heavy-duty vehicle

1. CHAPTER ONE
CLASSIFICATION OF CONSTRUCTION
EQUIPMENTS
1
Ambo University
Department of Mechanical engineering

2. Classification of construction equipments
• Heavy construction equipment are used for
various purposes in large construction projects.
• Selection of heavy equipment depends on the
size of the work and economy of the project.
• Proper use of the appropriate equipment
contributes to economy, quality, safety, speed
and timely completion of a project.
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3. Cont….
Depending on the application, construction equpments
are classified into various categories which are:
1. Earth-moving equipment
2. compacting equipment
3. Hauling equipment
4. Hoisting equipment
5. Equipments used in Concrete Construction.
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4. Cont….
Operations involved in construction of any project;
 Excavation
 Digging of large quantities of earth
 Moving them to distances which are sometimes fairly long
 Placement
 Compacting
 Leveling
 Dozing
 Grading
 Hauling
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5. 1. Earth moving equipment
The major excavating and earth moving equpments
are:
i. Excavators
ii. Bull dozers
iii. Motor graders
iv. Scrapers
v. Trenching machine
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6. i. Excavators
• The excavators are used for loading and digging of
earth that is below the machine.
• The upper swing unit can rotate 360°.
• Excavators are designed for multiple applications
including
 clearing,
 backfilling,
 excavating and
 loading
• They can be equipped with numerous styles of buckets
and accessories.
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7. i. Excavators
Excavators can be equipped with numerous styles of
buckets and accessories.
Types of excavators:
1. Power shovel
2. Back hoe
3. Drag line
4. Clam shell
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8. ii. Bull dozer
• It is a machine in which the heavy blade is attached
to the tractor which is used for pushing the material
from one place to another.
• The tractor can be of the crawler or the wheeled
type.
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9. iii. Motor Grader
 A grader is a construction machine with a long blade used to create a flat
surface.
 The grader's purpose is to "finish grade" (refine, set precisely) the "rough
grading" performed by heavy equipment or engineering vehicles such as
scrapers and bulldozers.
 Graders are commonly used in the construction and maintenance of dirt
roads and gravel roads.
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10. iii. Motor Grader
 In the construction of paved roads they are used to prepare the base
course to create a wide flat surface for the asphalt to be placed on.
 Graders are also used to set native soil foundation pads to finish
grade prior to the construction of large buildings.
 It is used for grading and finishing the upper surface of the earthen
formations and embankments. They usually operate in the forward
direction.
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11. iv. Scrapers
• Unique machine for digging and long-distance hauling of ploughable
materials.
• self-operating machine
• It is not dependent on other equipment.
• Wheels of machine cause some compaction.
• The basic parts of scrapers are the bowl, apron and tail gate or ejector.
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12. v. Trenching machine
 Trenchers, or ditchers as they are sometimes called, are similar to excavators
in the sense that they penetrate the earth, breaking soil and rock, and remove it
from the ground.
 Trenchers are specifically used for digging trenches for pipes, but other
machines have been improvised in the past to serve this purpose.
 Used for excavating trenches for laying pipelines, sewer, cables etc.
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13. 2.Earth compaction equipment
Rollers
• Rollers are machines used in the compaction of soils after grading.
Compaction reduces the volume of air space in the soil.
• This compaction increases the dry unit weight and strength of the
soil to better support structures.
• This is a very important step, and there are various tools to complete
this task.
• Rollers complete compaction using various methods: Pressure,
Impact, Vibration, and Manipulation.
There are three types of rolers;
a) Smooth-wheel rollers.
b) Sheep-foot rollers
c) Pneumatic tyred rollers
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14. Sheep foot roller Vibratory roller
• A sheep foot roller has almost hoof
like structures protruding from a
roller to offer pinpoint pressure as in
a herd of sheep was walking across
the field.
• A Vibratory roller is a heavy machine similar
to a sheep foot or tamping roller but adds
vibration.
• It utilizes eccentric(alternating) weights and
other methods to produce a vibration as it
drops them against the soil with a typical
frequency of 1000-3500 cycles, vibrating the
soil to compaction.
• Vibration is usually more effective in sandy
and gravelly soils. Can be effective up to 2m.
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15. Pneumatic tyre rollers
 Consists of a base plat form mounted betweentwo axles
 Tracks of the rear wheel lie in between the tracks Of the front wheel
 Compaction is by controlling the ground contact pressure
 Weight or width of the wheel can be suitably increased
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16. 3. Hauling equipment
• The equipment used for transportation of material are
known as hauling equipment or simply haulers.
• It involve
 transportation of building materials,
 carriage and disposal of excavated earth
 haulage of heavy construction equipment.
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17. 3. Hauling equipment
These are classified on the basis of method of
dumping the load
• Dump trucks
a) Side or rear dump trucks
b) Bottom dump trucks
• Dumpers
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18. Dumpers
• High speed pneumatic
wheeled trucks
• Short chassis
• Strong bodies
• Loading, hauling and
dumping is done very fast as
compared to other equipment
• Suitable for short hauls on
rough roads
• Specially where a shuttle
movement is required.
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19. CHAPTER-TWO
DOZER
By: Debas D.
19
Ambo University
Department of Mechanical engineering

20. Dozer
• A dozer is a tractor unit which has a substantial
metal plate (known as a blade).
• The blade used to push large quantities of soil,
sand, rubble, or other such material during
construction or conversion work
• Dozers typically equipped at the rear with a claw
like device (known as a ripper) to loosen densely
compacted materials
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21. Applications of dozer
the typical applications of dozer used in many construction
projects are:
 Land clearing
 Dozing (pushing materials)
 Ripping
 Towing other pieces of construction equipment, and
 Assisting scrapers in loading
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22. Dozing
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23. Leveling
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24. Ripping
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25. Land clearing
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26. Assisting scrapers in loading
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27. Types of dozers
1. Crawler type (track laying) tractor
2. Wheel type tractor
a. Single axle
b. Two axle
i. Single axle drive
ii. Two axle drive
Wheel type tractor Crawler type tractor 27

28. Crawler dozer
• A crawler dozer is the machine that travels on
endless chains called tracks driven by sprockets and
has been developed as the most powerful and
compact machine for pulling and pushing of all
purpose.
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29. major components dozer
The major components of dozers are vary among makes, modes, and
configurations.
Figure: Caterpillar D11R dozer
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30. Major components of dozer
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31. Engine
Dozers are powered by diesel engine. The engine provides
power to all operating systems.
figure: The caterpillar D11R diesel engine.
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32. Blades
• The bulldozer blade is a heavy metal plate on the front of the
tractor, used to push objects, and shoving sand, soil and debris.
Universal Blade (U)
• This blade is best for lighter or relatively easily dozed material.
• The large wings on this blade make it the most efficient for
moving large loads over a long distance.
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33. Semi-Universal (SU)
• Semi-Universal blades combine the desirable characteristics
of U-blades and S-blades into one.
• The addition of short wings increases blade capacity.
• The wings provide improved load retention while
maintaining the blade’s ability to penetrate and load quickly
in tightly packed material, and to handle a wide variety of
materials in production applications.
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34. Straight (S)
• Straight blades provide excellent versatility.
• Because they are smaller than SU- or U-blades, they are
easier to maneuver and can handle a wider range of
materials.
• S-blades are more aggressive in penetrating and obtaining
a blade load, They can handle heavy material easily.
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35. Blade- Dozer performance;
Bull dozers pushing potential is measured by two standard
ratios;
1. Horsepower per foot of cutting edge
2. Horsepower per loose cubic yard of material retained in
front of the blade.
 Horsepower per foot (hp/ft) provides an indication of the
ability of the blade to penetrate and obtain a load.
The higher this ratio, the more aggressive the blade.
 Horsepower per loose cubic yard (hp/lcy) measures the
ability to push a load.
A higher ratio means that the bull dozer can push a load
at a greater speed
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36. Blade adjustments
Tilt- the vertical movement of a blade end is known
as tilt. This movement is within the vertical plane of
the blade. Tilting permits concentration of tractor
driving power on limited length of blade.
Tilting
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37. Pitch: The control which allows the operator to vary
the angle of attack of the blade cutting edge with the
ground is a pitch. It is the movement of the top of
the blade toward or away from the tractor.
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38. Angling: Turning the blade so that it is not
perpendicular to the direction of the tractor’s travel is
angling. This causes the pushed material to roll off
the trailing end of; the blade Rolling material off one
end of the blade is called “side casting”.
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39. Undercarriage unit
• Undercarriage units consist of two crawler units
• The driving sprockets is fitted at the rear end while the
idler wheel is fitted at the front end of the frame
• An endless chain passes over the driving sprockets and
the idler wheel and is supported in between by carriers
rollers and track rollers
• Shoes are fitted on the endless chain through out the
length
• The tensioning arrangements is fitted between the
crawler frame and the idler wheel to adjust the chain
sag
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40. BULLDOZERS –TRACKED- OVAL DRIVE
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41. BULLDOZERS –TRACKED-Delta drive
Advantages of delta drive:
• due to elevated engine and drive
risk of getting dust (mud) in is less
• longer operation (life) time
increased bulk clearance
Disadvantages of delta drive:
• higher costs of manufacturing
• more components long crawl belt.
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42. Power flow path on tractor
• Driving power from diesel engine (1) is transmitted to
transmission (4) through main clutch or torque converter
(2) and universal joint (3).
• The power, altered through selection of a proper gear speed
arrangement within the transmission according to load, is
transmitted to bevel pinion (6) at the rear end of the
transmission.
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43. Power flow path on tractor
• The bevel pinion and the bevel gear direct the power into
the right and left directions.
• Steering clutches (7) at both ends left and right of the bevel
gear shaft control the transmission of power from the bevel
gear shaft to the final drive, providing a means for
steering the machine in corporation with brakes (8)
installed on each steering clutch.
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44. • The power from the steering clutch goes to
final drive (9) consisting of a train of gears to
turn sprocket. The sprocket drives track to
cause the machine to travel.
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45. 45

46. Simple Sprocket Drive Operation
• Track drive system also has a drive sprocket that engages a chain used to transmit
drive torque supplied by an engine.
• Turning the sprocket engaged with the track chain pulls the chain that is securely
attached to track shoes. Moving the track shoes produces the crawler-like track
travel to take place.
• The combination of chain and track shoe operates like both a self-laying rail
system and a road for the machine to crawl over.
• The lower rollers on the track frame transfer machine weight to the chain links and
in turn onto the track
in contact with the ground.
• To create a continuous return
of chain to the drive sprocket,
a large idler wheel or idler sprocket is
located opposite to the drive
Sprocket.
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47. Track-Type dozer Steering Systems
Differential Steering Systems
• Track-type machines that use steering clutches and
brakes can only drive one track when they are turning.
This is a big disadvantage when the machine is under
load and trying to make a smooth turn.
• Differential steering action slows down one track and
speeds up the opposite track to make the machine
turn. In other words, it creates a speed differential
between the two tracks. Again, the average speed of
the two tracks is the speed of the machine
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48. • The main components of differential steering systems are the transmission
output pinion, which supplies forward, reverse, and three-speed range inputs
to the system; the planetary differential assembly; a hydraulic steering pump
and motor; and the steering controls.
• The steering motor is controlled by the operator, and as it rotates it turns the
machine left or right.
• The speed of the motor determines how sharp the turn will be, and the
direction the motor turns determines the direction the machine turns.
• In other words, there are two possible inputs to a differential steering system:
the input from a power shift transmission and from the steering motor.
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49. Straight Driving Operation
The transmission pinion drives the drive planetary planet carrier as the input to
the drive planetary; the drive planetary sun gear acts as a held member
because it is attached to the sun gear input for the equalizing planetary, and
therefore the right final drive. The ring gear of the drive planetary then
becomes the output. The drive planetary ring gear is attached to the steering
planetary carrier and to the left final drive. The left final drive is therefore
driven directly by the drive planetary ring gear.
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50. Straight Driving Operation
The pinion gear of the steering motor holds the steering planetary ring gear
stationary. Because the steering planetary carrier is being driven by the drive
planetary ring gear, the steering planetary sun gear becomes the output of the
steering planetary set.
The steering planetary sun gear, the drive planetary sun gear, and the equalizing
planetary sun gear are all connected to the same shaft, so all three sun gears
always turn at the same speed.
The rotation of the sun gear in the drive planetary set reduces the reaction of the
drive carrier’s pinion gears, which are being input from the transmission, and
thereby slows the output of the drive planetary ring gear. The equalizing planetary
sun gear inputs the equalizing planetary gearset. This ring gear of the gearset is
permanently held and can never rotate, and its carrier becomes the output to the
right-side final drive axle. Engineers have designed this system with planetary
gears sized so that, with the three sun gears connected together and the ring gear
output in the drive planetary being slowed by the rotation of the drive planetary
sun gears, the resulting power flows to the pinions of the final drive axles are
equal on both sides of the machine, and the tracks turn at the same speed
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51. Operation While Turning Left or Right
• To turn the machine while it is moving under power, the steering motor rotates
the ring gear of the steering planetary gear set in one direction or the other.
• Rotating the steering ring gear in the same direction as the drive planetary ring
gear, along with the rotation of the steering planetary carriers, slows the output
on the steering differential sun gear, and therefore the input on the equalizing
planetary sun gear, causing the right-side track to slow down.
• The rotation of the ring gear in the same direction of the steering planetary
carrier adds to the carrier’s speed and causes the left-side track to speed up.
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52. • Turning the steering ring gear opposite to the drive planetary ring gear and the
steering planetary carrier causes the steering planetary sun gear to speed up.
Because they are connected, this means that the speed of the drive planetary sun
gear speeds up, which in turn slows down the ring gear output of the drive
planetary and its connected steering planetary carrier, and therefore the left final
drive.
• The equalizing planetary sun gear is also connected to the steering and drive sun
gears, so its speed is increased as well.
• The increased speed on the sun gear inputting the right-side equalizing planetary
gearset causes the equaling carrier and therefore the right-side final drive to speed
up.
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53. 53

54. Hydraulic System
• A dozer blade controlled hydraulically
• The oil is sent to control valve from the gear pump
installed in the hydraulic tank.
• Here the oil pressure is developed for operation the
blade in four position
1. Raise
2. Hold
3. Lower
4. float
• The safety valve is designed to control an abnormal
pressure rise beyond limit and to release the oil into
the tank 54

55. Hydraulic system
• The pressurized oil coming from the gear pump flow into the control
valve after passing through a check valve , which serves to check the
backflow of oil
• A suction valve is provided to suck in make oil from the hydraulic tank
for filling up oil in the hydraulic cylinders.
• For example during the float the piston is lowered by the weight of
the blade and a vacuum is created in the upper chamber s of the
hydraulic cylinders
• The valve draws oil from hydraulic tank to prevent such a negative
pressure with in the cylinders
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56. Hydraulic system
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57. Hydraulic system
• The hydraulic tank is located in front of the
radiator, with in the tank are the gear pump and
control valves
• The oil filter is fitted at the top and the oil drain
plug is fitted at the lower part for draining
purposes.
• The oil strainer is installed with in the oil filter to
prevent entry of dust and dirt into the tank when
the tank is replenished with oil
• The oil level in tank can be checked by the oil
level gauge installed in the oil filter
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