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M 114ka AND APP‘UCAW

OF SURFACE EARTH MOVING
EQUIPMENT

Thai: for tho Doom of I, I.
MICHKEAN STATE COLLEGE
Richard C. Wave:
1948.

THESIS

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The Theory and Application of Surface
Earth moving Equipment
A Thesis Submitted to

The Faculty of
MICHIGAN STATE COLLEGE
of

AGRICULTURE AND APPLIED source
by

Richard C. Never

Candidate for the Degree of

Bachelor of Science

December lQhB

THESIS

Ll

1/20 (”l

‘f

AC KN O HYLL‘D Gfl‘a‘hfil‘é

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The author is indebted to Professor

C. L. Allen, head of the Civil
Engineering Jepartment, to Mr. Conner,
instructor in the Civil Engineering
Department, and to the many others

who have been of great assistance.

‘

238723 9 vi)

TABLE OF CONTENTS

INTRODUCTIOY
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EART I: The Tneory of Surface earth MOVing equipment

Power Shovels 1d Cranes - - - - - - - - - - - - - l

Tractors - - - - - ~ - - - - - ~ — _ _ - - - - - _ 19

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Tractor Mounted Equipment

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Tractor Drawn Equipment -
Motor Graders and Motor Patrols- - - — - - - - - - 37
Bucket Loaders - - - - - - - - - - - - - - - - - - LO
Long Range Earth Movinq Equipment - - - - - - - - hl
Trenchers - - - - - - - - - - - — - - - - - — — — h?

Trucks - - — - - - - - - - - - - - - - - - - - - - SO

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Equipment Transportation

PART II: The Application of Surface Earth Moving I uipment

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Power Shovels and Cranes -
Tractors - - - - - - - - - - - - - - - - - - - - - 75

Tractor Mounted Equipment

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Tractor Drawn Equipment
Motor Graders and Patrol Graders - - - - - - - - - 8h

Bucket Loaders - - - - - - - - - - - - - - - - - - 85

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Long Range Earth Moving Equipment
Trenchers - - - - - - - - — — — - _ - - - - - _ _ 90
Trucks - - - - - - — - - - — - _ - - - - _ _ - _ _ 93

Blasting Equipment - - - - - - - - - - - - - - - - 9h

LIST OF ILLUSTfiATIONS

page
Shovel Bed Plate Assembly - ~ - - - - - - - - - - - - - 3
Shovel Crawler Mounting - - — - - - - - - - - - - - - - 6
Shovel Truck Mounting - - - - - - - - - - - - - - - - - 9

Shovel Eront End mquipment - - - - - - - - - - - - - - 16

fiubber Mounted Tractors

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Tractor Drawn Scraper - - - - - - - - - - - ~.- - - - - 32
Euclid Loader - - - - - - - - - - - - - - - - - - - - - 36
Motor Grader - - - - - - - - - - - - - - - - - - - - - 39

Bucket Loader - - - - - - - - - - - - - - - - - - - - - 39

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Conveyor Type Trencher

Euclid Dump Truck - - - - - - - - - - - - - - - - - - - 51

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Shovel Stripping Coal —
Trench Hoe Excavating for Sewer - - - - - ~ - - - - - - 00

Shovel Excavating hock - - - — - — - - - - - - _ - - _ 00

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Shovel Excavating Soft marth -

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Table on Shovel Dipper Capacity

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Shovel Swing and Digging Depth Chart
Table on Dragline Capacity - - - - - - - - - - - - - - 7h

Dragline Swing and Digging Depth Chart

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Tractor Drawn and Tractor Mounted Equipment - - - - - - 80

Slackline Cableway in Open Pit Mining - - - - - - - - - 87
Slackline Cablquy Excavating Gravel - - - - - - - - - do

Long Span Slackline Cableway - - - - - - - - - - - - - 69

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Trencher biasinv Throuah Semi-solid hock

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INTRODUCTION

Man has always been surrounded by great resources,
but it is only to the extent that he could use these
resources that they have been of value to him. The
first great step in the utilization of these resources
was the application of simple hand tools to his every-
day necessities. Today, complex and powerful machines
roar across the face of the earth building roads,
moving mountains, digging great holes and turning the
centuries old courses of rivers.

Machinery has not yet reached its maximum development
but it has reached a point where the degree of intelligent
application of tools, detailed efficiency in their use
and continued striving for higher production are the
fundamental considerations deciding the extent to which
a user is successful.

Although fundamental in scope, it is hoped that the
material in this thesis will_create interest and under-
standing in the theory and application of surface earth

moving machines.

POWER SHthLS AhD CRANES

To properly discuss the theory of the design of a
piece of equipment one should have at least some know-
ledge of the basic operations of the machine. In the case
of power shovels and cranes, the four basic operations may
be summed up as follows: (1) crowding, the forcing of the
dipper into the earth, (2) hoisting, the pulling of the
dipper through the earth and lifting of it above the digging
level, (3) swinging the horizontal transfer of the dipper
from one point to another, (A) traveling, the moving of the
machine from one place to another. These four basic oper-
ations apply to all power shovels and cranes, but there are
many ways of accomplishing them.

To start on a discussion of the machines themselves it
would probably be best to divide them into their major com-
ponents. The first major component to be taken into consid-
eration is the revolving superstructure. The revolving
superstructure is a platform on which are mounted the engine
and the mechanism which permits hoistinfi and swinging as well
as the transmission of travel power. The superstructure as
a whole is made up of the following elements.

(1) The bed plate is the foundation on which is mounted

all of the Operating mechanism. This plate may be of cast

steel or welded construction. Boom hinge brackets are pro-
vided at the front end of the bed plate for attaching the
front end operating equipment.

(2) On the bed plate is erected the A Frame and machinery
frame.

The A Frame consists of a triangular structure made up
of the bed plate, a vertical member, and slanting front struts.
The A Frame provides an elevated position for the boom der-

1’1

ricking lead sheaves and cables which support the boom equip-
ment. It also helps absorb the stresses of the boom pull.

The machinery Frame furnishes the means of attaching the
power shafting, the operating equipment, etc.

(3) The power equipment may be gasoline, Diesel or elec-
tric. These internal combustion engines are of the high
torque, industrial type with speeds of 800 to 1800 R.P.M.

Any standard commercial type of electric motor may be used.

(h) The power take off and transmission furnishes the
means whereby the power from the power equipment may be
transmitted to the operating equipment. The first step is a
power take off which.may be through a plate disc clutch or a
hydraulic coupling. Tie power then goes through a speed re-
duction assembly consisting of a train of gears, a chain drive
or a combination of the two.

To further explain the operations of the revolving super-
structure the Operation of the equipment m unted on the bed

plate should be explained. The boom on any machine may be

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Typical arrangement of power plant,

A frame, and power take-off on a shovel bed plate

raised or lowered through an arc, pivoting about its point
of attachment at the front of the bed plate. This is know
as boom derricking or lowering, and a boom hoist or derrick-
ing device must be installed on the revolving superstructure.

The hoisting mechanism provides a method of lifting or
lowerin; loads in a vertical plane. The hoisting mechanis
usually consists of two drums vhich may be mounted side by
side on one shaft or on two shafts in tandem.

Each hoist drum is controlled independently by a clutch
and a brake. The controls actuating the clutches may be
straight mechanical, mechanical w’th booster clutches, hydrau-
lic air or vacuum. Usual lifting operations may require only
one drum which is called the Rain Poist. However two drums
are provided to accommodate clamshell and dragline service ~
and the second drum is called the Secondary Hoist drum.

The entire superstructure or turntable may be revolved
through 3ao degrees in either direction. This is accomplish-
ed through the swing mechanism. The swing mechanism consists
of a vertical swing shaft and the proper mechanism and swing
clutches on the superstructure so that the vertical shaft
and consequently the superstructure may be rotated in either
direction.

The power mechanism and control clutches for propelling
the traveling crawler or wheel mountings are provided by the
travel mechanism on the superstructure.

The transference of the propelling power from the super-

structure into the mounting requires a vertical travel shaft

much like the swing shaft. This shaft is located at the axis
or center of rotation of the superstructure. Through suit-
able clutches the operator may select the prOper direction of
rotation for forward or reverse travel.

The second major component of the shovel is the mount-
ing. There are three types of mountings: crawler mountings,
truck mountings, and wheel mountings.

In general, crawler mountings are those of the track
laying type with two parallel continuous crawler or tread
belts. The crawler mounting consists of four primary parts
as follows.

(1) The crawler car body which transfers the revolving
superstructure and weight into the crawler frame. It also
houses the vertical and horizontal propelling shafts, and
the clutches or brakes which control crawler steering.

(2) The crawler frame, on which the crawler car body
rests and is secured, includes the side frames, rollers, and
final end drive mechanism. The crawler frame serves the
further purpose of distributing the weight loads over a much
greater area.

(3) The crawler tread consists of tread shoes or links
which are pin hinged together in a continuous belt and which
fit around the side frames. The length and width of the
tread belt provides considerable ground bearing area which
gives further weight distribution resulting in the low ground

pressure that enables the crawler mounting to overcome many

 

Shovel crawler mounting with one track removed

soft-ground conditions.

(h) The power flow or final drive to the crawler tread
belts may be chains or gears. Either method transmits the
propelling unit along the ground, Crawler mounting speeds
usually range from 1/2 to 2 miles per hour and one or more
travel speeds may be available.

In addition to the crawler mountings just discussed,
the revolving superstructures or turntables of power shovels
and cranes may be mounted on rubber tired mountingsof which
there are two main classifications: truck mountingsand wheel
mountings

Truck mountingsmay be heavy duty commercial motor-trucks,
'reinforced and modified as necessary for the mounting of
shovels and cranes, or they may be chassis specially designed
by crane manufactures for this purpose. Generally the
chassis is called a carrier.

Such units of either type are known as two-engine truck
mountings because a separate and second engine is provided
to propel the mounting on which the turntable is mounted.
There is also a design in which the carrier engine is used
to drive the mechanism on the superstructure.

Truck mountings may be supported by two or three axles
and the method of driving the carrier wheels may be chain
or gear drive. Drives are designated by standard automotive

nomenclature as follows: (1) two axles with rear axle driven

is hXZ, (2) two axles with front and rear axles driven is hxh,

C3

(3) three axles with the two rear axles driven is 6x4,
(A) three axles with three axles driven is 6x . In other
words the first number in the designation is the total number
of wheels, and the second number in the designation is the
number of driven wheels.

Two engine truck mountings usually have a range of
four to ten Speeds forward and two speeds reverse. The top
speed of the above truck mountings is usually about 30 miles
per hour.

Wheel mounting, that is, single engine mountings are
also rubber tired mountings. They differ from the truck
mountings just discussed in that they have only one engine
for powering both the superstructure equipment and.to propel
the carrier. This engine is mounted on the superstructure.
Different mountinfis are described as 6x6, éxh, hxh, hx2,
following the same manner of designation as described for
truck mountings.

Wheel mountings require a specially designed chassis.
Also all controls for steering, brakinfi, gear shifting, etc.
are located in the operator's cab.

Wheel mountings also differ from truck mountings in that
they usually afford a range of one to four speeds with a top
speed of approximately ten to twenty miles per hour.

In addition to the types of mountings alread} discussed
there are several types of special mountings vhich are
designed to do a specific type of job. Three of these special

mountings are (l) the pier or stationary mountings, (2) the

 

Truck mounting featuring a Ll. x 6 type drive '

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portal or gantry mounting which is a high structual steel
mounting that travels on rails, (3) barge mountings.

The nex major component of the power shovel to be dis-
cussed is the front end Operating equipment. There are five
basic types of front ends which are interchangeable. They
are the shovel, crane, clamshell, dragline, and back hoe.

Since the shovel boom is probably the most fundamental
and most widely used type of front end it will be described

first.

Shovel boom eouipment include the shovel, the boom

(3

eroper, the dipper stick and the dipper ~tick trip mechanisu.
In addition it includes some mechanism on the superstructure
for crowding and retracting the dipper stick.
The dipper stick is mounted about halfway up the boom
on the shipper shaft, and slides back and forth relative
to the boom. The front end of the stick, carrying the
dipper, may be raised or lowered as the stick may be pivoted
about the shipper shaft at any point along the length of the
stick.
The operations involved in shovel work are:
(l) The hoisting Operation by which the dipper
is pulled through the material being dug.
(2) The crowding operation by which the dipper
is thrust or forced through the material
being dug.
(3) The retracting Operation by which the dipper

is withdrawn or pulled out of the material

11

being dug.

(h) Hoisting and crowding are usually employed
simultaneously in the digging cycle to
force the dipper into the material at the
same time it is being pulled through the
material.

Except when an individual electric motor is used, power
for crowding and retracting is transmitted from the super-
structure to the boom by a system of chains or cables or a
combination of the two. In order to give a clearer picture
of the three main types of crowding mechanisms a more de-
tailed explanation is necessary. The first type, the inde-
pendent or positive chain crowd requires the use of only one
drum on the superstructure. This is the hoist drum which
controls the hoist cable used to raise and lower the dipper.
This method does require that the superstructure be ecuipped
with a separate crowd shaft or some type of reversable shaft
which may be rotated in either direction so it can actuate
the chain drive in either direction. The chain crowd drive
extends from the crowd shaft or reversing mechanism on the
superstructure to the boom foot and then up the boom to the
shipper shaft. Thus by controlling the direction of the crowd
shaft on the superstructure, the shipper shaft pinion may be
rotated in either direction so that the dipper stick may be
crowded or retracted. In this design hoisting may be inde-
pendent of crowding or retracting, or may be used in combin-

ation with either crowding or retracting.

12

In this type of crowd, power is transmitted from the
shipper shaft to the dipper stick, and thus to the dipper,
by a rack and pinion drive which consists of a geared pinion
on the shipper shaft vhich meshes with a rack or flat gear
on the dipper stick.

The second type of crowd mechanism is the independent
or positive cable crowd. The characteristics of this me-
chanism are very similar to those of the chain crowd. In
this design, however, cables replace the chains, and two cabka
drums are reduired on the superstructure. One of the drums
is used to hoist the dipper by means of the hoist cable.
The other drum is reversible and is used to operate the crowd
and retract cables. The drum to which the separate crowd
and retract cables are attached must be reversible so as to
provide for the pull of the cables in either direction to

effect crowding or retracting the dipper. In this case when

the crowd cable is wound on the drum, it crowds or forces
out the dipper stick. When the drum is reversed the retract
cable is wound on the drum thereby causing the dipper stick
to retract.

Since, in this type of crowd, the power is usually
applied by cables to the ends of the dipper stick, it is only
necessary to provide a guide or sleeve at the shipper shaft
through which the stick slides freely in either direction.

his sleeve is mounted on and pivots about the shipper shaft.

A third ype of crowd mechanism is the combination

13

cable crowd which differs from the previous two types in
that (1) it uses both hoist drums on the superstructure but
does not require any reversing drum or mechanism and (2) the
crowding motion may only be effected automatically and
simultaneously with hoisting operations. As the combination
hoist and crowd cable is wound on the drum, the dipper is
hoisted, and because the front end of this cable is brought
down and dead ended on the rear of the dipper stick, the
stick is simultaneously forced out or crowded. This design
permits straight hoisting, without crowding, but crowding
can never be effected without hoisting.

The retract cable is attached to the second drum, with
the front end of the cable dead ended at the dipper end of
the dipper stick. Thus as this cable is wound about th
drum it will pull back or retract the dipper stick.

This type of crowd may be used with either the rack and
pinion drive at the shipper shaft, or if the cables are
uidin~ sleeve

5..)

attached to the ends of the dipper stick, the 3
may be used.

Other types of crowds include (1) a combination of the
independent cable and the independent chain crowd; (2) a
dual crowd which combines both the independent cable crowd
and the combination cable or wd and (3) the use of individual
electric motors to drive each operation.

Another type of front end equipment is the lifting

crane. Lifting cranes are primarily units for lifting an

lb.

object, transferring the object to a new location by swing-
ing of the superstructure or traveling the entire unit, then
lowering or placing the object in its new location.

Though the lifting crane boom is not used for excavation
by itself, it will be described here since it is a part of
dragline and clamshell equipment.

Basic lifting crane equipment consists of a common
crane boom, hoist drum lagging for the desired line speeds
and pulls, and a hook block to provide the required parts of
line for the lifting service specified.

The common crane boom is usually made in two sections
separable at the center into upper and lower sections,
with a boom head and a system of Sheaves located at the upper
end of the upper section.

The crane boom upper and lower sections may be fastened
together by three methods: (1) by pin and clevis connections;
(2) by splice plates: (3) by bolted flange plates.

The standard lengths of the common crane boom will often
not be sufficient for the job to be done. There are, there-
fore, two methods by Which the length of the boom may be
increased to increase the working ranges and reaches.

One of these is the use of a boom extension or jib.
This consists of an extension which can be added to the head
Of the boom and is usually added for steel erecting or

single line work. Boom tip extensions may be used as

straight extensions, that is as straight extensions of the

boom, or may be used as gooseneck extensions in which case
they are offset from the center-line of the boom.

The second method of lengthening the boom is by the
insertion of intermediate center sections between the top
and lower sections of the boom proper. Usually intermediate
center sections may be used in multiples up to any maximum
boom length Specified by the manufacturer. The method of
connecting center sections is by the same method of connec-
tion as used on the common crane boom.

When booms are lengthened to a certain point, some
manufacturers require the installation of a gantry or high
APFTame. This is simply an extension added to the standard
A-Frame to elevate the derricking lead Sheaves.

One type of front end equipment of a specialized nature
is the clamshell. The name "clamshell" is derived from the
general shape and operation of the bucket used on this machine.
In general, the clamshell buckets consists of two halves or
shells, hinged together at the top so that the bucket can be
opened, or so that the two can be drawn together to form a
sort of bowl-like arrangement. At the start of the digging
cycle the bucket rests on the material with the shell open.
As the hoist or closing line is wound up on the drum, the
two halves of the bucket come together, digging their way
through the material and filling the bucket as they come to-
gether. While the bucket is closing the weight of the bucket

helps bite into and penetrate the material being dug. This

16

is the only "crowding" action available with a clamshell.

Clamshells consists of a common crane boom, a tagline,
hoist drum leggings for the proper line pulls and speeds,
and a clamshell bucket and proper cables.

The tagline is a small cable under tension which keeps
the bucket from spinning, swaying, twisting, or drifting.

Both hoist drums are used for clamshell work, one for
the cable which (1) closes the bucket when it is digging
into the material and (2) then hoists it to dumping height.
This is known as the closing line which is reeved in the
bucket. The cable from the other drum is fastened to the
top of the bucket, and serves to hold the bucket suspended
when dumping. This is known as the holding line. Dumping
is effected by releasinr the closing line.

The fourth common type of front equipment is the drag-
line. The dragline derives its name from the dragline
bucket. The dragline bucket may be described as a bucket
which is tossed away from the machine onto the material and
is then dragged toward the machine, filling the bucket with
material as it is dragged in and pulled through the material.

Dragline equipment consists of a standard common crane
boom, the fairhead, hoist drum laggings for proper line
pulls and speeds, dragline bucket, and proper cables.

The fairhead is a device of sheaves or rollers, the

purpose of which is to guide the drag cable from the bucket

to the drag drum. The fairhead is located usually near the

17

foot of the crane boom.

The dragline unit requires the use of both hoist drums.
One cable goes over the head of the boom and is used to raise
and lower the bucket. The other cable is the d agline cable
and runs from the secondary hoist drum through the fairhead
and to the bucket. It is used to pull the bucket in through
the material during the digging operation and releases it
for dumping after it has been raised to the proper position.

The fifth type of front end equipment is the back-hoe.
This equipment is so named becaase its digging action re-
sembles that of the garden hoe in that the dipper is on an
arm which is pulled toward the machine.

The hoe consists of a boom with a dipper stick pivoted
at the end of the boom, a dipper attached to the lower end of
the dipper stick, proper drum laggings and a mast or A-Frame
that is located at or near the boom hinges to provide proper
hoist cable leads.

In operation, (1) the boom, with dipper arm extended,
is lowered into the excavation: (2) then the dipper is pulled
or dragged toward the machine with the drag cable; (3) when
the dipper is filled, the entire boom assembly is raised by
the hoist cable; and (h) the load is dumped by extending
the dipper stick. If you will think of your hand as the
dipper, your forearm as the dipper stick, and your upper arm
as the boom, and remember how you used to dig holes on the

beach, you'll have a good idea of how the hoe works.

18

 

 

 

ypes of

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Examples of the basic t

front-end equipment

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TRACTORS

The type of tractor most widely used in earthmoving
is the crawler tractor. The crawler tractor is primarily
the result of a need for a machine to tow, push, pull,
power or mount construction equipment. It is designed to
withstand the abuse and rough handling encountered on jobs
where it is used. It is a basic "pioneer" tool of construc-
tion work and it serves as a prime mover for pulling and
pushing loads, power for winches and hoists, and a moving
mount for side booms, bulldozer blades, and front end
buckets. Its main distinguishing feature, the crawler tracks,
are used because they give the maximum tractive effort for
the soil and ground conditions in which they operate, and
because the length and width of the tracks bridge many ruts
and ground irregularities.

The crawler tracks are made up of connected rigid
steel plates. The plates, or track shoes as they are called,
are of varying design, depending on the use to which they
are put. The characteristic ridge on the shoe which digs
into the ground for gripping action is called the grouser.
The grouser varies in height from 2 l/h" to 2 3/h" depend-

ing on the tractor size. Semi-grousers are so called

because their height is approximately 1/3 the height of the

20

standard grouser. They are used where good dig-in traction
is needed and the tractor work requires much pivoting with
little forward motion of the tractor. he reduced height
of the :rouser reduces the power needed and stresses set
up in turning. They also permit track slippage before ex-
cessive stress can be placed on the tractor or attached
ecuipmcnt. Semi-grousers are also used where a full grouser
would injure the surface on which the track is riding.

Track treads vary in width from 7” to 28”, depending
on the size of tractor, and the use to which it is to be
put. If a track is wide it gives reduceiground loading
per souare inch and improves flotation. If the track is
narrow, the ground pressure per square inch is greater and
in soft ground there is a tendency to sink in. Track slip-
page is a shearing action. On some soils such as a firm
clay loam, increasing the ground pressure per seuare inch
increases the density of the soil and decreases the tendency

of the so’l to shear. However, many soils such as a dry

H

powdery earth, do not compact well and to reduce track
slippage it is necessary to use a wide track vhich will
present more area to be sheared even though it reduces the
ground pressure. There is for each weight of tractor and

il conditions one track width

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use of tractor on given s
which best fits the operation. In general the ground pres-
sure in pounds per square inch of crawler tracks varies

approximately between 6.50 to 8.25. This is about equal to

21

the pressure per souare inch exerted by a man standing on
the ground. Tracks should not be wider than necessary to
effectively perform the job to be done. Because the track
is supported near its centerline, extreme widths increase
wear due to greater twisting action when the load is carried
on the side of the track. Extreme widths or lengths also
increase the difficulty of steering.

Track shoes are furnished with rubber surfaces, flat
metal surfaces and for use in ice and snow. They may also
be heat treated for extremely rough operation on hard sur-
faces such as rocks, or to reduce abrasion wear as in fine
mmdsmm.

Crawler tractors are usually steered by means of mul-
tiple disc clutches connecting the power to each track.
Disengaging the clutch stops the power to a track, and when
the tractor is pulling a load, causes the tractor to turn
in the direction of the track which has stopped.

When the tractor is being pushed by the load, as when
the tractor is going down grade with the engine braking the
load, disengaging a clutch causes the tractor to turn away
from that track. Sharpness of turning can be increased by
braking the track on the side in which it is desired to turn.

In addition to the two steering clutches, there is also
a master clutch similar to the clutch in a car which connects

the engine power to the transmission.

Speed control is done by means of a throttle lever.

22

Clutches are also actuated by hand levers instead of foot
pedals.

Tractors are rated by size and power. Size is im-
portant because, as an important rule of thumb, a tractor
with adequate power can exert on its drawbar a pull ecual
to approximately 90% of its weight. Pulls in excess of
this cause the tracks to slip.

The pull developed on the drawbar is usually expressed
in pounds or as drawbar horsepower. Engine horsepower is
also used as an index, however, because of various fric-
tional losses between the engine back to the tracks, the
engine horsepower will not indicate the pulls and speeds
available. Drawbar horsepower will also not indicate the
speed and pulls available.

Tractor balance is an important characteristic of

tractor design. If the tractor is heavy on one end, it

tends to die in at that end. Adding more length of track

\J

'I.

to offset this condition makes it more difficult to steer
and increases track wear. “urthermore some tractors have
fronsequipment, such as bulldozers, while others carry the
load on the rear, such as in scraper pulling.

Tnere is no perfect "all purpose" design, but rather
all designs are the result of compromises with what is
needed and tlat which is practical.

One of the most important recent developments in

crawler tractors is the application of the hydraulic torque

23

converter. This device installed between the master clutch
and the transmission serves two main purposes:

(1) As a device permitting the elimination of most

of the transmission years, and to increase or
decrease the toroue.

(2) As a fluid coupling between the engine and the

transmission.

The torque converter principle is not new, having been
used for years in hundreds of power installations such as
boats, trucks, and busses where a strong, smooth power flow
of rapid flexibility was needed.

As a prime mover the crawler tractor is superior to
rubber tired hauling units in its ability to travel rougher
terrain and exert stronger drawbar pull. The versatility
and the characteristics of the hydraulic torque converter
have increased the variety of the operations that a crawler
can perform and have improved the effectiveness with which
it can perform many of these operations.

Characterized by the fluid absorption of shock loads
and the impossibility of stalling the engine, this converter
enables the tractor to develop its maximum drawbar pull when
most needed. Automatically adjusting itself to the load,
the torque converter develops a greater and greater output
as the load on the.tractor is increased, making it no lo ger
necessary to slip the clutch to maintain eng‘ne speed as

with the all gear transmission.

The followinfi is a list of 5 me of the advantazes of
. - x.)

the torque converter over the all gear transmission.

(1)

(2)

(3)

(‘4)

(S)

(7)

The converter automatically develops in-
creased turning force on the tracks as the
tractor is loaded.

Drawbar pull is limited only by the traction
of the crawler tracks.

Eliminates the overloading of the engine
resulting when its speed is "lugged" down,

by permitting the engine to operate at a
speed range where it develops high torque

and horsepower.

The fluid in the converter absorbs shock
loads. This reduces tractor wear.

On soft footilfi, smooth speed and power flow
improves flotation by reducing jerking of the
tracks when the master clutch is engaged.
When the tractor is used to power a winch or
hoist it enables the development of high line
pull at low line speed. The engine can be
throttled so that the line Speeds are low, yet
the engine speed is kept sufficiently high so
that it doesn't "lug" down or stall.

When the tractor is used as a pusher tractor,
it tends to synchronize its speed and power

with the unit being pushed and results in a

steady, continuous pushini action.

A
)-.)
V

Greatly reduces the amount of gear shift-
ing done. This saves on clutch wear, re-
duces operator fatigue, and simplifies
tractor operation.

The most important trend in types of earthmoving
eduipment in recent years has been the application of
rubber tired equipment for both the tractor or power unit
and the units used with tractors. Like any equipment, it
has its advantages and disadvantages. ’In general it may
be said that on long hauls, over 1000 feet, the rubber
tired unit will haul more dirt at a lower cost than will a
crawler tractor. The hauling speeds of crawler tractors
are considerably less than the rubber tired tractors. With
this increase of speed in the rubber tired tractors there
is also a marked decrease in the pounds of pulling power.

The standard type of wheel tractor is made by several
manufacturers, some of the leading ones being International
Harvester Company and Minneapolis-Moline.

There are several manufacturers that make specialized
pulling tractors. These tractors have two large rubber
tired drive wheels and are used to pull scrapers and dump
wagons. They can not be used without the unit they are
designed to pull since the balance of the tractor depends
on the two drive wheels and the balancing weight of the
load. The steerinq of hese machines is much the same as

that of the crawler type tractor. In order to turn, less

power is applied to the wheel on the side of the turn,
thereby causing the other wheel to turn faster and push the
tractor toward the other side. The main difference in the
steering mechanism of the crawler type and the two wheeled
type of tractor is that the tracks on the crawlers are con-
trolled either by clutches or a power steering mechanism
while the two wheeled types are almost always steered by an
electrical or mechanical power steering mechanism. The two
main sellinr points of these two wheeled tractors are the
short turninfi radius and the increased Speed. The maximum
loaded speed of these units is about 16 miles per hour.

The latest development in heavy duty tractors is a
tractor manufactured by the Le Tourneau Co. It has four
large rubber tired driving wheels. The tractor is steered
in the same manner as a crawler type. One unique feature
of this tractor is that the operator sits in front of the
engine directly behind the blade. These tractors are made
in two sizes with diesel power plants of 180 to 300 horse-
power. The pulling power of these tractors comes m ch
closer to that of an equivalent sized crawler than any
other type of rubber tired pulling unit and still speeds
up to 16.3 miles per hour are obtainable. Maximum speed

can be obtained in both forward and reverse travel.

a..._.

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Four wheel rubber tired tractor

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Rubber tired "Tournadozer"tractor

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C13

TRACTOR MOUNTED EgUIPIEENT

The bulldozer is the traditional "work horse" of
earth moving equipment. No other one piece of eouipment
offers such a variety of loading, pushing, or lifting
operations and can apply these in so many different ways.

The "dozer family" consists of angledozers, tiltdozers,
pushdozers, dozecasters, and trailbuilders, which are var-
ious trade names for bulldozers which may be tilted, angled
out on one corner, or will permit one corner to drop lower
than the other for better penetration. or for side hill
cutting.

The bulldozer is basically a slightly curved pushing
blade mounted on the front of a tractor. It is attached to
the tractor by two long push beams, and may be raised or
lowered either hydraulically or by cable controls. Since
the bulldozer depends on more or less "brute strength" to
move the dirt or objects in front of it, it is made of
heavy gauge steel plate. The steel is usually heat-treated
to give it extra toughness.

For clearing land a special blade is used. It has ad-
justable teeth protruding from the bottom of the blade.
These teeth help dig up roots and large boulders.

One type of tractor equipment that is becoming very

29

popular is the "tractor shovel.” The tractor shovel con-
sists of either a crawler type or a wheel type tractor with

a hydraulically operated bucket mounted on the front end.

The bucket may be dumped at any height, quickly or slowly,

in part or all at once. The unit is ideally suited for
basement excavation, loading trucks, maintaining stock piles,
snow removal, and a multitude of miscellaneous jobs. Buckets
are most generally of 3/h, l, and 2 cubic yard capacity.

The 2 yard buckets are used for snow removal. For bull-

dozer work a quickly interchangeable bulldozer is available.

3o

TRACTOR-DRAWN EQUIPMENT

\
J

The tractor drawn scraper is designed to dig, load,
haul, dump, and Spread. The main parts of the scraper are
as follows:

(1) The bowl which holds the dirt. In some

scrapers the bowl is hinged and tips for-
ward to roll the dirt out.

(2) The apron, a curved wall in front of the
bowl which opens and closes to operate the
flow of dirt in and out of the bowl.

(3) In some scrapers, a tailgate, which is a
wall in the rear of the bowl used to push
the dirt out of the bowl.

(h) The cutting edge which is lowered into the
dirt to make a shallow cut.

These machines dig their own load during the forward
motion of the accompanying tractor. A cutting blade which
may be raised or lowered to maintain any digging depth down
to about 8 inches is pulled through'the earth and the dug
material travels up its face into a car°ying bowl, and falls
forward into a carrying apron. When the two are loaded the

apron is allowed to drop and enclose all of the loaded dirt.

31

The apron having closed, the entire bowl is then raised
away from the ground through a sheave and cable arrangement
to allow carrying the load to its resting place. Great
pneumatic tires cushion the shock to reduce hauling work.
At the fill, dropping the cutting edge to a desired height
above the ground, the blade forms a strike-off control
under which all of the load is spread.

The front apron opens first, dumping its load on the
ground in front of the blade. Forward motion of the tractor
allows all dumped dirt to roll under the blade into the area
between the bottom of the blade and the ground level. A
rear gate, forming the back of the car ying bowl, is then
pulled forward to push out all the remaining dirt and allow
its Spread under the blade.

For jobs requiring a smaller scraper there are several
kinds of two wheel scrapers made. Host of the two wheeled
scrapers are similar in operation to the already described
four wheeled models. The Heil Company manufactures a two
wheeled scraper that dumps its load from the rear of the
bowl. In all models of two wheeled scrapers the load is
more or less balanced over the wheels when it is in the
carrying position. The capacity range of these scrapers is
from two to four cubic yards.

The tractor drawn dump wagon is similar in many respects
to the tractor drawn scraper except that it can merely haul

and dump its load. The most widely used type of dump wagons

32

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33

is the bottom dump type. The construction of these wagons

is such that the bottom of the carrying bowl consists of

two doors which open from the center outward. These doors
are operated by a single cable from the cable power control
on the tractor. Since these wagons do not have to load
themselves, it is possible for them to have enough clearance
so that the bottom doors may be dropped completely open and
still not interfer with the operation of the unit by dragging
in the dirt.

Another type of dump wagon is the side dump. Dumping
to the side is accomplished by tilting the whole carrying
box. The capacities of these dump wagons range from six

ubic yards to the huge coal haulers of he ton capacities.

With the advent of high speed rubber tired hauling
equipment, it became apparent that the conventional methods
of loading sometimes impaired the efficiency of the hauling
unit. Large capacity and speed on the haul road were in
many cases offset by limitations of loading equipment. In
order to reduce hauling costs to the lowest possible figure,
the Euclid Road Machinery Company has designed a loading
machine that has proved to be one of the most important de-
velopments for the earth moving industry in recent years.
Built to match the efficiency of other large earth.moving
eouipment, the largest unit made weighs approximately 50,000
pounds. It has its own 150 horsepower engine to operate an

endless belt. The belt is angled up and out so as to dump

the dirt into a truck underneath.

For efficient use the quantities of dirt to be moved
should be large, the ground fairly level, and the distance
of travel area sufficiently great so that not much time is
lost in turning the unit around and maneuvering the trucks
or wagons under the belt.

The soil must be of a type that the cutting edge and
belt can handle. Scarifying or breaking up the soil may
ease the load on the cutting edge and help give an even
flow of dirt on the belt. Ground conditions should be such

hat the trucks or wagons being loaded have good traction
and do not get stuck easily.

It is extremely important for maximum production that
the output of the belt be balanced with the number of trucks
or wagons so that the trucks will not "bunch up" while wait-
ing to get a load or time be lost because a truck is not
available.

Because of the great weight of this unit and the power
required to take an even, deep cut, only the largest size
tractors made are suitable for pulling the unit. In this
work the torque converter tractor is valuable not only be-
cause of its size, but because it is the only tractor that
uses a hydraulic torque converter. The use of this converter
eliminates tae necessity of hundreds of disengagements of the
tractor master clutch as one truck pulls away and another

moves up.

355

Positive controls permit instant adjustment of width,
depth and angle of cut and make it possible to grade slopes
and ditches. All loader operations are controlled by the
tractor operator. The control lever assembly, consisting of
three levers mounted on the rear of the tractor are within
easy reach of the Operator. The speed of the engine is
controlled by a clutch to reduce the engine speed when the
belt is stopped and to open the throttle when the belt is
started.

A rooter is in reality an extra heavy duty plow. Since
it is used to break up around that is too heavy or hard for
other types of eauipment, it must be able to withstand the
roughest kind of treatment. Most rooters are made of heavy
steel plate welded into a box type frame. The wheels are
of the nonclogging, steel tread type to take the severe
shocks subjected to them and still give good flotation.

The number of teeth varies from one to three, and the max-
imum depth is about 30". The frame may be filled with water
or sand to give extra weight._ The depth of the furrow is
controlled by the tractor operator by either a hydraulic

or cable dantrol ystem.

housed each mmoHecO vwaosm w wcaadaa AOpOapp poakwho

 

37

MOTOR GRADERS AND EATRCL GRADEHS

The motor grader was originally developed for grading
and maintenance of gravel or rock surfaced roads. Modern
improvements, however, have given this machine a wide di-
versification of uses and made it a year-round machine.

Tandem rear wheels and leaning front wheels have im-
proved traction and steering. Equipped with a V type snow
plow, together with its standard blade, it is an excellent
machine for snow removal. It is used for terracing, bank
sloping, grading, leveling and shaping roads, shoulders and
ditches.

The rolling action of the well designed blades make it
an effective machine for mixing and spreading bituminous
materials. A scarifer attachment on the fron enables it to
break and loosen soil.

The blades can be turned through 360° so that the
machine can be used in either direction. The blade can be
moved to the side so that grading can be done on sloping
or vertical banks. Speeds up to 17 miles per hour enable
this machine to move rapidly from one job to another.

The patrol grader is primarily used for maintenance of
gravel or rock surfaced roads. It is smaller than the motor-

grader and costs less. Although it cannot perform as wide a

38

variety of jobs as the motor grader, it fills a need for a

lower cost unit wnere only limited work is reouired.

 

 

 

bladei

 

Heavy duty motor grader

40

BUCKET LOADERS

The bucket loader is a highly specialized machine
that has been develOped to load trucks and wagons. These
machines can be mounted on either rubber tires or crawler
tracks. The machine itself consists of a spiral digger
which digs the dirt and forces it toward the bottom of the
conveyor belt. On the conveyor belt is mounted a number of
steel buckets. These buckets have toothed cutting blades

as do the digg n, Spirals. The dug material is carried in

3
the buckets up to the top of the conveyor where it is dump-
ed into the waiting trucks or wagons.

The digging speed of the machine is about 27 feet per
minute and the traveling speed is about three and one half
miles per hour.

The conveyor boom can be lowered when the machine is
going from one job to another so that the necessary head-
room clearance is about ten feet. These loaders are

completely self-powered for both loading operations and

traveling.

hl

LONG RANGS EARTH MOVING EQUIPMEKT

The slackline cableway excavator is a machine that
digs its load, lifts it free of the excavation, conveys,
and dumps it at any pre-determined point along the Span.
The combining of digging, conveyini, elevating, and dumping
in one continuous rapid cycle of operation, makes it pos-
sible with this machine to move material from a deep ex-
cavation directly to an elevated dumping point at a minimum
cost per yard.

The Operating principle of these machines is very
simple. The digging bucket is suspended from a trolley
carrier which travels on an inclined track cable. This
track cable is slackened off to lower the bucket into the
excavation, and tightened to lift the bucket into the air
for hauling up to the dumping point.

The power unit is a two drum hoist. A load cable,
attached to the front of the bucket, leads over a guide
block at the top of the mast or tower down to the front
drum of the hoist. With the bucket resting on the ground,
a short forward pull on the load cable causes the bucket
to dig in anifill to capacity. After the bucket is loaded,

the track cable is raised by winding up the tension cable

'42

on the rear drum of the hoist, thus causing the bucket to
clear the unexcavated material. The load is then conveyed
along the track cable to the dumping point by winding up the
load cable.

The chain mountings by which the bucket is suspended
from the carrier are so arranged that the bucket automati-
cally tips forward and downward when the load cable has
pulled it to a point where a dump block, which is attached
to the mountings comes in contact with a stop button on the
track cable. This stop button of course is so located that
the material is dumped at the appointed place. After dump-
ing, the empty bucket returns by gravity down the track
cable to the desired digging point.

Most generally this type of machine is used where the
material to be excavated has a good depth, and also where
the material is of a nature that will cause it to cave or
flow to the bottom of the out. Operating under these condi-
tions the line of operation does not have to be changed very
often. To take care of such shifting as is necessary, the
machines are equipped with a simple shifting device. In
principle this consists of a bridle cable running at right
angles to the track cable. The ends of this cable are an-
chored by means of deadmen anchors. A movable frame on
the bridle cable provides a means of attaching the outer
end of the track cable. This frame is held in place on.the
bridle by means of large clamps. When it is necessary to

change the line of Operation the bolts of these clamps are

A3

loosened and they, together with the bridle frwne, are
moved along the bridle cable to the desired location. The
clamps are then tightened and the operation proceeds.

Where machines are to be Operated in non-caving mater-
ial, or where the material to be excavated is shallow as to
require frequent shifting the, to bring out the greatest
efficiency of the machines, some method of rapid shifting
devices take different forms, depending upon the require-
ments of each individual job. At times they may be in
principle to the ordinary bridle anchor, but with power pro-
vision for moving the bridle frame. Then again it may be
preferable that a moving tail tower be provided for the
outer end of the machine.

Each size of machine is provided with a cableway hoist
of the proper size and power. The front drum of the hoist,
which handles the load line, is equipped with two speeds of
Operation. In digging, when a slow powerful line pull is
necessary, the low speed of this drum is used. Then when
the bucket is conveyed to the dumping point, and a high
line speed and a comparatively low power is required,t;he
high speed gearing of the front drum is put into operation.
This allows the greatest degree of efficiency in the oper-
ation of these machines. These hoists are powered with
electric motors, or gasoline or Diesel engines, or can be
operated by belt drive. Steam Operated hoists can be fur-

nished when necessary.

The labor requirement for operating these machines is
ve y small. Most installations require the full time of
only one man, and that is the operator of the hoist unit.
Occasionally for oiling, changing of the line operation,
etc., he part time services of another man will be required.

The machines are economical in their consumption of
fuel and power. As it will be noted that for a considerable
portion of the cycle of Operation, when the empty bucket is
returning to the digging point, no pover is required.

There is a minimum number of wearing parts and conse-
quently the maintenance expense is very low.

Slackline cableways are divided into three distinct
classifications according to size. These are:

(1) Small slackline cableway excavators with

bucket capacities of 1/3 to 3/h cubic yards.

(2) Medium slackline cableway excavators with

bucket capacities of l to 2 cubic yards.

(3) Large slackline cableway excavators with

bucket capacities of 2 cubic yards and over.

The power drag scraper is a powerful excavator and a
rapid conveyor. It reduces to simplest terms the long
range handling of materials; earth, clay, broken rock, coal,
and bulk materials.

The equipment consists mainly of a bottomless scraper
bucket attached by front and rear bridle chains to two long

wire cables, one known as the load cable and the other the

1L5

backhaul cable, which winds and unwinds on two-drum hoists.
At the head end of the installation, both operating cables
pass through guide blocks attached to a head frame or mast.
At the rear end of the installation, the backhaul cable
passes around a movable tail block.

The power drag scraper is very easy to operate. Mater-
ial can be dug, conveyed considerable distances, and auto-
matically dumped without introducing any other labor or any
intermediate handling equipment. More important still, this
long line of operation can be shifted over a large area with-
out delay or difficulty, simply by changing the location of
the guide blocks. The delivery point may be a hopper, crusher,

car, truck, or storage place. Dir ing and dumping points can

\DL.)

J..1

both be controlled wit the required accuracy. A power drag
scraper will dig any material that a plow can penetrate.
It will operate on a hillside or on mushy ground as well as
on dry level ground.

Drag scraper machines are built in numerous sizes and
variations. The capacities of the buckets vary from 1/3 to
5 cubic yards.

The main items that make up a complete drag scraper are:

(l) A scraper bucket; (2) A set of guide blocks; (3) A set
of operating cables; (h) A complete bridle anchor; (5) A
gasoline, Deisel, electric, or belt drive hoist.

The following items may be required: (6) Guy cables;

(7) A hand operated rapid shifting device (8) A power-oper-

ated rapid shifting device.

as

The tautline cableway is a very specialized type of
long range excavator. It is used for various material
handling problems where the material has to be picked up,
conveyed, and lowered. They are equipped with either skips
or with orange peel buckets. These machines are designed
in three types: (1) Both towers stationary; (2) One tower
stationary and the other traveling radially; (3) Both
towers traveling on parallel tracks. Load capacities range
from one ton to twenty tons; Spans range up to 500 feet,
for the one ton to five ton cableways, and up to 2000 feet

or more for the larger cableways.

TRENCHSRS

Almost all large scale trenching that is done today is
done by mechanical trenchers or ditchers. These machines
are of two main types. The first type, used mostly for the
smaller trenching jobs, is the wheel trencher. The prin-
ciple of operation is a wheel on which is mounted a number
of digging buckets. These buckets are lowered to the desired
depth with the wheel turning. The buckets dig into the earth
and throw the dirt up onto a short conveyor which dumps the
dirt to the side. These machines are the most rigid type
of trencher made.

The larger machines are usually of the endless belt or
conveyor type. In these machines the dirt is dug by a num-
ber of buckets which travel on a chain belt about an adjust-
able boom. This boom may be set at the desired depth. The
buckets empty into a conveyor which empties to the side.
Some of the largest machines have two booms that work side
by side. The larger machines are used where a deeper trench
is needed.

The dieging speeds of both types are from 2.5” to 118”
per minute. The maximum digging depth of the wheel type is
about 5'6". The maximum depth of the ladder type is about

20'. The maximum width of trench dug by the wheel type

i?
L‘

using sidecutters is 36". The maximum width of trench dug
by the ladder type with sidecutters is 72".

The wheel types usually have about twenty-five digging
speeds while the average number of digging speeds for the

ladder type is about forty-five.

1+9

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TRUCKS

Almost eVery manufacturer of motor trucks makes at
least one model that can be used as a dump truck. These
trucks range from the lirht weight Ford and Chevorlet
trucks to the special built Mack and Euclid models.

The smallesttruck made that is suitable for a dump box
is a two ton size, while the largest dump truck made today
is a 32 ton size. All of the recently manufactured trucks
have hydraulically raised dump boxes.

The engines that power these trucks range in power
from 9h horsepower to 275 horsepower. The smaller of these
engines are gasoline while the medium size are either gas-
oline or Diesel, and the largest are all Diesel.

The lifht-weight models usually have four forward
speeds and a two speed axle. The heaviest trucks have six
or eight forward speeds and a two speed axle.

A typical small dump truck will have a gross vehical
weight of approximately 12,000 pounds. The minimum turning
radius is about 35 feet. The maximum empty speed is about
60 miles per hour51nd the loaded speed about 35 miles per
hour.

Two manufacturers of trucks, Mack and Euclid, make extra

large heavy-duty trucks. The Euclid 22 ton rear dump model

 

‘ Heavy duty Euclid truck

§pecifications
1h.8 cu.yds. struck measure.

hh,OOO lb. payload capacity.
225 to 275 h.p. Diesel engine.

Top loaded speed 31.2 m.p.h.

51

52

has a gross vehical weight of 8h,000 pounds. The maximum
loaded speed is about 28 miles per hour, and the maximum
empty speed is 31 miles per hour. The minimum turning
radius is 63% feet.

There are a number of specially designed dump trucks
in use at the present time. A typical one, the Koehring
Dumptor, has its dump box in front of the driver. The box
is dumped by gravity, and the capacity of the box is six

yards.

53

EQUIPMENT TRANSPORTATION

One of the major problems of excavating engineers is
the transportation of heavy equipment.

For long hauls the equipment that cannot travel under
its own power is shipped by railway. Often such equipment
as heavy trucks travel under their own power, at the same
time transporting other equipment.

Highway transportation of heavy equipment requires a
large pulling truck anl a large flat-bed trailer. These
trailers are capable of carrying very heavy loads and still
keep within the highway load limits. This is done by in-
creasing the number of wheels, thereby decreasing the bearing
pressure. These trailers are of the low-bed type so that
the equipment they are carrying will require as little head
clearance as possible.

The capacities of these trailers range from eight tons

up to 67 tons. The maximum haulini speed of these trailers

a
is seldom over 20 miles per hour. Flat-bed trailers are all
purpose trailers and may carry almost any kind of heavy load.
Some trailers are made to carry only one piece of equip-
ment. They are called single purpose skeleton trailers be-

cause they consist of a frame mounted on mzeels. Such

trailers are usually made for small or medium size shovels.

The trailer is loaded by running the shovel up on blocks
and then running the trailer with the front wheels removed
in under the shovel. The front wheels are then attached to
the frame and the blocks removed. This type of trailer is
not suitable for the larger type of shovels.

For small earthmoving equipment light weight two-wheel
trailers are often used. These can be pulled by smaller
trucks and cost considerably less than the large multi-

wheeled trailers.

55

BLASTING AQJIPQJNT

Blasting is a means of aiding excavation that is
efficient and relatively inexpensive, but often overlooked.
Many engineers do not realize how much blasting can speed
up excavation Operations.

For blasting rock the equipment necessary consists of
drills that are capable of sinking holes for the charges,
the blasting machine, caps and wires, and the explosives
themselves.

The types of drills that are available for rock drill-
ing are varied and numerous. They range is size from small
hand operated "jackhammers", to large quarry type drills
that are mounted on crawlers.

For small jobs the blasting holes may be sunk with
hand operated drills. These drills are easily moved, easily
operated, have small initial cost, and require little upkeep.
The main disadvantage of these drills is that they are limit-
in the size and depth of hole they are capable of drilling.

The next larger type of drill is the wagon drill. This
drilling outfit consists of an air drill mounted on a three

wheeled wagon. These drills are capable of sinking holes

up to twelve feet deep. They are reported to drill more

I

50
than twice as fast as a hand held drill because of the more
even pressure on the bit. A wagon drill is generally oper-
ated by one man.

When sinking holes in tunnels or in mines drills called
drifters are often used. These drills are mounted on a
mounting which consists of a vertical post to which the drill
is clamped so as to allow drilling in any direction. The
forward motion of the drill is actuated either by hand or
by an air powered motor.

In quarries and on very large construction jobs such
as dam construction, a type of drill that is becoming in-
creasingly popular is the large rig type drill that is mount-
ed on crawlers. These drills have made amazing reductions
in rock drilling by combining mobility, speed in drilling
deep holes, and low up-keep. The newer models are equipped
to rotate the drill point in addition to the vertical blows
which occur over 200 times per minute. The latest models
also have a method of cleaning the cuttings out of the hole
which increases the drilling speed and can be Operated in
any weather. This method is to force air into the hole
through the center of the drill shaft. A suction hose covers
the top of the hole. The cuttings are thereby forced out of
the hole without the use of water. This method is not hamp-
ered by cold weather which would freeze water if it had
been used.

The drills discussed above have been described in re-

lation to blasting. Many of them are equally well adapted

57

to rock drilling operations other than those connected with
blasting.

The actual blastin: equipment consists of blasting
machines and their allied equipment. Blastinfi machines are
usually made in three sizes. On large jobs a 50 cap or a
30 cap machine is used. For small jobs blasting men usually
prefer a twist type 10 cap machine. The size of machine is
designated by the number of electric blasting caps for which
it can supply sufficient current for detonation.

The large machines are preferable where there is a
large amount of blasting to be done because it provides a
means of detonating the charges simultaneously. S'multaneous
detonation of a number of charges increases the efficiency
of the explosive considerably. These machines are actually
a generator which is operated by forcing a plunger down.

The handle of the plunger protrudes above the top of the
case while on the bottom of the plunger is a gear rack which
meshes with a gear on the Shaft of the generator.

The 10 cap machine is much lighter than the larger
machines, weighing only 5 pounds. It is operated on the
same principle except that the generator shaft is turned by
twisting a handle instead of a plunger. Though these mach-
ines have a 10 cap capacity they are often used in preference
to fuse caps on single charges because of the increased safety.

Any electrical circuit used in blasting should be check-
ed before use with a galvonometer. This insures a good cir-

cuit without the danger of any charges being set off.

I’}

So

The eXplosives themselves vary greatly in their char-

acteristics with each different type going under a manufact

urer's tradename. The power of various eXplosives is

gener-

ally classified usinz the power of straight nitromylcerin

dynamite as a standard.

In recent years the trend has been towards safer
plosives, that is, explosives that are more difficult
detonate. Many of these new types of explosives have
ammonium nitrate for a base instead of nitroglycerin.
have almost as much power as the nitro-dynamites and,

for grade, cost less.

8X-

to

They

grade

59

The various types of equipment that have been describ-
ed in part one have been developed because of the inadequacy
of former equipment to do a job efficiently.

With the many types of equipment that are in use today

t is obvious that the work zones of one piece of equipment

P-

will overlap the work zones of other ecuipment. This con-
dition requires that each job be analyzed to determine what
equipment will do the work most efficiently.

To facilitate the discussion of job analysis it can be

roken down into two component parts as follows: (1) the
selection of the right type of eouipment; (2) the selection
of the right size of eouipment.

A discussion of the first part, the selection of the
right type of equipment, brings up the reasons for building
the five types of front end operatine eauipment used on power
shovels and cranes. To understand the applications of the
various types of front end eouipment it is necessary to know
the advanta es and limitations of each.

In starting with the shovel it will be noticed that its
design permits power to be applied so as to force the dipper
into the material being dug. It is because of this charac-

teristic that the shovel is a postive digging tool that is

63

capable of digging the hardest materials. The shovel will
dig anythinr from sand to rock. The following paragraphs
tell how a shovel can be used.

A shovel will dig a bank of rock or dirt. Practical
applications of this would be digging in a gravel bank or a
clay pit, strippi g overburden, making cuts in highway con-
struction, or any job where there is a good bank to work
against.

The shovel will also work below grade or ground level
for construction of shallow ditches or roadside berms. It
will dig a trench, the depth of which is limited by the
length or reach of the dipper stick. Although this is not
a typical or usual application of a shovel, it does indicate
a possible use of this type of unit for short or emergency
jobs such as road culverts or cross drains.

Another possible use of a shovel is to control the
dipper so that it makes a horizontal cutting stroke. This
is useful in finish grading. This type of operation is also
used in stripping topsoil. A slight variation of this type
of control is to have the dipper cut on an angle so that it
may be used to slope, dress or trim slopes or banks.

After the dipper has been filled it must be dumped. One
method of doing this is to load into hauling units at the
same level as the shovel. Another method of dumping materials
is to load into hauling units which are above the ground or
digging level. This is often necessary because of space

limitations, poor drainage, and other conditions. In this

Stripping coal with a 35 cubic
yard shovel

61

 

case the height of the bank on which units may be loaded
is controlled by the ranges of the shovel boom and stick.

Often when stripping overburden the shovel will dump
its load into spoil banks. When working on hillside or
mountain highway construction a shovel may dispose of its
lead by casting it over the lower bank. When shovels are
used in gravel pits or other pits the load is often dumped
into a belt conveyor or a grizzly.

To summarize, a shovel should be used under the follow-
ing conditions:

(1) Where the material to be dug is firm or hard.

(2) Where the excavation is large enough, or covers

enough space to provide sufficient working area

for the shovel to work and for hauling Quip-
ment to have access to the shovel.

(3) Where the disposal of materials reouires dump-

in; above or at ground level.

(h) Where the nature of the excavation provides a

sufficient depth to utilize the full produc-
tive ability of the shovel.

In the followinf discussion, the working applications
of the common crane boom will be confinaito clanshell 31d
dragline work.

A clamshell can dig or spot dump below or at, or above
the level of the machine. Because of this it is an ideal
machine for handling or placing material at a higher or
lower level the would be possible with the shovel or drag-

line.

fottings, pier holes, trenches, or cellars. This digging
application indicates how the clamshell may be used to dig
'downwardly in a vertical direction for digging pier holes,
footings, etc. Another ditging application of the clamshell
is to dig trenches or work in trenches which are sheathed
and have criss-cross bracing. In the latter case the clam-
shell bucket, operating in a vertical direction, can be
easily dropped and worked throught3he bracing of the sheath-
ing. Another useful adplication of the clamshell is to trim
banks. This is done by resting the bucket on the top of the
bank and letting the weight of the bucket cause it to slide
down the bank, trimming the surface as it descends.

Clamshells are also used on many material handling
jobs, on construction jobs and around industrial plants.
Typical uses for these jobs would be loading or unloading
railroad cars where accurate digging and dumping are needed.
The height of the boom is put to good advantage when build-
ing stockpiles. The height of the clamshell is also util-
ized when charging high bins.

To summarize, the broad general conditions Whidl control
the use of Clamshells are as follows:

(1) Where the materials to be dug are relatively

soft or loose up to medium hard.
(2) Where the di

gin and material handling is in

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a vertical plane and below, at, or above the

ground level.

(3) Where the digging is practically straight

down, as in digring shafts.

(h) Where accurate dumping or disposal is

required.

(5) Where high dumping is required such as

building a stockpile or charging bins.

(6) Digging sheathed trenches.

A dragline is used to dig dirt, shale and well shot
rock, to strip overburden, dig basements and borrow pits.

When using the dragline to dig trenches the trenches
may be of three types: (1) with straight vertical side walls
where the material will stand, or (2) with V-sloping side
walls. The depth of the trench is limited only by the
length of the cable. Like the clamshell, the dragline can
load into hauling units or onto spoil piles.

As already stated, the dragline can dig well below the
ground level. It is best adapted to jobs where the mater-
ials are soft to medium hard. The dragline is ideal on jobs
where wet bottom conditions exist. In this case the unit
may remain on the top on cry, firm footing. Cleaning ditches
and dredging river sand and gravel are typical conditions.

Where it is desired to cast or dump the material as far
from the unit as possible, the dragline is the ideal unit.
The long, low booms used on draglines usually permit dumping
material farther away from the unit than vith any other
method. However, hauling units may be loaded with the drag-

line where materials must be removed to a greater distance,

on
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or materials may be re-cast by the dragline.

The hoe may be said to be a cross between a dragline
and a shovel as it incorporates some of the characteristics
of each and overcomes some of the limitations of each. The

hoe, of course, is orimarilr a unit to dig below ground

A O

J-

level. It will, however, dig harder materials than the clam-
shell or the dragline because the weight of the boom itself

1
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may be used to force or crowd t.

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nto the material.

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It is limited in digging depth by he length of the boom
and dipper stick. The hoe dipper may be more accurately
controlled than the dragline bucket and is therefore better
suited for close limit work.

The hoe is used to dig trenches, footings, and base-
ments. On small residence basements the hoe offers many
advantages. It digs straight, vertical walls, it cuts a
level floor, it trims corners neatly and squarely, it can
dig sewer and water connections, it always works from the
top on dry safe ground, and it reduces hand trim to a
minimmn.

Digging trenches is naturally one of the primary and
universal uses of the hoe. Its ability to dig hard materials,
to be controlled precisely, to cut straight walls and to
grade the bottom of the trench, are all advantages of the
hoe on this class of work.

The hoe may dispose of materials in two ways, either
load into hauling units or dump onto spoil banks.

In general, a hoe should be used under the following

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Rock excavation with a 1/2 cubic yard shovel

conditions:

(1) When the excavation is below ground level.

(2) When the material to be dug is firm to hard.

(3) When the ekcavation must be trimmed closely.

(h) When the disposal or dumping of the materials

is at rather short range.

After the determination is made of the proper type of
boom to handle the job or material, the question of the pro-
per mounting should be considered. Here again the discussion
must be very general as the correct solution can only be made
when the actual job conditions and requirements are known.
Generally it will be necessary to consider the ground or sur-
face conditions of the job and the recuired mobility on the
job to determine the proper mounting.

Generally the crawler is a universal type of mounting
that can be used under almost any and every job condition.
The crawler, of course, is the best mounting for soft ground
or wet bottom conditions.

The crawler, however, has a top speed of only approxi-
mately 1% to 2 miles per hour. It therefore should not be
moved long distances under its own power. This would be very
severe on the crawler mechanism, and incidentally, long ‘is-
tance crawler travel is restricted in some sections of the
country. The alternative is to use a trailer and a towing
unit.

On the other hand, there are many operations that call

for constant and relatively rapid movement of the machine

68

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09

around the job. Further, there are many smaller jobs that
require shovel or crane efficiency but will not stand the
expense and time of moving equipment that lacks rapid mobil-
ity. Rubber tired mountings best meet these requirements.
The single engine or wheel mounting usually provides one to
four speeds ranging from one half to ten or twenty miles
per hour.

All controls for such units are located in the Opera-
tor's cab and steering, backing, and gear shifting are ef-
fected from this position.

The truck type mounting is automotive in character.

It provides the maximum in mobility both as to speed and
distance. Usually the units provide four to ten speeds with
a range of one to thirty miles per hour.

Further such vehicles are generally uilt with multiple
axles and with dual tires to provide tire capacity for soft
ground flotation which enables the unit to operate as an off
the highway vehicle. As such it is not limited to hard sur-
face roads but can be used, within reasonable limits, for
cross country, off the road travel, at lower speeds.

The next consideration is the determination of the size
of machine for the job based on the output of the machine or
the output required by the job.

To estimate the yardage production on a job is a real
problem. If all conditions were tne same on all jobs, it
would not be difficult, but jobs are as different as night

and day. There are many factors which must be considered,

70
some of can be learned through eXperience only.

For instance, the chart titled "Power Shovel Yardages”
has been developed to indicate how the type of material dug
affects the hourly yardage output. The top line covers ”hoist
Loam or Sandy Clay”, the middle line covers ”Clay, Hard,
Tough", the lower line covers "Rock, Poorly Blasted." Hourly
yardages for these materials are given for machines of 3/8
to 2% yard capacity as listed across the bottom of the chart.

If a 1% yard shovel is taken for example, note that the
output may vary from 115 yards per hour for poorly blasted
rock to 265 yards per hour for moist loam. Similar varia-
tions in yardages exist for machines of all other capacities.

It should be kept in mind that the figures in the yard-
age chart are based on the following conditions.

The first is that tie cubic yards per hour are bank
measure which means that they are cubic yards in the ground
rather than cubic yards in the hauling unit. There is a
big difference between a cubic yard in the bank and a cubic
yard in a truck. This is because of the swell of the earth
or its increase in volume due to voids when it is dug and
loosened.

The second condition is that the machine is working at
a cut of a depth that is suitable for maximum digging effic-
iency. This depth may be called the optimum depth, and may
be defined as follows: the optimum depth of cut for various
sizes of shovels may be defined as "that depth of out which

produces the greatest output and at which the dipper comes

71
up with a full load without undue crowding." The optimum
depth does not represent and has nothing to do with the
maximum digging range.

Thirdly, the output figures are based on continuous
operation, 60 minutes per working hour, without any delays.

Fourth, these figures are based on each dipper full
being swung through 90° of are before dumping. This is im-
portant since a larger swing or a smaller swing will either
consume more time or save time.

Fifth, these tables are based on all materials being
loaded into hauling units. With the further understanding
that the hauling units are properly "sized" to shovel capac-
ity and that there are enough of them to take away all of

the material which the shovel can dig.

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72

It is important to note how the degrees of swing and .
the optimum depth of cut affect shovel yardage output. Since
variations in either of these conditions will have a consid-
erable effect on the yardage output, a chart has been pre-
pared to show what happens when swing and depth of cut vary
from the conditions on which the previous basic hourly yard-
ages are established.

At the top of this chart is shown a line covering the
reduction in swing from 900 to hSO, the middle line shows
the 90° used in the previous chart, the bottom line shows
the variations when the swing is increased from 900 to 180°.

Across the bottom are plotted percentages covering

variations in the depth of optimum cut.

 

There are two sets of factors on every job which have
a great deal to do with the output of the equipment on the

job. They are the Job Factor and the Management Factor.

73

Job factors are the physical conditions which pertain
to a specific job. They affect the production rate but do
not include the class of material to be handled. Job
factors may be divided into three main headings:

(l) Topography and the dimensions of the work.

(2) The surface and weather conditions.

(3) The specification requirements.

The management factors are the factors which affect the
output through the efficiency of the operation. These
factors include the following:

(1) The selection, training, and direction of men.

(2) The selection, care, and handling of equipment.

(3) The planning and laying out of the job, and the

coordination of the operations.

To further emphasize the importance of selecting the
right tYpe of machine for a job the following two tables
have been inserted to give an accurate comparison of the
yardage outputs of two machines that are often regarded as
interchangeable in their applications. These tables are the
sane in every way as the tables on shovels with the excep-
tion that these tables pertain to draqlines.

It might be added that in using these tables the
conditions under which they apply are just as important as
the figures on the yardage output and they should be
thoroughly studied to ascertain the results that any change

might cause.

7L!-

 

TRACTORS

A tractor without any mounted equipment is primarly a
piece of equipment for pulling other units. This is true
of both crawler and wheel tractors. Because of the great
number of differences in the design of tractors they are
used for pulling everything from small wagons to 25 ton
loaders and 30 yard scrapers.

In the design of the crawler tractor speed has been
sacrificed in order to increase traction, flotation, and
ability to withstand rough use. This type of design makes

he crawler tractor suitable for pioneer work, that is, work
where there are no roads.

The three most important "pulling" jobs of a crawler
are pulling scrapers, rooters, and leaders. The crawler is
well suited to pull these units because it is capable of
exerting an extremely large, slow pull.- The pulling of dump
wagons is usually done by large wheel tractors since wagons
are generally used where the ground conditions are fair to
good.

The duties of the two wheeled rubber tired tractor need
little explanation since these units are usually designed
for one purpose and are not suitable for other uses. They

will be covered later in the section on scrapers.

f

70

One additional advantage of the crawler tractor is that
the vibration of the running tractor along with the great
weight of the tractor produces an excellent combination for
compacting earth. Crawler tractors are seldom used solely
for compacting earth, but it is a useful feature when bull-
dozing and spreading with scrapers.

Both crawler type and wheel type tractors are used to
mount various equipment such as winches, small bucket loaders,
bullclams, and skid loaders.

Crawler type tractors and the new Le Tourneau four wheel-
ed tractors are widely used as pusher units fq~ tractor-

scraper units.

77

TRACTOR MOUNTED EQUIPhEKT

The list of tractor mounted ecuipment is generally
started with the bulldozer. The ”dozer” family includes a
number of variations of the basic bulldozer. These differ-
ent types were listed and described in Part I.

The function for which the bulldozer was originally
designed is the clearing of land. There is no other piece
of equipment that is able to clear land so easily and effic-
iently. For this job of clearing land a straight bulldozer
blade may be used, or a specially designed blade such as an
angle dozer, a blade with an extension for giving more lever-
age when felling trees, or a blade fitted with a number of

teeth to give added digging

J

ability. The latter type of
blade not only clears the trees and brush on the surface,
but it also rakes out all underground root structure and
large rocks. This is an advantage since it leaves the land
ready to plow.

The most common use of bulldozers other than clearing
is in short haul excavation. This might be said to cover
all excavation up to 300 feet. Many contractors use dozers
over longer distances. For ordinary digging there is little
choice between the straight blade and the angled blade. In

light material the angledozer with the straifiht blade setting

(K

70

carries slightly greater loads because of the wider blade.
The digging pass is generally made in low gear and some
times in second gear. The return is made in high gear. In
some modern tractors it is not necessary to turn around even
to return on long hauls, as the tractor can be backed at
high speed simply by shifting the reverse lever. Reverse
speeds in these models are as fast as the forward speeds.
This has materially increased bulldozer production and in-
creased the length of profitable haul. Forward Speedvvith
a load averages about 132 feet per minute, and return speeds
are now available in a range up to h75 feet per minute.
Bulldozer dirt production is greatly increased by push-

ng down hill or cutting in a slot. The curvature and tilt

i—Vo

of the blade should be such as to cause the dirt to be rolled
away rather than to be just pushed along. The consistency
of the dirt will have a direct bearing on this.

Besides short haul excavation, in which the bulldozer
cuts longitudinally down a hump and places material in a low
spot, side borrow is often resorted to, working at right
angles to the location line, pushing materials toward the
center from both sides. Typical of this work is ditch ex-
cavation to crown up old roadways, or nearby excavation to
throw up a small levee or embankment. These last are obvious-
ly only feasible on flat alignment.

Bulldozers may also be used for charging traps and
grizzlies by using a ramp.

Bulldozers are not generally considered as finishing

79
equipment. They may however be used to do rough finishing
such as Spreading piles of dirt left by dump trucks. The
main reason that the bulldozer is not suitable for close
finishing is that the wheel base of the tractor is so short
as to cause a bobbing of the blade on anything but the slow-
est of travel.

An increasing number of tractor shovels are being used
where the two operations of bulldozing and loading occur at
the same time. When the bucket is in the down position it
is essentially the same as a straight bulldozer, in fact
there are many more times when such units are used in the
down position than as a loader.

Loading trucks is an operation for which the tractor
shovel is ideally suited. For efficient operation, the
tractor, after it is loaded should not have to travel more
than l0 or 15 feet to get to the truck. Distances greater
than this result in too much lost time in traveling. If pos-
sible the tractor should dig in a ninety degree or less are
from the truck. Observance of these two principles will
enable the unit to service more trucks per hour.

There are a number of other units such as winches, hoists,

etc. that can be mounted on tractors. These are not used

for earthmoving and so will not be discussed here.

60

GRUBBEQ“

NVRC'L UNITS SCRAPER’EL’LlLTRA: ER D In L'NITS

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fixamples of tractor drawn and tractor

mounted equigment

TRACTOR DRAWN EQUIPmEh

The tractor drawn scraper should always be considered
where the three operations of loading, hauling, and spread-
ing occur together.

When working in borrow areas the power for the scraper
may be furnished by one pulliny tractor, or by an additional
tractor that helps by either pushing or pulling. In order
to be economical, a helper tractor should be able to service
several scrapers. Usually this is not possible if the
length of haul is very short since the scrapers would tend
to bunch up behind the helper. When using some of the small-
er models of scrapers one tractor may be used to pull two
scrapers. In this case it is necessary for the tractor to
have a dual set of controls to operate both scrapers. The
scope of the job will determine the most economical size of
machinery to be used.

A scraper is especially suited to working on fills. The
material is carried over the previously spread dirt so that
the weight of the unit helps in compacting the fill at the
same time it is spreading its load. When using scrapers on
fills, the fill should be maintained high against the out-
side slopes. This keeps the scraper from sliding down the

slope, and destroying it as it would if the outsides were left

low. Routing scrapers over different paths adds to the
compaction of the fill.

A scraper will spread its load in the sane time a truck
will dump its load, so the cost of the spreader accompanying
the truck is saved by using a scraper.

In many instances the tractor drawn scraper is used as
a finishing tool. The following features make them units
that are capable of precise finishing work:

(1) A long wheel base that stabilizes the action

of the blade

(”) The ability to skim very thin layers from

high spots and to carry them to low spots
for di3posal, alonq with several additional
yards for that purpose if desired.

(3) 7 to 10 ft. blade widths under precise,

rapid control

(4) Works on slopes up to 2 on 1 transversely,

to finish slopes.

The deciding factor on choosing between a crawler type
tractor and a two wheeled rubber tired type for pulling
scrapers is the length of haul. While the crawler has sreat-
er traction and therefore may get binder loads without a
helper, it is not generally efficient on lonh hauls. The two
wheeled type needs a helper tractor to get a full load, but
it hauls at truck speeds so that it is suitable for long
hauls.

The tractor drawn loader for use on large excavations

83
was described in Part I. The factors determining the app-

lication of the unit were included in the description of the

design, therefore it will not be necessaiy to repeat them

The tractor drawn ripper is used for breaking ground
surfaces that are too tough for other equipment. When a
contractor can avoid using a ripper he will do so since it
is always an extra operation. The surfaces that usually
require a ripper range from hardpan and shale to old pave-
ments. These tools are always pulled by a crawler because
of the great force necessary to force the teeth through the

hard surface.

MOTOR GRADERS AKD EATRUL GhADERS

The uses of the various types of graders were discuss-
ed in some detail in Part I. They are made in two general
sizes. The large size is called a motor grader, and the
smaller size is called a patrol grader.

The motor grader is used for finishing work, surface
material mixing, and snow removal where considerable power
is needed. For sloping ditches, shaping road shoulders, and
other deep cut precise grading jobs there is no other piece
of equipment as nearly suitable as the heavy duty motor
grader.

There are many grading jobs which do not require as
heavy and powerful a machine as the motor grader. On these
jobs it is often wise to use a patrol grader, thereby saving
on both the initial cost and the operating costs. The patrol
arader is well suited to most grading operations where a
deep cut in heavy material is not common. Maintenance of

gravel surfaced roads is a common job for the patrol grader.

«

BUCKET LOADERS

The jobs that require a bucket loader, other than snow

removal, are usually around material ts and stock piles.

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Since these machines will not dig into hard surfaces they
are not suited to most jobs that occur in the field. In use
with loose materials such as gravel and sand, these machines
will load small to medium sized trucks as fast as a shovel,
are more easily moved from one location to another, and are
more economical in both initial cost and operating costs.
Various models of these machines have specia attachments
which are designed for snow removal. This added feature makes
the bucket loader an excellent machine for municiple use,
since it can be used as an all season machine.
These machines are made even more versatile by the choice
of mountings available. For work on good ground surfaces
the machine may have a rubber tired mounting which allows
the machine to move from one job to another at truck speeds.

For use on wet bottom surfaces the machine is usually

mounted on crawlers.

o0

LOAG RAHGL EARTHMOVIHG EQUIPHEHT

Wherever it is necessary to dig materials from ponds,
rivers, deep pits, and move the materials to an elevated
delivery point such as a bin, hopper, or high pile, the
problem can often be solved by a slackline cableway exca-
vator. These machines, as can be seen from the description
in Part I, are suited to jobs that are more or less uncommon.

Both the slackline cableway and power dra~

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scraper types of
excavators are usually designed for Specific jobs. The man-
ufacturer usually makes a survey of the type and size of
machine needed for a certain job and then builds a machine
that meets those requirements. Because of this feature of
these machines, their application can best be illustrated

by the accompanying pictures.

 

 

Examples of slackline cableways as used

in open pit mining

88

 

gravel

Examples of slackline cableways excavating

under dry and wet bottom conditions

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90

TRENCHERS

A trencher is a very specialized type of excavator.

It was designed for one type of job, and while it does that
job well, it is not suitable for any other kind of work.

These machines are manufactured in a variety of sizes,
and are suitable for digging almost any type of trench.

They are best suited to large jobs such as pipe lines and
cable laying.

The size of machine required is governed by the size of
the trench to be dug and the kind of material encountered.
For cable laying projects where the trench has to be fairly
deep and not very wide, the trencher should be equipped with
as narrow buckets as possible. This reduces the amount of
dirt dug and it allows the machine to dig faster.

All standard models of trenchers are mounted on crawler
mountings. These mountings enable the machine to traverse
difficult terrain and still maintain a stable base which is
a necessary condition for digging a straight trench.

When digging large trenches the ladder type of trencher
is generally used. This type of machine will dig to a great-
er depth, and if an exceptionally wide trench is desired,
two side by side booms can be operated at the same time.

Although these large machines move many times the amount of

earth.moved bv the smaller models their air
a 2

are almost as great as the speeds of the smaller

91
speeds

machines.

 

Wheel type trencher cutting through

semi-solid rock

92

93

THUCKS

The design and size range of motor trucks is so wide
and varied that some model of dump truck can be found on
just about every construction project.

To start with the smaller sizes of trucks it may be
said that these trucks are the common means of hauling re-
latively small yardages of earth long distances. The three
main advantages of lightweight dump trucks are: (l) ease of
operation, (2) rapid traveling speed, (3) relatively low
cost.

The sizes of the trucks used on earthmoving projects
are determined by the yardages to be hauled and the con-
dition of the hauling road. The largest of trucks, such as
are built by Mack and Euclid, are capable of carrying huge
loads over the roughest of roads without any injury to the
truck.

The number of trucks that should be used on a job is
governed by the loading facilities. Generally speaking, if
a shovel with a large dipper is being used then trucks with
large carrying capacities should be used. This helps pre-
vent lost time caused by the trucks bunchilg up at either

end of the hauling cycle.

91L

BLASTING

Blasting is the mast efficient and the most inexpen-
sive method of dislodging solid and semi-solid rock so that
it can be handled by earthmoving equipment. Extensive re-
search has been carried on by the country's explosive manu-
facturers to improve agricultural and construction explosives.

In quarries and mines where rock is encountered in
large quantities the economical use of explosives requires
a considerable amount of rock drilling equipment. This
equipment may consist of anything from small hand drills to
large drilling machines which are mounted on crawler mount-
ings. Usually on large jobs it is more economical to use
large drilling equipment since more holes are needed and
faster drilling saves labor costs and increases production.
Past experiences have shown that it doesn't pay to go easy
on the number and sizes of charges used in heavy rock blast-
ing. Undersized charges often leave the rock in such large
clunks that secondary blasting is necessaryxwhich increases
the cost per yard and decreases production.

Pipeliners and dredge-boat operators often have the
occasion to use explosives. In trenching explosives are
especially useful in crossing rivers. In blasting trenches

for pipelines and cables across rivers where the water is

95
is comparatively shallow, it is common practice to tie
bundles of dynamite cartridges along a cable which is then
submerged and covered with sand bags. Since this is a rather
slow method, dynamite cartridges which can be fastened into
a single rigid charge are taped onto a cable and then drawn
across the river. When ditching with explosives in swamps
and other wet bottom land where it is impossible to use a
trencher there are two general methods which may be used.
The first method is the propagation method. The principle
of this method is the detonation of all of the charges by
one detonating cap. This can be done only in wet soils where
the concussion of the first charge to go off is transmitted
to the adjacent charge and so on down the line.

The second general method is the electric method. This
is done by priming each hole with an electric cap and then
setting off the caps with a blasting machine. This method
is the hardest of the two since each hole has to be primed,
but it is the only method that is satisfactory in dry soils
and rock.

Clearing land is often a job for blasting explosives.

9 land Of

k.)

It constitutes an inexpensive method of riddin
stumps and large boulders when heavy equipment is not avail-
able or is considered too costly to use.

In recent years it has become increasingly popular to
speed up the settling of fills by the use of dynamite.
Dynamite is also used to help the filling of "sink holes."

This is done by drilling holes through the topsoil where the

96
hole is to be filled and placing charges in these holes.
When the charges are set off they tend to force the unstable
soil to the side where it will not bother the fill.

When using explosives for almost any job it is possible
to obtain detailed instructions on their use from the manu-
facturer of the explosive. If the job is of considerable
size many of the explosive companies will send a technical

representative to aid in carrying out the Operation.

        
  

 

 

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MICHIGAN STATE UNIVERSITY LIBRARIES

II IIIIIII III

43219

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