIPPING
The process of stripping consists of re­
moving and disposing of top soil, sod, and
other material not suitable as a subgrade,
as a foundation under a fill, or as borrow
material. Stripping is done concurrently with
clearing and grubbing by use of dozers,
scrapers, and power shovels. In an emer­
gency, it is done by hand.
8. SAFETY Careful consideration must be given to
safety of personnel during all clearing, grub­
bing, and stripping operations.
7­9
9. DISPOSAL AND SALVAGE
Disposal and waste areas should be desig­
nated at the start of construction in order to
keep the construction area clear for essential
operations. Timber useful for logs, piles, and
lumber is trimmed and stockpiled for future
use in bridges, culverts, and other types of
construction. This type of material can be
pushed or skidded into a salvage area for
later removal to a sawmill. Generally, the
material disposed of is pushed or skidded
off the construction site and into the sur­
rounding timber to speed disposal. The dis­
posal areas should be selected carefully so
that the debris is piled where it will not in­
terfere with the drainage of the construction
site. Section III. DRAINAGE
10. DRAINAGE FACILITIES
Drainage facilities which are properly
planned and constructed are essential to con­
tinuous serviceability of roads. The washout
or blockage of a single culvert may close a
road to traffic at a vital time. In the TO
surface ditching is used almost exclusively
for drainage.
Continuous emphasis must be placed on
construction drainage from the start of any
road project in order to prevent construction
delays due to ponding of water and sub­
sequent subgrade failure. During clearing
and grubbing operations, drainage channels
must be kept clear and holes and depressions
filled and compacted to grade.
Rough crown and grade must be main­
tained to permit rain water, runoff water, and
spring water to move from the construction
site.
One of the first steps in construction op­
erations is to provide drainage from the con­
struction site.
Diversion and outfall ditches are used to
concentrate surface water into natural chan­
nels.
Existing ditches and drainage features are
used to the maximum to reduce the work­
load.
If the road is to be used for only 1 to 2
weeks, detailed drainage design is not justi­
fied. If improvement or expansion is antici­
pated, great care must be given to design.
Drainage problems are greater when all­
weather operation is required than when in­
termittent use is expected.
The two basic types of drainage are surface
and subsurface.
Surface drainage (fig. 12) provides for the
collection and removal of water from the
surface of roads as well as underdeveloped
areas. It also provides for the interception,
collection, and removal of surface water flow­
ing toward roads from adjacent areas.
Subsurface drainage is designed to inter­
cept, collect, and carry ground water away
from the base course or subgrade; to lower
high water tables; to drain water from
pockets or perched water tables; or for a
combination of these.
Ditches collect and channel surface runoff
and carry it to a convenient disposal area.
The two most common types are the V­type
and the trapezoidal.
The V­type ditch is the most common type
used due to ease of construction and main­
tenance. A motorized or towed grader is the
ideal piece of equipment for use in construc­
ting these ditches. Where the depth of a
ditch is fixed and the volume of water is
great a trapezoidal ditch of varying width
can be used. Graders or towed scrapers with
experienced operators can be used to con­
struct these ditches. The shape of the trape­
zoidal ditch more readily lends itself to use
in sandy or easily erodable soil as excess flow
7­10
will cut into the sides and fill in the bottom
of "V" ditches. Figure 13 depicts the recom­
mended shapes, side slope ratios, and sizes
of ditches for use in TO construction.
11. FUNCTIONS OF DITCHES
Longitudinal side ditches (fig. 12) collect
the surface runoff and carry it alongside the
road to a disposal area.
Where a relatively large area outside the
limits of a construction project drains toward
the project, interceptor ditches (fig. 12) may
be constructed to prevent water from reach­
ing and eroding cut and fill slopes. They are
also used to prevent direct flooding of op­
erational areas.
Wherever possible, diversion or relief
ditches should be constructed to move water
from collecting channels or ditches into na­
tural drains to be carried away from the con­
struction site.
12. EROSION CONTROL IN DITCHES
When the slope of a ditch is too great it
tends to increase the speed of the water,
thus eroding the walls or bottom of the ditch.
7­11
The minimum slope for side ditches is set
at 0.5% and the maximum desirable slope is
4%. When the ditch slope is between 3% and
5%, checkdams are normally constructed to
reduce the speed of the water. Checkdams
may be constructed of timber, sandbags, con­
crete, rock, or similar materials. Height of
the checkdam should be at least 12 inches
but not more than 36 inches. A notch must
be cut with a capacity large enough to dis­
charge anticipated flow to prevent water from
cutting around the edges of the checkdam.
An apron is normally constructed at the face
of the checkdam to prevent erosion. A typical
checkdam is shown in figure 14.
Section IV. CULVERTS
13. CULVERT CONSTRUCTION
Culverts are required to:
Cross roads.
Provide ditch relief.
Continue side ditches at intersections of
roads and access routes.
Factors to consider in selecting culvert sites
are: Bedding conditions.
Cover.
Jamming by debris and ice.
Quantity of flow.
Culverts are designed to carry the maxi­
mum amount of water that is likely to flow
in the drainage channel.
14. CULVERT TYPES
The most common material used for cul­
verts in the TO is corrugated metal pipe
(CMP); CMP is a standard item of issue in
sizes from 12­ to 48­inch diameter (in 6­inch
increments) and 60­ and 70­inch diameters.
Box culverts of timber, logs, or concrete
are often used when CMP is not available.
Concrete and CMP are seldom used in the
construction of expedient roads; however,
when they are available, a considerable sav­
ing in time can be realized.
Improvised culverts which can be con­
structed on the site from local materials, or
fabricated from materials originally used for
other purposes, can save considerable time
and transportation. Examples of these ex­
pedients are:
Open­top culverts made of logs, sized
lumber, or stones.
Sandbags with airfield landing mats.
Petroleum product drums (gasoline, die­
sel, asphalt) with ends removed and tack
welded together.
Note: Extreme care should be used
when removings the heads of
drums that have been used for
petroleum products. Fumes re­
drained and there is extreme
danger of explosions unless all
fumes are removed.
Examples of drum and airfield landing mat
and sandbag culverts are shown in figures
15 and 16.
Examples of log and timber box culverts
are shown in figures 17 through 22.
7­12
7­13
Open top culverts (fig. 17) are generally
used on steep grades where heavy flow is
expected down the road surface. When used
as ditch­relief culverts they are placed at
about 60ø to the centerline of the road.
Empty drum culverts (fig. 15) normally
will require a cradle of wood or other stable
material as a foundation. In order to increase
the load­carrying capacity of these culverts
a distributing layer of logs can be placed over
the culvert after 12 inches of earth has been
placed on top. The logs should be placed
parallel to the centerline of the road with the
ends resting on undisturbed earth. When logs
are not used, a minimum of 3 feet of earth
should be used over the culvert.
Culverts constructed of airfield landing
mats and sandbags (fig. 16) are easily fabri­
cated and can serve a useful purpose for ex­
pedient roads. The mat should be covered
with sandbags or a like material to prevent
the covering soil from filtering through the
openings.
Log box culverts may be constructed with
either a square or rectangular section and
must be designed to prevent side as well as
roof collapse. When the soil beneath the cul­
7­14
vert has low bearing strength, stringers or
sleepers should be used as a foundation. Pre­
ferred method of construction is as shown
in figure 18 with the spreaders and stakes
placed inside the logs to provide greater sta­
bility. This culvert may be modified by placing
the stakes on the outside of the culvert (figs.
19, 20) or by use of sized timber instead of
logs.
Timber box culverts can be built with out­
side bracing or collars, or with internal brac­
ing. Internal bracing should be used whenever
possible since collars do not provide the
rigidity and strength of internal bracing (figs.
21, 22).
15. HEADWALLS AND WINGWALLS
The reasons for construction of headwalls
and wingwalls (figs. 23, 24) are:
Prevent or control erosion.
Guide water into culvert.
Reduce seepage.
Hold ends of culvert in place.
These structures, although necessary, are
expensive in time and materials. Thus, on
the inlet end the culvert should be extended
only so that the minimum length and height
of headwall are required.
Generally they can be omitted on the outlet
except on steep grades, when they are used
to hold the culvert sections in place.
Headwalls should not protrude above grade
and should extend at least 2 feet outside the
shoulder.
When they are not used, the culvert will
be extended at least 2 feet beyond the top
of the fill.
They should be constructed of materials as
durable as the culvert, but sandbags or rubble
can be used in emergency.
16. ALINEMENT AND ELEVATION
Culverts are placed in natural drainage
channels (fig. 25) unless this would require
an unusually long culvert or produce a sharp
bend in the channel on the upstream side.
7­15
Culverts should be installed at a right angle
to the centerline of the roadway (fig. 25)
wherever possible. On sidehill cuts or steep
grades, ditch relief culverts should be in­
stalled at an angle of 60ø to the centerline
for more direct entrance of water into the
culvert.
The elevation at the bottom of the culvert
is placed at or below the level of the stream
bed. When necessary, the culvert may be
placed below the level of the stream bed.
Drop inlets may be used for the purpose, but
extreme care must be exercised to keep them
clean.
EXERCISES
First requirement. Solve multiple­choice
exercises 1 through 5 to show what you have
learned about expedient road materials and
surfaces.
1. Your unit has been assigned the
mission of constructing an expedient
road in preparation for an impending
assault. What are the two basic types
of expedient roads?
a. primary and secondary
b. corduroy and chespaling
c. hasty and heavy
d. temporary and operational
2. It will be necessary for your
unit to quickly construct a road across
a marsh at night. Which of the follow­
ing will characterize that construction?
a. generally constructed of wire mesh
b. built for extremely short life
c. constructed of light, easily handled
materials
d. designed for permanent improve­
ment
3. Your unit is constructing an ex­
pedient road in an area where the sup­
ply of bamboo is adequate to make
bamboo mats. When these mats are
used, in what direction should the long
axis of the bamboo be laid with respect
to the direction of traffic?
a. parallel c. diagonal
b. perpendicular d. interlaced
4. Due to the type terrain to be
crossed, your unit has been instructed
to construct a corduroy road. What is
the general rule for selection of the
type corduroy construction required?
a. the softer the ground, the heavier
the corduroy
7­16
b. diagonal corduroy is preferred un­
der all conditions
c. the softer the ground, the lighter
the corduroy
d. corduroy with stringers is most
substantial, thus is best for all uses
5. A corduroy road is to be con­
structed across swampy terrain. What
can be done to provide a smooth sur­
face on this road?
a. lay the logs perpendicular to the
direction of traffic
b. lay the logs diagonally across the
roadway
c. lay the logs parallel to the direction
of traffic
d. fill the chinks with brush, rubble,
and earth
Second requirement. Solve multiple­choice
exercises 6 through 9 which deal with clear­
ing, grubbing, and stripping.
6. In construction of an expedient
road through a timbered area, an excess
of brush and waste timber has been
accumulated. Of the following, what is
considered as an accepted method of
disposal of these cleared materials?
a. use waste areas or burn
b. use for fill material in the road
c. push to side of the road
d. use for camouflage of the road
7. It is often necessary to remove
major obstacles such as downed timber,
boulders, and brush when constructing
expedient roads. Which of the follow­
ing provides the most rapid and efficient
means of clearing this excess material?
a. explosives
b. pneumatic and gasoline chain saws
c. heavy engineer equipment
d. handtools
8. Your unit has encountered un­
desirable materials such as organic
soils, humus, peat, and muck which
must be stripped in the process of con­
struction of an expedient road. At what
stage of construction should stripping
be accomplished?
a. before clearing and grubbing is
started
b. concurrently with clearing and
grubbing
c. as a last procedure before placing
corduroy
d. after the windrows of rock are re­
moved
9. You are told to select an area
to dispose of the debris resulting from
clearing trees from a roadway under
construction. Which of the following
is the most important consideration?
a. limit interference with natural
drainage
b. create an obstacle at trees line
c. keep piles less than 20 feet high
d. piles should be parallel to roadway
Third requirement. Solve multiple­choice
exercises 10 through 15 which emphasize con­
siderations in drainage of expedient roads.
10. Your unit has been trained to
recognize that drainage is designed to
promote continuous serviceability of
roads. What is the distinguishing char­
acteristic of drainage in the TO?
a. underground, closed drains
b. surface ditching
c. riprapping of ditch walls
d. bypassing of poorly­drained areas
11. In order to overcome the prob­
lems of surface water on roads during
7­17
construction, certain steps should be
taken. Which of the following repre­
sents one of these steps?
a. maintain a rough crown and grade
b. provide ditch relief culverts
c. locate and drain perched water
tables
d. provide outfall ditches
12. The problems of drainage, if not properly solved during the initial stages of construction, can cause con­ tinuous road failures. What are the two
basic types of drainage?
a. ditch relief and culvert
b. snow and rain runoff
c. surface and subsurface
d. design storm and average
13. Your unit must construct
ditches to remove surface water from
its construction site. What are the two
most common types of ditches?
a. trapezoidal and diversion
b. longitudinal and interceptor
c. deep "V" and diversion
d. "V" and trapezoidal
14. Ditches are not only classified
with respect to shape, but also with
respect to function. What kind of ditch
would you build at some distance from
a project in order to prevent water
from reaching and eroding cut and fill
slopes and also to keep water from the
project itself?
a. longitudinal side
b. diversion
c. erosion control
d. interceptor
15. Your unit is constructing a road
through rough terrain where the drain­
age ditches have excessively steep
slopes. What can you construct to slow
the flow of water and reduce erosion
in the ditches?
a. diversion canals
b. checkdams
c. ditch relief culverts
d. interceptor ditches
Solve multiple­choice exercises 16 through
20 to show what you have learned about the
construction of culverts.
16. Your unit is directed to con­
struct culverts to remove water from
a construction site in order to prevent
its interference with other construction
activities. What is the basic require­
ment in designing culverts?
a. drainage of the immediate area
b. carrying the maximum amount of
water that is likely to flow in the
drainage channel
c. placement where the quantity of
flow and velocity is the least
d. acceptance of the minimum free
flow in a specified channel
17. Your crew is installing open top
culverts on steep grades where heavy
water flow is expected on the road sur­
face. When used as ditch relief culverts,
how are they normally oriented?
a. parallel to the centerline of the road
b. perpendicular to the centerline of
the road
c. at about 60ø to the centerline
d. herringbone pattern
18. Your unit is installing expedient
culverts made of petroleum product
drums. Since they have a low com­
pressive strength, what can be done to
increase their load­carrying capacity?
7­18
a. place airfield matting under them
b. use stringers and sleepers under
them as a foundation
c. extend them 3 feet on each side of
the road
d. place a distributing layer of logs
and fill over them
19. Timber box culverts with either
internal bracing or with collars may be
constructed when sized timbers are
available. Why should culverts with in­
ternal bracing be used rather than those
with collars?
a. collars do not provide the rigidity
and strength
b. excessive lumber is required for the
collars
c. excessive cutting and fitting is re­
quired for the collars
d. culverts with internal bracing are
more readily transported
20. In order to conserve materials,
headwalls may sometimes be omitted on
the outlet end of pipe culverts. Why is
it necessary that they be used at the
outlet on steep grades?
a. to prevent erosion back under the
culvert
b. to hold the culvert sections in place
c. to provide an even distribution of
water
d. to provide durability to the outlet
fill
7­19
LESSON 8
MILITARY BRIDGES
CREDIT HOURS _______________________4
TEXT ASSIGNMENT ____________________Attached memorandum.
MATERIALS REQUIRED _________________None.
LESSON OBJECTIVE ___________________To increase your knowledge of military
bridges; their uses, capacities, and
char­
acteristics.
______________________________________________________________________________
ATTACHED MEMORANDUM
Section I. RECONNAISSANCE AND CLASSIFICATION
1. RECONNAISSANCE
Bridges are categorized for military pur­
poses as either existing civilian type or mili­
tary type constructed during field operations.
Reconnaissance of existing bridges may be
hasty or deliberate depending upon the time
and personnel available.
The factors to consider in selecting a bridge
site are:
Access roads.
Approach roads.
Character and shape of banks.
Stream flow characteristics.
River bottom conditions.
Availability of construction resources.
Existing natural concealment.
The information needed to plan construc­
tion on existing bridges includes:
Type and dimensions of abutments.
Type and dimensions of supports.
Number, type, size, and spacing of
stringers.
Type and dimensions of flooring.
Work estimate to restore to original
capacity.
Work estimate to strengthen to attain
specified capacity.
2. CLASSIFICATION
Before a driver can determine whether or
not his vehicle may cross a given bridge, he
must know the classification of his vehicle
and the classification of the bridge. If the
classification of his vehicle is equal to or less
than the classification of the bridge, he may
cross. Signs on the vehicle and bridge tell
him their classification. The driver must also
know the height of his vehicle as compared
to the overhead clearance of the bridge.
The classification number assigned to a
vehicle represents the loading effect of the
vehicle on a bridge. The classification number
does not represent the actual weight of the
vehicle. The bridge classification number rep­
resents the safe military loading capacity of
the bridge in terms of vehicle classification.
All army vehicles, except those with a gross
weight of less than 3 tons, and trailers with
a rated payload of 1 1/2 tons or less, are classi­
fied. FM 5­36 lists classification numbers for
most standard U.S. military vehicles.
Vehicles not listed in FM 5­36 may be
given a temporary class by the expedient
vehicle classification method as follows:
8­1
Temporary Class (wheeled vehicles) =
0.85 x Gross Weight in tons
Temporary Class (tracked vehicles) =
Gross Weight in tons
Example 1. A truck assigned to an engineer
float bridge company has a gross weight of
24 tons. What class would you assign to this
wheeled vehicle?
Solution: By using the expedient vehicle
classification method,
Temporary Class = 0.85 x Gross Weight = 0.85 x 24 = 20.4, say 21 tons
= 21
A combination vehicle is a vehicle con­
sisting of two or more single vehicles which
operate as one unit. If one vehicle is towing
another and the distance between them is
less than 30 yards, they must be considered
as a combination vehicle.
The class of a combination vehicle is ob­
tained as follows:
Add the class of one vehicle to the class of
the other. If the sum is more than 60, such
sum is the classification of the combination
vehicle. If the sum is 60 or less, the classifica­
tion of the combination vehicle is .9 x the
sum.
Example 2. A class 28 tractor is towing a
class 20 trailer with a 35­foot chain. What
is the class of this combination?
Solution: 28 + 20 = 48 and 48 is less than 60
Combination Class = 0.9 (28 + 20)
= 43.2, say 44
= 44
Bridges may be given a dual classification
when the capacity is greater than class 30.
3. MARKING
Bridge classification signs give the bridge
class.
The signs in figure 1 give the following
information:
Sign (a), shows one­way classification
and the minimum sign diameter.
Sign (b), shows classification for a two­
lane bridge and the minimum sign diam­
eter; 34 and 48 are, respectively, the
vehicle classification limits when vehicles
are traveling two ways and one way.
Sign (c), shows one­way classification
for wheeled and tracked vehicles.
Sign (d), shows two­lane classification
for both wheeled and tracked vehicles.
Sign (e), shows one­way classification
with width limitation.
8­2
A special class number represents the load­
carrying capacity of a bridge under special
crossing conditions. These numbers are not
posted on standard bridge marking signs, but
on supplementary signs.
A normal crossing is defined as one in
which the vehicle class number is equal to
or less than the bridge classification number,
where vehicles maintain 30­yard gaps, and
where speed is restricted to 25 miles per hour.
Special crossings are authorized by the
local tactical commander under exceptional
operating conditions and are either caution
or risk crossings.
Caution crossings permit vehicles to cross
whose classification is up to 25 percent above
the capacity of the nonstandard bridge.
Risk crossings may be made only on stan­
dard prefabricated fixed and floating bridges.
Section II. FIXED BRIDGES
4. INTRODUCTION
In general, the term fixed bridge includes
all but floating bridges.
Military bridge construction in a theater
of operations normally is limited to temporary
and semipermanent structures. A temporary
bridge is one designed to meet immediate
tactical and supply needs, while a semiper­
manent one is intended to last at least until
the end of hostilities.
Standard fixed bridges are stock items
available for issue from U.S. Army supply
centers. The remainder of this section is
concerned with nonstandard fixed bridges
which are constructed from supply system
and locally available materials, and designed
to meet the requirements of a particular site.
In the construction of temporary and semi­
permanent military bridges the principal ma­
terials used are timber and steel.
Span lengths of timber stringers are limited
to 25 feet. Steel stringer spans range from
25 to about 60 feet.
Decks distribute the live load to the
stringers. Abutments provide support for the
superstructure on the banks of the gap.
Figures 2 through 10 illustrate the various
components of nonstandard fixed bridges and
their nomenclature.
Nonstandard fixed bridges include:
Timber stringer bridges­­used exten­
sively in the theater of operations for
short span crossings or a multiple of
short spans for longer crossings. The
spans are simply supported and rarely
exceed 20 feet. The deck normally is
either plank or laminated timber decking.
Steel stringer bridges are used in simply
supported spans up to 90 feet and in
continuous span bridges with clear spans
up to 120 feet. Steel stringers consist
of either standard rolled shapes or beams
built up with welded steel plates.
Other nonstandard fixed bridges encoun­
tered in the theater of operations in­
clude: reinforced concrete T­beam
bridges, composite steel­concrete stinger
bridges, steel girder bridges, truss
bridges, suspension bridges, and arch
8­3
8­4
bridges. The military does not often con­
struct these types of bridges but may be
tasked to repair, reinforce, or classify
them.
8­5
5. DESIGN
The design of nonstandard, semipermanent
fixed highway bridges is basically a two­phase
process. First is the determination of the
design loads. Second is the selection of mem­
bers of sufficient strength to resist the effects
of the loads on the bridge.
The dead load is the weight of the bridge
itself, to include the weight of the stringers,
the deck, and accessories. The accessories
include the curb and handrail system, lateral
bracing, and hardware and connection ma­
terials. The design live load is the maximum
vehicle class for which the bridge is designed.
The most economical bridge, considering
both materials and construction efforts will
normally contain the minimum number of
stringers. The maximum center­to­center
spacing of stringers in timber­decked bridges
is 6 feet; for concrete decks, 8 feet.
The deck system includes the deck, the
wearing surface that protects the deck, and
the curb and handrail system. The plank
deck is the simplest to design and construct,
and provides considerable savings in time
compared to other types of decking. The
minimum thickness of deck is 3 inches in all
cases. Plank decking is normally placed per­
pendicular to the bridge centerline (direction
of traffic) for ease and speed of construction.
A better structural arrangement is pro­
vided if the decking is placed at a 30­45ø
skew to the centerline. A space of about
1/4 inch should be provided between the planks
8­6
to allow for swelling, to provide better water
drainage, and to permit air circulation.
When the required thickness of plank deck­
ing exceeds 6 inches use a laminated type
decking. Normally a thick deck is required
for large stringer spacing and the higher
design classes. A laminated deck is much
stiffer than a plank deck.
6. ABUTMENTS
Fixed bridge abutments include many
types. The timber sill abutment can be used
to support tion up to 25 feet long. They are
used on highway bridges and are not more
than 3 feet high.
Timber bent abutments are used with steel
or timber stringers on highway bridges with
8­7
spans up to 30 feet. A deadman is used to
provide horizontal stability. They do not ex­
ceed 6 feet in height.
Timber or steel pile abutments may be used
to support spans of any length. They use
steel or timber stringers and can reach a
maximum height of 10 feet.
Mass or reinforced concrete abutments will
also support any span length and may be as
high as 20 feet. They are the most perma­
nent type and can support either steel or
timber stringers.
7. BENTS AND PIERS
Bents and piers provide support for the
superstructure at points in the gap other
than the banks. A bent consists of a single
row of posts or piles, while a pier consists
of two or more rows of posts or piles.
8­8
Spans on pile bents usually can be used
economically for crossings of shallow
streams, swamps, tidal waters ,and floodways
in wide valleys. Pile piers, consisting of two
pile bents driven close together and united
into a rigid structure by bracing, are most
economical for bridges of intermediate height
and longer spans across narrow streams and
floodways.
Timber crib piers are constructed of logs
stacked on each other in log­cabin fashion
and filled with rock for ballast if desired.
They can support a combined span length of
50 feet and may have a ground to grade
height of 12 feet.
Timber trestle bents and piers normally
are constructed in dry shallow gaps in which
the soil is firm. They are not suitable for
use in soft soil or swift or deep streams. The
bent can support a combined span length up
to 30 feet and can be 12 feet high. The pier
can be 18 feet high with a capacity to support
a 60­foot combined span length.
A timber pile bent consists of a single row
of piles with a pile cap. It should be braced
to the next bent or to an abutment in order
to reduce the unbraced length and to provide
stability. This bent will support a combined
span length of 50 feet.
Timber pile piers will support combined
span lengths of 200 feet. A steel pile bent
will support a 70­foot combined span length,
while a steel pile pier will support any span
length. In all cases where piles are used, the
height of the structure is governed by the
unbraced length of the piles.
Concrete piers are normally used in per­
manent bridges rather than in semiperma­
nent bridges.
8. PANEL BRIDGE, BAILEY TYPE, M2
The Panel Bridge, Bailey type, M2 (fig. 11)
is a through­truss bridge supported by two
main trusses formed from 10­foot steel
panels, called bays. The bridge is used both
as a tactical bridge and a line of communica­
tions bridge. It is valuable to field com­
manders because of its ease of construction,
speed of construction, mobility, and versa­
tility.
The engineer panel bridge company is the
TOE unit designated to carry one bridge set
and provide technical personnel and equip­
ment to transport and supervise erection of
panel bridging (see table 1). The bridge parts
may be transported on twenty­five 5­ton dump
trucks and eight pole trailers. The loading
plan is based on the experience that the
double­single truss assembly provides for
most bridging problems which require the
panel bridge.
The abbreviated nomenclature of the var­
ious types of truss assemblies is given by two
letters. The first letter specifies the number
of trusses. The second letter specifies the
number of stories.
Example 3. What does the abbreviated no­
menclature DS describe?
Solution: DS = double­truss, single­story
(see table 2).
Trusses may be one, two, or three panels
wide and up to three panels high. The only
trusses not erected are the single­truss,
double­ or triple­story because they would
be unstable.
When triple­story bridges (double­ or
triple­truss) are erected with the deck in the
bottom story they must be braced at the top
by transoms and sway braces.
The class of existing single­ and double­
truss bridges can be increased by the addition
of extra trusses. Construction starts from
the center of the bridge, and panels are added
toward each end. The class of existing single­
story bridges can also be increased by adding
extra stories.
The bridge set contains 33 different items
of bridge parts and 30 different items of erec­
tion equipment which are enough for two
80­foot DS bridges or one 130­foot DD bridge.
Each set has 126 panels (weighing 577 pounds
each), 56 transoms (618 pounds each), 48
ramps (338 to 349 pounds each), and chess,
end posts, bracing, and erection equipment.
8­9
8­10
The panel is the basic member of the bridge.
Panels are joined end to end by panel pins
through the male and female lugs.
The transom supports the floor system of
the bridge. They rest on the lower chords
of the panels and are held in place by transom
clamps.
The raker connects the end of the transom
to the top of the panels of the inner truss
and prevents the panels from overturning.
At each end of the raker is a hollow dowel
for the bracing bolts; it fits through a hole in
the panel and a hole in the transom.
The bracing frame is used to brace the
inner two trusses on each side of the double­
and triple­truss bridge. Bracing bolts attach
the bracing frames horizontally to the top
chords of the bridge and vertically on one
end of each panel in the second and third
stories. The sway brace is hinged at the
center, and adjusted by a turnbuckle. At
each end is an eye, through which a pin on
a chain is inserted to secure it to the panel.
The sway brace is given the proper tension
by inserting the tail of an erection wrench
in the turnbuckle and screwed up against the
turnbuckle. Two sway braces are required
in the lower chord of each bay of the bridge
and all except the first bay of the launching
nose, and in each bay of overhead bracing.
The tie plate is used only in triple­truss
bridges; it secures the second truss to the
third truss, using the unoccupied raker holes
in the panels at each joint and at the ends
of the bridge.
Chord bolts join the panels one above the
other to form double­ and triple­story bridges.
Two bolts per panel pass upward through
holes in the chords of the panels and are
tightened with nuts on the lower chord of
the upper story. They are also used to fasten
overhead bracing supports to the top panel
chord.
Stringers carry the roadway of the bridge.
There are two types of stringers: plain
stringers weighing 260 pounds, and button
stringers weighing 267 pounds. They are
identical except that the latter has 12 buttons
which hold the ends of the chess in place.
Each bay of the bridge has six stringers:
four plain stringers in the middle, and a but­
ton stringer on each side. The stringers are
positioned by the lugs on the top of the
transoms.
Chess form the road surface. Each bay of
the bridge contains 13 chess, which lie across
the stringers and are held in place by the
buttons on the stringers. Chess are held
down by ribands. The steel riband (guard
rail) is fastened to the button stringer by
four J­type riband bolts. The clear roadway
between ribands is 12 feet 6 inches.
The riband bolt fastens the riband to the
button stringers and ramps. The hook end
of the bolt grips the lower flange of the outer
I­beam of the button stringer or ramp.
End posts are used on both ends of each
truss of the bridge to take the vertical shear.
They are placed only on the story carrying
the decking. They are 5 foot 8 inch columns
made of two 4­inch channels and plates
welded together. There are two types, male
and female, having male and female lugs,
respectively. These lugs are secured to the
end panels of the bridge by panel pins through
holes in the lugs. The male and female end
posts weigh 121 and 130 pounds, respectively.
End posts have a step to support a transom
outside the panel at one end of the bridge.
In jacking the bridge, the jack is placed under
the step. The lower end of the end post has
a half­round bearing block which fits over
the bearing.
The bearing spreads the load of the bridge
to the base plate. A bearing is a welded steel
assembly containing a round bar which, when
the bridge is completed, supports the bearing
blocks of the end posts. During assembly of
the bridge, it supports the bearing block of
the rocking roller. The bar is divided into
three parts by two intermediate sections that
act as stiffeners.
The base plate is a welded steel assembly
with built­up sides and lifting­hook eyes on
the top at each corner. It is used under the
bearings to spread the load from the bearings
8­11
over the ground or grillage. The area of the
bottom surface of the base plate is 13 V2
square feet. The base plate weighs 381
pounds and is large enough for the bearings
at one corner of a single­, double­, or triple­
truss bridge. Bearings can slide 9 inches lon­
gitudinally on the base plate. The numbers 1,
2, and 3 are embossed on the edges of the
base plate to indicate the position of the plate
under the inner truss of single­, double­, and
triple­truss bridges respectively.
Ramps are similar to stringers, but consist
of three 5­inch, instead of 4­inch, steel I­
beams. They are 10 feet long and are joined
by welded braces. The lower surface of the
ramp tapers upward near the ends. There are
2 types of ramps: plain ramps weighing 338
pounds, and button ramps weighing 349
pounds. They are identical except the latter
has 12 buttons which hold the ends of the
chess in place.
Four plain and two button ramps are
used as continuations of the stringers and
lead from the bridge to the banks. If the
slope is too steep, ramps are joined end to
end on transoms supported by ramp pedes­
tals. This type of ramp construction is con­
tinued as far as required to provide the slope
called for by the class of expected traffic. For
loads of 45 tons or over, the ramps are sup­
ported at their midpoints by timber cribbing
and wedges. The ends of the ramps fit into
lugs on the transoms at the ends of the bridge.
Ramp pedestals are built­up welded steel
assemblies weighing 93 pounds. They
prevent the transoms supporting multiple­
length ramps from overturning and spreading
the transom load over the ground. They are
held in place by spikes or pickets driven
through holes in their base plates.
Supported on footwalk bearers, footwalks
are laid along the outer sides of the bridge for
use by foot troops. Footwalks are constructed
of wood.
Footwalk bearers are attached to all tran­
soms except reinforcing transoms, fitting over
and under special lugs welded to the web near
the ends of the transom. The footwalk fits be­
tween lugs on top of the bearers. A socket at
the end of the bearer holds the footwalk post.
A footwalk post is fitted into every footwalk
bearer.
Hand ropes are threaded through two eyes
on each post and secured either to holdfasts
on the banks or to the end footwalk posts.
The overhead bracing support is used to
clamp overhead transoms and sway braces to
trusses for overhead bracing of triple­story
bridges. The frame is a welded metal assemb­
ly that weighs 150 pounds. It is fastened to
the tops of third story panels by means of
chord bolts. A transom is seated over the
pintles on top of the frame and secured by
cleats over the lower flange held by 4 nuts and
bolts.
A skeleton launching nose is employed
in launching the bridge. The bridge is as­
sembled on rollers on one bank and then
pushed across the gap utilizing the cantilever
method. This method keeps enough weight
behind the rollers to balance the bridge and
prevent its tipping into the gap.
8­12
8­13
Section III. FLOATING BRIDGE EQUIPMENT
9. LIGHT STREAM­CROSSING EQUIPMENT
The aluminum floating footbridge (fig. 12)
provides a standard means of crossing foot
troops rapidly. The footbridge set furnishes
472 feet 6 inches of bridge, and can be used
in currents up to 11 feet per second.
One bay of bridge which provides 11 feet
3 inches of bridging, consists of one pon­
ton, one treadway, and four handrail
posts. The bridge is erected by succes­
sively connecting individual bays to the
near shore end and pushing the entire
bridge toward the far shore.
Capacity, in men per minute with a cur­
rent velocity up to 8 feet per second, is:
day­­75; moonlight­­40; blackout­­
25. This is based on troops crossing
single file at a 2­pace interval in daylight
and moonlight at double time. Reduce
the capacities by 20 percent in currents
of 9­11 fps.
Normally, one­half the quantity of each
component of the set is carried on a com­
bination vehicle consisting of a 2 1/2­ton
cargo truck towing a 2 1/2­ton utility pole
type or 4­ton bolster type trailer. The
bridge set can also be carried on three
2 1/2­ton cargo trucks, each carrying one­
third of the major components. One
complete set of aluminum footbridge is
air transportable in one C­130 airplane.
Guy lines are needed in any current
velocity to maintain alinement of the
bridge because the treadway joint pro­
vides little lateral strength.
Assembly of the bridge begins on the
near shore by laying a treadway across
two pontons (forming an H­bay) 80 that
the small lugs beneath the stringer at
each end of the treadway fall inside the
gunwales of the pontons.
Then, the two spring­actuated retainers
on the downstream side of the ponton
are flipped into position to hold the down­
stream side of the treadway in place.
Each bay following the first bay, an
H­bay, is in the shape of a T with the tail
of the T pointing inshore.
Each ponton has two holes (1 inch x 2
inch), one in the bow and one in the
stern, just above the false bottom to
make the ponton self­bailing.
8­14
The light tactical raft (fig. 13) can be used
to assemble either rafts or floating bridges.
Both raft and bridge consist of a deck built
of aluminum sections supported on aluminum
pontons.
With a trained crew, during daylight
hours, and in still water, this bridge can
be hand erected at a rate of 3 1/2 feet per
minute. Time and manpower required
for assembly of light tactical rafts:
Four­ponton,
three­bay = 3 NCO 27 EM @ 30
minutes
Five­ponton,
five­bay = 3 NCO 27 EM @ 35
minutes
Six­ponton,
four­bay = 3 NCO 27 EM @ 45
minutes
Each bay provides 11 feet of bridging
with a deck width of 9 feet.
This equipment is issued as a light tacti­
cal raft set. The light tactical raft com­
ponents normally are transported on two
2 1/2­ton cargo trucks and one 2 1/2­ton
pole type or 4­ton bolster type trailer.
The raft is assembled with overhanging
ramps. Articulated panels can be in­
stalled in the ramps if the site requires
changes in ramp elevation.
8­15
10. HEAVY STREAM­CROSSING EQUIPMENT
This type of equipment is used when vehi­
cles and other heavy equipment must cross
a stream.
The class 60 floating bridge (fig. 14) bay
consists of two steel deck­tread panels, two
curbs, and one filler panel with an effective
bridging length of 15 feet and a roadway
width of 166 inches. The floating support for
one bay consists of two 24­ton pneumatic
floats spaced 15 feet center­to­center.
The deck panels are pinned together end­
to­end to provide rigid connections. The
deck has the stiffness to transmit the
load of class 65 vehicle to approximately
10 floats, with only minor deflection.
The standard bridge set contains com­
ponents for the complete assembly of
one floating bridge 135 feet long. This
does not include the length of the 16
foot tapered ramp used at each shore
connection or the length of two short
(5 ft) bays of superstructure by which
the length of shore connections can be
increased.
The number of rafts which can be as­
sembled from the set is limited to one
because the raft requires the use of the
two ramp bays in the set.
The superstructure bay is assembled
from two deck­tread panels, one deck­
filler panel, and two curbs. One ramp
bay is used in each shore connection. It
is assembled from two ramp­tread
panels, one ramp­filler panel, and four
short deck curbs.
Ramp stiffeners are issued as a part of
the bridge set. They are needed when
abutment conditions are likely to bring
about a major difference in settlement
between two adjacent deck panels. Once
used, the stiffener assembly usually can­
not be reused because the members bend
with use of the bridge.
Usually, one 6­by­6 military bridge truck
carries a complete 15­foot bay of bridge,
including a 24­ton float, saddle assembly,
and deck components. The bridge set is
a part of the equipment of the Engineer
Float Bridge Company. This unit is
equipped with two truck­mounted crane­
shovel units, 20­ton 3/4­cubic yard, gaso­
line­driven which are used in the as­
sembly of the bridge. Air compressors
are required to inflate the pneumatic
floats.
8­16
The M4T6 floating bridge (fig. 15 ) is a
hand erected high capacity bridge. It is built
by combining the deck balk from the M4 float­
ing bridge and the pneumatic floats from the
Class 60 floating bridge. These components
are combined through the use of deck balk
connecting stiffeners and saddle adapters. An
air compressor is required for assembly. The
saddle assembly for a float includes eight
interior and two end saddle panels, and two
saddle beams. The deck forms a continuous
beam action over the pontons and provides
an effective bridging length of 15 feet per
bay with a roadway width of 166 inches.
One M4T6 bridge set can be used to
construct one 141­foot 8­inch floating
bridge or one 4­float and one 5­float rein­
forced raft.
The pneumatic float consists of 2 identi­
cal half­floats, each 9 by 22 feet, joined
stern­to­stern to form a complete float
9 feet wide, 44 feet long, 3 feet high.
Each half­float is made up of three tubes
laced together longitudinally. Each tube
is divided into four inflation chambers,
fitted with a valve. The half­float weighs
750 pounds.
Three types of aluminum deck balk are
used in the bridge: normal, short, and
tapered. The balk are watertight and
will float. The components of the bridge
can be carried on any standard military
cargo truck or trailer having a rated
capacity of 2 1/2 tons or more. Handrail
posts are metal rods 3 feet 3 inches long
used to mark the roadway of bridges.
Standard kedge anchors weighing 100
pounds are used for anchoring the bridge
when stream conditions permit. Pre­
fabricated holdfasts for use with the
anchorage system are issued with the
bridge set. Nine steel pickets and a
length of chain constitute each holdfast.
8­17
The M4T6 floating bridge is class 50 for
normal crossings in currents up to 3
feet per second.
The rafts normally assembled from the
bridge set are ­­ 4­float normal raft,
4­float reinforced raft, and the 5­foot
reinforced raft.
To increase bridge capacity, reinforced
floating sections are constructed by plac­
ing the floats closer together than for
normal construction and using offset
saddle adapters.
Four deflated air rollers are positioned
at the launching site 80 that two half­
floats are unloaded from the truck onto
them.
After the floats are completely assem­
bled and ready for launching, the air
rollers beneath them are then inflated
and the float assembly is launched.
After the launching, the float inflating
crew retrieves the air rollers. The rollers
are repositioned, and their valves opened
allowing them to deflate.
Section IV. ANCHORAGES, BOATS, REINFORCEMENT AND REPAIR
11. ANCHORAGES FOR FLOATING BRIDGES
Shore guys are used primarily to hold the
bridge during assembly. If the current does
not exceed 3 feet per second, shore guys are
used as a primary anchorage.
Kedge anchors lie in the stream bed and
are secured to the bays or rafts with anchor
lines. The kedge anchor depends on the stream
bed for holding power, and is useful only when
the bed is composed of sand, silt, loose rock,
or other material into which the fluke can
take hold.
Combinations of kedge anchors and shore
guys may be used in stream velocities of 5
feet per second or less.
Overhead cable systems consist of one or
more tower­supported cables spanning the
river parallel to the bridge on the upstream
side. Bridle lines are used to make the bridge
secure to the cable.
Deadmen are used at each end of the
bridge to anchor the main cables.
12. BOATS The pneumatic assault boat is made of
nylon fabric with a capacity of 15 men with
equipment. It has 10 separate air compart­
ments and weighs approximately 250 pounds.
The 27­foot bridge erection boat is gasoline
powered aluminum, twin­screw, 2­section
aluminum­alloy hull boat. It is used to propel
the heaviest types of rafts assembled from
floating bridge sets. The boat is powered
by two separately controlled, 6­cylinder, 90­
horsepower marine type gasoline engines.
When carrying cargo, the maximum allow­
able load is 3,000 pounds.
The latest version of the bridge erection boat,
referred to as Bridge Erection Boat, Shallow
Draft (BEB­SD), is an easily transported,
hydrojet propelled, shallow draft, aluminum
hulled boat designed to maneuver com­
ponents of floating bridges. The boat can also
8­18
be used to propel rafts, support diving opera­
tions, assist in maritime construction
projects, serve as a troop and cargo carrier,
and patrol inland waters. The boat is powered
by two 6 cylinder, 212 horsepower water
cooled diesel engines, which will provide an
unloaded top speed of 21.6 mph, and a fully
loaded (4400 lbs) speed of 16.2 mph.
13. REINFORCEMENT AND REPAIR
Existing timber floors may be reinforced
by adding an additional layer of decking and
tread.
Stone masonry bridges can be patched up
with concrete. Cracks can be repaired by
banding the structure with steel straps or
beams which are pulled tight in a direction
tending to close the crack.
Posts may be reinforced by nailing two
6 x 8's to cap and sill and to the posts be­
tween.
Knee­braces, A­frames, and king or queen
trusses can be used to provide additional sup­
port for stringers.
Steel floorbeams may be reinforced by
welding plates to the top and bottom flanges,
provided the two flanges can be exposed.
The reinforcing of trusses by adding in­
termediate supports is the simplest and most
effective means of strengthening. When steel
truss members have been damaged by bend­
ing or twisting, it is best to replace them by
new fabricated sections identical to the orig­
inal parts.
8­19
EXERCISES
First requirement. Multiple­choice exer­
cises 1 through 8 provide an opportunity for
you to test your knowledge of preliminary in­
vestigations, classification, and marking of
military bridges.
1. Many factors must be consid­
ered in selecting a site for bridge con­
struction. Which of the following
characteristics would you consider in
the selection of a site?
a. type of bridge supports
b. character and shape of banks
c. dimensions of supports
d. spacing of stringers
2. You have received information
about the condition of an existing bridge
which was gathered during a recent
reconnaissance. Which of the choices
given would you use in planning for
construction on an existing bridge?
a. stream flow characteristics
b. river bottom condition
c. dimensions of abutments
d. existing natural concealment
3. You are driving a 5­ton truck
and approach a timber trestle bridge.
The bridge class posted on a sign near
the bridge is larger than the classi­
fication number assigned to your vehi­
cle so you may cross. What does the
vehicle classification represent?
a. loading effect on a bridge
b. weight distribution of the vehicle
c. gross weight of the vehicle
d. weight of the maximum load
4. Vehicles not listed in FM 5­36
may be given a temporary class by the
expedient vehicle classification method. A wheeled vehicle has a gross weight
of 20 tons. What is its temporary class?
a. 11 c. 15
b. 13 d. 17
5. You are driving a vehicle of
class 40 which is towing another vehicle
of class 19. If the distance between
them is 29 yards, what is the combina­
tion class?
a. 44 c. 54
b. 49 d. 59
6. You are in charge of four vehi­
cles and must cross a bridge with the
classification as depicted in figure 16.
Which of your vehicles must cross when
there is no oncoming traffic on the
bridge?
a. tank (class 24)
b. grader (class 26)
c. dozer (class 27)
d. tractor­trailer (class 29)
8­20
7. In a normal crossing the vehi­
cle's class number is equal to or less
than the bridge classification number
and the vehicles maintain 30­yard gaps.
What is the maximum speed in miles
per hour you are restricted to in a
normal crossing?
a. 10 c. 20
b. 15 d. 25
8. The second bridge your small
convoy encounters is a one­lane, class
20, timber trestle bridge which spans
a gap of 29 feet. Which of your vehicles
is the largest that can use this bridge
in a caution crossing?
a. tank (class 24)
b. grader (class 26)
c. dozer (class 27)
d. tractor­trailer (class 29)
Second requirement. Solve multiple­choice
exercises 9 through 19 to show what you have
learned about fixed bridges.
9. You are assisting in planning
the construction of a timber trestle
bridge. What is the limit, in feet, for
span lengths of timber stringers?
a. 20 c. 30
b. 25 d. 35
10. The deck system on a bridge
includes the deck, the wearing surface
that protects the deck, and the curb
handrail system. What is the main
purpose of the deck?
a. provides a smooth surface for
traffic
b. protects the stringers from wear
and tear
c. adds strength to the superstructure
d. distributes the live load to the
stringers 11. You are designing a nonstan­
dard, semipermanent fixed highway
bridge as basically a two­phase process.
Determination of the design loads was
the first phase. What would be the
second?
a. selection of members
b. determining the bridge class
c. selection of crews
d. establishing a centerline
12. You have ascertained that the
most economical bridge contains the
minimum number of stringers. What
is the maximum center­to­center spac­
ing of stringers you could use in timber­
decked bridges in feet?
a. 4 c. 6
b. 5 d. 7
13. You are placing plank decking
perpendicular to the bridge centerline.
What is the minimum required thick­
ness of all decking, in inches?
a. 2 c. 4
b. 3 d. 5
14. You have decided to use a lami­
nated deck because it is much stiffer
than a plank deck. Laminated decking
is used when the plank decking required
exceeds how many inches?
a. 6 c. 8
b. 7 d. 9
15. After studying several sites for
a new bridge, you recommend to your
platoon sergeant the site where a pile
abutment could be constructed at one
end. What is the maximum height, in
feet, to which a timber or steel pile
abutment could be constructed?
a. 4 c. 8 b. 6 d. 10
8­21
16. At the other end of the bridge
you recommend a timber bent abut­
ment. What is the maximum span
length, in feet, which a timber bent
abutment will support?
a. 25 c. 35
b. 30 d. 40
17. The timber crib piers you con­ structed of logs stacked on each other in log­cabin fashion and can support a
combined span length of 50 feet. What
is their maximum ground to grade
height, in feet?
a. 8 c. 12
b. 10 d. 14
18. Timber trestle bents and piers
can only be used when certain favorable
conditions exist. Under which of the
following conditions might you choose
to use a timber trestle bent?
a. soft soil c. deep stream
b. swift stream d. firm soil
19. A steel pile bent will support
a 70­foot combined span length, while
a steel pile pier will support any length.
What factor governs the height of these
structures?
a. unbraced length of the piles
b. velocity of stream
c. maximum span length supported
d. dead load of superstructure
Third requirement. Multiple­choice exer­
cises 20 through 22 relate to the panel bridge,
Bailey type.
20. Your unit has built a Bailey
bridge which is a through­truss bridge
used both as a tactical and a line of
communications bridge. The bridge is
described as being two stories high with
three trusses. What is the abbreviated
nomenclature for this assembly?
a. DT c. DD b. TS d. TD
21. Your company has the mission
to erect a 130­foot DD bridge from one
bridge set. Your squad is to install the
ribands. What is the clear roadway,
in feet, between the ribands?
a. 8.6 c. 12.5
b. 11.0 d. 15.0
22. Your platoon has assembled a
Bailey bridge on rollers and pushed it
across the gap, with enough weight kept
behind the rollers to balance the bridge
and prevent its tipping into the gap.
What is this method of launching called?
a. cantilever c. flotation
b. cableway d. crane
Fourth requirement. Solve multiple­choice
exercises 23 through 35 to test your under­
standing of floating bridge equipment.
23. Your squad has assembled 8 in­
terior and 2 end saddle panels, and 2
saddle beams. What is this configura­
tion called?
a. substructure assembly
b. saddle adapted assembly
c. saddle assembly
d. reinforced float assembly
24. The capacity of the footbridge
is normally dependent on the stream
velocity and the degree of visibility.
What is the footbridge capacity, in men
per minute, in a stream velocity of 7
feet per second during daylight hours?
a. 55 c. 85
b. 75 d. 95
25. You can use the light tactical
raft as both a raft and a floating bridge.
At what rate, in feet per minute, can
8­22
this bridge be erected by a trained
crew?
a. 3.5 c. 6.5
b. 5.0 d. 8.0
26. Your unit has erected a light
tactical raft (LTR). Each bay of the
LTR provides 11 feet of bridging. How
wide is the deck of this bridge, in feet?
a. 6 c. 8
b. 7 d. 9
27. The class 60 floating bridge bay
has an effective length of 15 feet. How
many feet of bridge can you erect with
one set?
a. 110 c. 150
b. 135 d. 175
28. Only one raft can be assembled
from the class 60 bridge set. What is
the reason for this?
a. superstructure bay requires two
curbs
b. bridge bay requires two deck­tread
panels
c. raft requires two ramp bays
d. each shore connection requires a
tapered ramp
29. Ramp stiffeners are issued as
a part of the class 60 bridge set. For
what purpose would you use them?
a. prevent different settlement in ad­
jacent panels
b. increase the capacity of the super­
structure
c. prevent the collapse of inflated
pneumatic float
d. increase the strength of the alumi­
num pontons
30. The M4T6 floating bridge is
built by combining deck balk from the
M4 floating bridge with pneumatic floats
from the Class 60 floating bridge. Which
of the following equipment do you use
to combine these components?
a. filler panel
b. saddle adapters
c. tapered ramps
d. short bays
31. The M4T6 floating bridge has a
roadway width of 166 inches. How
many feet of bridge can you erect with
one set?
a. 114.40 c. 134.40
b. 121.66 d. 141.66
32. The M4T6 bridge components
are carried on standard military cargo
trucks. What is the minimum rated
capacity, in tons, of the trucks that you
can use for this purpose?
a. 3/4 c. 5
b. 2 1/2 d. 10
33. It is important for you to take
into account the velocity of the stream
in determining the class of floating
bridges. What class M4T6 floating
bridge would you assign for normal
crossings in currents up to 3 feet per
second?
a. 30 c. 50
b. 40 d. 60
Fifth requirement. Multiple­choice exer­
cises 34 through 38 deal with anchorages,
boats, and reinforcement and repair of
bridges.
8­23
34. Shore guys are used primarily
to hold the bridge during assembly.
What is the maximum stream velocity,
in feet per second, which limits the use
of shore guys as primary anchorage?
a. 3 c. 7
b. 5 d. 9
35. You have used a combination
of kedge anchors and shore guys in a
stream with velocities up to 5 feet per
second. What does the kedge anchor
depend on for holding power?
a. anchor cable c. deadman
b. bridle lines d. stream bed
36. Boats are used in the theater
of operations to assemble floating
bridges, to propel tactical rafts, to help
with general utility work, and to cross
troops. Which of the following boats
carries the fewest personnel?
a. 19­foot bridge erection boat
b. M2 assault boat
c. 16­foot plastic assault boat
d. pneumatic assault boat
37. It is sometimes necessary to
reinforce existing structures. You
would use knee­braces, A­frames, and
king or queen trusses to reinforce which
bridge members?
a. floors c. posts
b. piers d. stringers
38. Adding intermediate supports
is the simplest and most effective means
of strengthening trusses. What is the
best procedure when steel truss mem­
bers have been bent or twisted?
a. welding c. replacing
b. banding d. reinforcing
8­24 LESSON 9
Expedient Stream Crossings
CREDIT HOURS_______________________2
TEXT ASSIGNMENT____________________Attached memorandum.
MATERIALS REQUIRED ________________None.
LESSON OBJECTIVE __________________To provide you with a working knowledge
of expedient river crossing devices to in­
clude the use and assembly of expedients
from materials available through normal
supply channels and native materials avail­
able at or near the site. _____________________________________________________________________________
ATTACHED MEMORANDUM
Section I. GENERAL
1. INTRODUCTION
Expedient stream crossings are stream
crossings made when time is a limiting factor,
and serviceable bridges and standard raft
materials are not available.
The tactical situation will normally be the
factor which will determine the urgency of
the stream crossing, and therefore the sim­
plicity or complexity of the method chosen.
This lesson will illustrate several expedient
methods that may be used for stream cross­
ings. Many other methods may be developed,
depending upon imagination and ingenuity.
2. DETOURS
When a stream must be crossed and an
existing bridge at the intended crossing site
has been damaged beyond serviceability, you
should first investigate the possibility of a
detour.
In determining whether to use a detour,
or alternate route, you must consider whether
it is available immediately or only after some
delay, how much more travel time is involved,
how much labor will be saved, and how much
exposure there may be to enemy action.
3. EMERGENCY REPAIRS
If a damaged bridge exists, and there is
no suitable detour available, consideration
should be given to the possibility of making
emergency repairs to the bridge and utilizing
any part of the existing structure which may
be useable. This may frequently turn out to
be the most expedient means of crossing a
stream. Before attempting such repair, con­
sideration must be given to the following:
Type of bridge.
Nature of damage.
Tactical situation and bridge require­
ments.
Nature of surroundings and possible by­
passes.
Troops and equipment available.
Materials available.
Time required for bridge repair versus
time required to detour or construct by­
pass.
Standard tactical bridging units are gen­
erally well suited to emergency repair of
damaged existing bridges. However, it is
9­1
not within the scope of this lesson to go into
the use of standard bridging materials. TM
5­312 includes methods for repair of dam­
aged bridges using standard bridging ma­
terials.
Following are listed some of the more com­
mon materials and methods used in repair of
damaged bridges:
Standard dressed lumber is a stock item
and therefore available under most circum­
stances. It is very flexible in use and can
be built up to carry any weight classification
desired.
Repair by means of log construction in­
volves more time and effort, but will provide
an effective repair job if accomplished prop­
erly. Native logs may be available when
other materials are not.
You may also use earth or rock fill to build
up damaged parts of most bridges, especially
over waterways of low velocity. Except in
extreme emergencies, provisions should be
made for the passage of any water that may
be dammed up by such a structure. If the
proper equipment and personnel are available,
this method may prove to be rapid, especially
where low structures are involved.
4. FORDS
The word ford, as applied to an expedient
stream crossing, is a shallow place in a stream
where troops can cross by wading or driving
vehicles (fig. 1).
9­2
The most important characteristics of a
good ford site are a slow current (not over
3 feet per second); an even, hard, and ten­
acious bottom; a stream not subject to rapid
flooding, and approaches which slope gently
and provide good traction for both vehicles
and foot troops.
Ford sites will rarely be found in such
condition that they can be used without im­
provement. If the stream bottom is not firm
or level enough, it may be built up with rock
or gravel, sandbags, mats, or other materials
which will not float. The approaches should
be stabilized so they will not become slippery
from rain, snow, or water dripping off vehi­
cles.
Approaches and ford edges should be
marked and one or more marking posts
should be gaged to indicate changes in water
depth. An increase in depth due to flash
floods may cause a ford to be unreliable.
Minimum requirements for military fords
are given in table 1.
5. DIPS
Dips are paved fords used for crossings of
wide shallow arroyos or washes in semiarid
regions subject to flash floods and in other
locations where the construction of a bridge
is impractical.
The pavement should be protected on
its upstream side by a cutoff wall, and
on its downstream side by an apron.
An apron may also be provided on the
upstream side to prevent erosion.
The pavement may be macadam, concrete,
or timber. The cutoff wall should extend 18
to 24 inches below the paved surface.
Riprapping, rubble masonry, concrete, tim­
bers, or logs may be used for the surfacing
of the aprons. Protection should be carried
well away from the roadway edges.
Culverts should be constructed to take
the normal flow of the stream.
In areas where the stream channel nor­
mally is dry, the dip should be con­
structed about 6 inches below the bed
of the channel. This procedure will mini­
mize scour, and the soil deposited during
flood time can be easily removed.
Alinement should be straight and the pave­
ment location should be shown by two mark­
ing posts at each end and by as many inter­
mediate posts as necessary. One or more of
the posts should be gaged to indicate the
depth of water during floods.
6. CULVERTED CAUSEWAYS
Causeways provide a dry crossing. Cor­
rugated metal pipe (fig. 2) or 55­gallon drums
are placed in the streambed on a cushion
9­3
layer of sand or sandbags. Additional sand­
bags are placed between successive rows of
culverts to keep them in place. Then, a layer
of sand or sandbags is added to prevent the
culvert from crushing. Finally, a surface
layer of gravel, sand or sandbags is placed to
form the roadway. The built­up crossing
should be rocked in on both the upstream and
downstream sides to prevent washing and
scouring.
7. SWIMMING AIDS
If you are unable to swim, almost anything
that floats can be used as an aid in crossing
a stream.
Two gas cans lashed together will support
about 60 pounds and provide a very service­
able set of water wings.
A quickly improvised swimming aid can be
made from your trousers.
First be sure they are wet, then knot
each leg and button the fly.
Next, grasp the waistband on each side
and swing the trousers over your head
from back to front bringing the waist­
band down hard on the water so as to
trap as much air as possible in each leg.
The trousers then will form water wings
(fig. 3). The length of time they will
remain serviceable depends upon the type
and condition of the trousers.
8. ICE CROSSINGS
Crossings can be made over bodies of water
in areas where the temperature has been
below freezing for sufficient time to form an
adequate thickness of ice.
Table 2 gives required thicknesses of ice
for several different loads. These loads apply
at the interior portions of the ice slab.
Ice conditions adjacent to the shore line
may be different due to the nature of the
bank and rising or lowering of the water
9­4
level due to tidal action or change in volume
of flow.
Section II. RAFTS
9. INTRODUCTION
Rafts provide a very flexible method for
expedient stream crossings. The following
will illustrate a number of methods of con­
structing light, expedient rafts and stream
crossing devices from materials normally on
hand or readily available.
Empty containers such as 55­gallon drums,
gasoline and water cans, ammunition boxes,
and inner tubes are suitable for providing sup­
port for rafts, and are normally available.
If tops or caps are available which can be
fastened down tightly, they become closed
type contains. Without the lid or top, they
are open type containers.
The closed type container will give its maxi­
mum support even when submerged, whereas
the open type gives no support when sub­
merged.
10. DETERMINING RAFT CAPACITY
When used as closed containers, a 55­gal­
lon drum will provide approximately 440
pounds of flotation support, and a five­gallon
gasoline or water can will provide approxi­
mately 30 pounds of flotation support.
Therefore, if a raft is made up of 55 gallon
drums or 5­gallon cans, it is only necessary
to multiply the number of containers by the
support capacity of the types container used,
to get an approximation of the raft capacity.
If ammunition boxes or other containers
are used, it is first necessary to determine the
volume of the container in cubic feet, then
9­5
multiply that figure by 60. The capacity of
such a raft can be found by using the follow­
ing formula:
Capacity (lb) = (60 x container volume
in cu ft x number of containers) ­
(weight of raft in lb)
Example 1. A raft is constructed using six
containers, each having a capacity of two
cubic feet. The total weight of the raft is
300 pounds. What is the capacity of the raft
in pounds?
Solution: Apply the formula given above:
Capacity (lb) = (60 x 6 x 2) ­
300 = 720 ­ 300 = 420 lb
11. USE OF 55­GALLON DRUMS
Fifty­five gallon drums may be bound to­
gether to form a raft to carry personnel and/
or equipment across a water gap. Planks or
logs could serve as a decking for this raft.
The drum can also be lashed to the sides of
light vehicles and used as a floating support
to transport vehicles across a stream (figs.
4 and 5).
12. USE OF GASOLINE OR WATER CANS
Empty gas or water cans can be used as
an effective light raft. Six gas cans lashed
together will provide a serviceable light raft
to transport personnel and equipment.
The equipment may be placed on top of
the raft, with men holding onto the raft with
one hand and paddling with the other to
propel the raft across the stream (fig. 6).
9­6
13. PERSONNEL RAFTS
A float to cross two riflemen's individual
equipment can be made by laying all the
equipment on two shelter halves placed one
on the top of the other. The rifles with scab­
barded bayonets fixed should be crossed and
placed on top of the equipment. The outer
shelter half corners should be fastened to
the scabbards and butts by tent rope. A light
machine gun can be crossed in the same
manner by using shelter tent poles instead
of rifles.
The Australian poncho raft can be built
very rapidly from individual equipment of
two men. When completed the raft is cap­
able of supporting an 80 pound load.
Construction is started by taking the draw­
string from a poncho, twisting the hood and
tying it into a gooseneck . Then lay one
poncho out on the ground.
Place weapons (or sticks if you want to
keep the weapons out) about 18 inches
apart and centered on the poncho with
the barrels going in opposite directions
(the barrel should be covered with a
pair of socks) and the receiver down and
toward the inside. Place combat packs
on each end between the rifles, with hel­
met and liner on top of the pack. Cloth­
ing, boots, canteens, etc., are then placed
between the two packs.
Bring the sides of the poncho up and
snap all snaps. Start rolling a tight roll
until poncho is wrapped tightly around
equipment. Take each end of poncho,
twist them tight, bring the two ends up
over the top and tie them together using
a boot lace. Lay out the second poncho
and repeat the procedure used in the
first roll.
Next, take the two remaining boot laces
and tie them around the center of the
raft to give it more stability (fig. 7).
9­7
This raft will allow one swimmer to
transport two swimmers, or two non­
swimmers may cross a stream by joining
arms over the raft and paddling with the
free hand.
A machine gun can be placed inside a
single raft and floated with negligible
wetting. A mortar squad of five men
can, with its individual equipment, float
the 81 mm mortar and allied equipment.
Two rafts are constructed from the equip­
ment of four men. The fifth man can build a
raft using his own equipment or can distrib­
ute his equipment within the other rafts.
Brush rafts can be made by binding brush
into bundles about 18 inches in diameter and
placing the bundles on canvas. The sides and
ends of the canvas are wrapped over the
bundles and secured with rope (fig. 8).
Four infantrymen with equipment can be
carried on a brush raft using a 1/2­ton truck
cover tarpaulin, forming a bundle 5' x 6 1/2'
x 1'.
Six infantrymen and equipment can be car­
ried by using a 1 1/2­ton truck cover tarpaulin,
forming a bundle 6' x 9' x 1 1/2', and up to
3,000 pounds can be carried by using a 2 1/2­
ton truck cover, forming a bundle 8' x 9' x
1 1/2'.
14. VEHICLE RAFTS
A 1/4­ton truck can be crossed by using the
2 1/2­ton truck cover.
The truck is driven onto the cover at the
water's edge; the front and rear edges
of the cover are raised and fastened to
the truck. The sides of the cover are
then raised and draw ropes are tight­
ened around the truck. The truck is
then slid into the water.
Propulsion can be obtained by towing, pol­
ing, paddling or pushing. When there is a
noticeable current, a frame made from sap­
lings and placed at the base of the vehicle
will provide better balance and should be
used. Failure to do this may cause the
vehicle to roll over (fig. 9).
The 20 x 40 foot canvas tarpaulin will float
a loaded 1/2­ton or 3/4­ton weapons carrier, an
unloaded 1 1/2­ton or a 2 1/2­ton truck. This
raft as with all canvas rafts should be used
only on a site that is free of stumps, rocks,
roots, etc., and where the water is deep
enough to float the vehicle.
Empty vehicles usually float with the
water line just below the top of the
fender.
The canvas tarpaulin is spread at the
water's edge and then dragged over the water,
leaving a few feet around the tarpaulin to
hold the edges clear of the water. With the
front drive disengaged the truck is driven
onto the tarpaulin. The tarpaulin is then
folded and fastened to the vehicle. The truck
is then pushed out until it floats.
Propulsion is provided by towing, pushing,
or paddling.
15. LOG RAFT
Log rafts can be constructed with or with­
out the use of rope or wire lashing. When
lashing is used rather than notching much
time can be saved.
Dry logs of any type will make a service­
able raft. Bamboo also makes a fine raft,
especially when there is no rope or other lash­
ing available to bind the raft. The only tools
required are an axe and knife.
A raft 6' x 12' is considered suitable for
three men.
9­8
Build the raft on two skid logs placed so
they slope downward to the bank. Smooth
the logs with an axe so the raft logs lay
evenly on them. Cut four offset, inverted
notches; one on the top and bottom of both
ends of each log. Make notches broader at
the base than at the outer edge of the log.
To bind the raft together, drive through
each notch a three­sided, wooden cross­
piece about a foot longer than the width
of the raft.
Connect all the notches on one side of
the raft before connecting those on the
other. Lashing of the overhanging ends
of the two crosspieces together at each
end of the raft will give it additional
strength.
When the raft enters the water, the
crosspieces swell and bind the logs to­
gether tightly. If the crosspieces fit
too loosely, wedge them with thin pieces
of dried wood. These swell when wet,
tightening and strengthening the cross­
pieces.
If rope, wire, or other lashing is available,
the logs can be lashed without notching, re­
sulting in much greater speed in construction
of the raft (fig. 10).
9­9
Section III. CABLEWAY AND ROPE WALKWAY
16. CABLEWAY
A simple cableway (fig. 11) is easy to con­
struct and materials required are generally
on hand of locally available.
A hasty, field method for determining cable
capacity for fiber rope cable is by use of
the formula T = Dý. For wire rope cable
the formula is T = 8 Dý. In both cases: T =
safe working stress in tons, D = diameter
of rope in inches.
If either the fiber rope cable or the wire
rope cable are in doubtful condition the work­
ing capacity determined by above formulas
must be divided by two.
Example 2. Sufficient 3/4­inch diameter rope
(in doubtful condition) is available for use
in construction of a cableway. By use of
the hasty formula given above, what load
should this cableway carry safely?
9­10
Solution: T = D2
T = (3/4)2
T = 9/16 Ton
lbs
= 9/16 Ton = (2,000 ­­­)
Ton
T = 1125 lbs
Since the rope is in doubtful condition,
safe working capacity must be further re­
duced by dividing by 2. Therefore,
1125 ÷ 2 = 562.5 lbs
In many cases, wire rope is used instead
of fiber rope. The rule of thumb when de­
termining the safe working capacity of wire
rope is the formula T = 8Dý
Example 3. A 1/4" wire rope used in construc­
tion of a cableway can be expected to suc­
cessfully carry what load? The wire rope
is in doubtful condition.
Solution: T = 8D2
T = 8(1/4)2 = 8(1/16) = 1/2 Ton
T = 1/2 Ton = 1/2(2,000 lbs) =
1,000 lbs
However, the wire rope is in doubtful condi­
tion; therefore T is divided by 2. Safe work­
ing capacity equals 1,000 lbs. ö 2 = 500 lbs.
17. THREE­ROPE WALKWAY
A rapidly erected footbridge with a mini­
mum of materials may be constructed using
three fiber ropes (fig. 12) or wire rope cables
(fig. 13). The span should not exceed 150
feet as longer spans will be unstable when
loaded at midspan. Trees of at least 10­inch
diameter are required for anchorages for the
tread ropes, and 8­inch diameter for the hand
ropes. The fiber rope bridge is constructed
of 1­inch tread rope, 3/4­inch hand ropes and
1 1/2­inch suspenders. If wire rope is used,
3/8­inch diameter will be satisfactory. Sus­
penders for wire rope can be fabricated from
wire rope and cable clips or of 1­inch pipe
stanchions with cable clips at each end.
Erection procedures are as follows:
The length of the required span may be
determined by tying tape or a line across
the gap and allowing it to sag 5 percent.
The required length must be sufficiently
longer to allow for lashings to the an­
chorages.
The tread and hand ropes are laid out
as shown in figure 14. The ropes are
placed 3 feet apart. Suspender ropes,
cut 12 feet long, are placed at 2­pace
intervals. It stanchions are used, the
same interval is used.
The suspenders are attached to the tread
rope. A clove hitch is used in fiber rope.
The two ends of the suspender ropes pass
under the tread rope. Wire rope sus­
penders or pipe stanchions are attached
with wire rope clips.
The hand ropes are then raised elbow
high and the suspenders are attached.
For fiber rope, the suspender is tied to
the hand rope by a round turn and two
half hitches. Wire rope and stanchions
are attached with cable clips. All sus­
penders are attached in a similar man­
ner. Sufficient length must be left on
the tread and hand ropes to make the
ties to the anchorage.
The assembled bridge is carried to the
bridge site as shown in figure 15. The
lines are pulled across the gap and then
anchored on the far side with a bow­
line or a mooring knot. If a bowline is
used, an extra turn is taken around the
anchorage. The running end is tied back
to the standing part with several half
hitches. The wire rope is secured with
the cable clips after passing around the
anchorages. When all ropes are an­
chored on the far side, the tread rope is
adjusted to the proper sag and secured.
The hand ropes are then pulled tight and
secured.
When the bridge is complete, it is tested
to insure that all knots and ties are prop­
erly made and suspenders are adjusted.
Frequent inspection, adjustment of ties,
or tightening of bolts is necessary.
9­11
9­12
EXERCISES
First requirement. Multiple­choice exer­
cises 1 through 4 provide an opportunity for
you to show your understanding of the pre­
liminary considerations involved in expedient
stream crossings.
1. An expedient method for cross­
ing a stream is generally considered be­
cause of a pressing requirement. What
factor normally determines the urgency
of a stream crossings.
a. weather forecast
b. tactical situation
c. stream velocity
d. approaching darkness
2. Your engineer unit is on an
urgent tactical vehicular movement.
Upon arriving at a large stream, you
find that the bridge has been damaged
and is not passable. What is your first
consideration in deciding upon your
next move?
a. await construction of another
bridge
b. return to site of march origin
c. investigate the possibility of a de­
tour
d. commence crossing by use of rafts
3. The advance of an urgent tac­
tical vehicular column is halted by a
slightly damaged bridge across a wide
stream. There is no feasible detour.
What would you consider doing under
this circumstance?
a. possibility of making emergency re­
pairs to the bridge
b. request a change in march destina­
tion
c. await construction of a new bridge
d. abandon equipment and cross per­
sonnel only
9­13
4. The damaged bridge is a low
structure, and the waterway is of low
velocity. What action would you take
to make the bridge passable with the
minimum of delay?
a. requisition finished lumber
b. search for adequate standing tim­
ber
c. await construction of a new bridge
d. use earth or rock fill to build up
damaged part
Second requirement. Multiple­choice exer­
cises 5 through 12 are designed to enable
you to demonstrate your knowledge in the
construction of fords, dips, and causeways.
5. One of the most expeditious
means of crossing a stream is by a ford.
Which of the following reflects one of
the most desirable features of a good
ford site?
a. an even, hard, and tenacious bottom
b. a stream of clear water
e. steep uniform approach banks
d. protection from enemy observation
6. Approaches to fords normally
receive some surface treatment such as
gravel, metal matting or brush. What
is the purpose of this treatment?
a. so they will not become slippery
from rain, snow, or water dripping
off vehicles
b. to mark the approach to the ford
so that all traffic will be channelized
c. to improve the riding quality and
thereby reduce vehicle maintenance
requirements
d. to prevent erosion in the event of
heavy rainfall
7. You are to construct a ford
which will be used by infantry troops,
trucks, and medium tanks. What is the
maximum depth (feet) of water allow­
able?
a. 1 c. 3 1/2
b. 2 d. 4
8. You are building a ford to be
used by the infantry troops. What is
the maximum allowable slope?
a. 1:1 c. 3:1
b. 2:1 d. 4:1
9. Dips are paved fords used for
crossing wide, shallow arroyos or
washes in semiarid regions. Why would
you construct an apron on the upstream
side?
a. to control water flow
b. to increase traffic safety
c. to prevent erosion
d. to strengthen pavement
10. An arroyo is a watercarved gul­
ley or channel, much of which is dry
except following heavy rain or thawing
conditions. In areas where the channel
is normally dry, at what elevation would
you construct the dip?
a. at the channel bed level
b. at level to expedite construction
c. six inches above the channel bed
d. six inches below the bed of the
channel
11. There is one major difference
between a causeway and a ford or dip.
What is this difference?
a. causeways are normally longer
b. causeways are easier to construct
c. causeways require less maintenance
d. causeways provide a dry crossing
12. You are constructing a cul­
verted causeway, and are placing sand­
bags between successive rows of
9­14
culverts. What is the purpose for these
sandbags?
a. to prevent crushing of culvert
b. to keep culverts in place
c. to prevent seepage of water
d. to provide smoother riding condi­
tions
Third requirement. Multiple­choice exer­
cises 13 and 14 deal with considerations in­
volved in ice crossings.
13. When you consider an ice cross­
ing, the thickness of the ice at an in­
terior portion of the slab must be de­
termined. What other condition must
you investigate before initiating a cross­ ing? a. long­range weather forecast
b. ice conditions adjacent to the shore
line
c. velocity of stream flow
d. temperature at time of crossing
14. Ice thickness for general de­
termination of load carrying capacity is
measured at an interior portion of the
ice slab. What ice thickness in inches
should you have existing before con­
sidering crossing 2 1/2­ton trucks with
light loads?
a. 4 c. 8
b. 6 d. 10 Fourth requirement. Multiple­choice exer­
cises 15 through 18 are designed to insure
an understanding of some of the more com­
mon improvised rafts that may be used in
expedient river crossings.
15. A closed type container is one
which will not permit entrance of water
even when completely submerged. An
open type container allows water to en­
ter when the opening is below the water
line. What is the greatest advantage in
the closed type container?
a. is more resistant to being deformed
b. gives maximum support even when
submerged
c. requires less time to construct the
raft
d. is more readily available than open
type
16. Empty fifty­five gallon drums
may be used to construct rafts for per­
sonnel and equipment. A load of equip­
ment, personnel and the decking and
lashing required is estimated at 4,200
pounds. How many 55­gallon drums
do you need to provide the necessary
buoyancy?
a. 10 c. 14
b. 12 d. 16
17. An empty 5­gallon gas can will
provide flotation for approximately 30
pounds. How many gas cans do you
need to support a soldier weighing 200
pounds? The timbers and lashing in­
volved weigh 30 pounds.
a. 4 c. 8
b. 6 d. 10
18. Truck covers and tarps can be
used to float vehicles across a stream.
A cover from which of the following
truck bodies would you use to float a
1/4­ton truck?
a. 1/4 c. 1 1/2 T
b. 3/4 d. 2 1/2 T
Fifth requirement. Solve multiple­choice
exercises 19 and 20 to insure that you have
an understanding of the use of cableways and
rope walkways in expedient stream crossings.
19. A one inch fiber rope in doubtful
condition is the only rope available for
a cableway. Using the hasty calculating
method, what load in pounds can you
expect the rope to carry?
a. 250 c. 750
b. 500 d. 1000
9­15
20. You are constructing a three­
rope personnel bridge. It is easily and
rapidly constructed from either wire or
fiber rope. What is the maximum rec­
ommended length in feet for this type
bridge?
a. 100 c. 150
b. 125 d. 175