Bulldozers use blades attached to the front to push objects and level land. There are several types of blades including straight blades for grading, universal blades for moving loose materials, and angle blades for sidecasting. Blades are attached to the bulldozer and can be pitched, tilted, or angled using hydraulic cylinders. Bulldozers also have an undercarriage with tracks or wheels and a transmission system to power the movement of the machine and operation of the blade. Regular maintenance includes inspecting blades, hydraulic systems, and transmission components.

1. Bulldozer

2. Bulldozer
• A bulldozer is a crawler mounted tractor equipped
with a substantial metal plate known as a blade
attached in front
• Consist of a tractor with a front mounted blade
controlled by hydraulic cylinders use for different
cut for different depth & leveling as per condition
of land.

3. classification of bulldozers:
• On the basis of blade control
1. cable controlled or
2. hydraulic controlled
• Depending upon mountings
I. crawler tractor mounted bulldozers
II. Wheel tractor mounted bulldozers
• Depending on nature of blade:
I. Front casting dozer(straight) or bulldozer
II. Angle dozer
III. Tilt dozer
• In case of front casting dozer blade is fixed perpendicular to the direction
of travel. The balde at right angel to the longitudinal axis of tractor. In
case of front casting dozer it moves earth in the forward direction.
• In case if Angle dozer the blade is fixed at an angle with the direction of
travel. In case of Angle dozer it moves earth one side in the forward
direction

7. front casting dozer

12. Dozer Blades
• A dozer blade consists of a moldboard with
replaceable cutting edges and side
• bits. Push arms and tilt cylinders or a C-frame
connect the blade to the dozer
• The bulldozer blade is a heavy metal plate on the
front of the tractor, used to push objects, and
shove sand, soil and debris. Blades can be fitted
straight across the frame, or at an angle,
sometimes using additional 'tilt cylinders' to vary
the angle while moving

15. • A Straight Blade ("S-Blade") which is short and has no lateral curve, no
side wings, and can be used for fine grading.
• A Universal Blade ("U-Blade") which is tall and very curved, and has large
side wings to carry more material.
• An Angling Blade (Angle blade or angle dozer.) which is lower, straight
across the face, has a very curved profile designed to roll material in front
of it and has the ability to be angled to either side to facilitate movement
of material across the machine's path in front of the blade. The angling
blade is w i d e r than a straight or semi-U blade to allow for angling
across the machine.
• A "Semi-U" combination blade which is shorter, has less curvature, and
smaller side wings. This blade is typically used for pushing piles of large
rocks, such as at a quarry.
• In recent years, adaptations of the angling blade have featured power
angling and power side-to-side tilting of the blade on the move by the use
of hydraulic rams. These blades are commonly called 'power angle and
tilt' (PAT) blades and are most commonly fitted to smaller crawlers used
for clean-up and finishing work.

17. Bulldozer blade classification
• Dozer blades usually come in three varieties:
• A straight blade ("S blade") which is short and has
no lateral curve and no side wings and can be used
for fine grading.
• A universal blade ("U blade") which is tall and very
curved, and has large side wings to carry more
material.
• An "S-U" combination blade which is shorter, has
less curvature, and smaller side wings. This blade is
typically used for pushing piles of large rocks, such
as at a quarry.

18. Straight Blade
• Designed for short- and medium distance passes, such as
backfilling, grading, and spreading fill material.
• Blades have no curvature across their length and are
mounted in a fixed position, perpendicular to the dozer's line
of travel
• Generally, a straight blade is heavy-duty and normally it can
be tilted, within a 10° arc, increasing penetration for cutting
or decreasing penetration for back dragging material.
• It may be equipped to pitch to set one end of the cutting
edge deeper into the ground to dig or pry hard materials.
• For easy drifting of light materials, the edge's are brought to
the same level-the blade is level in the horizontal plane.

19.  Designed for short- and medium distance
passes, such as backfilling, grading, and
spreading fill material.
 Blades have no curvature across their
length and are mounted in a fixed
position, perpendicular to the dozer's line
of travel.
8 October 2013 Mansoor Azam Qureshi 19
 Generally, a straight blade is heavy-duty and normally it can be
tilted, within a 10° arc, increasing penetration for cutting or
decreasing penetration for back dragging material.
 It may be equipped to pitch to set one end of the cutting edge
deeper into the ground to dig or pry hard materials.
 For easy drifting of light materials, the edge's are brought to
the same level-the blade is level in the horizontal plane.

20.  An angle blade is wider (face length)
by 1 to 2 ft than an S blade.
 It can be angled up to a maximum of
25° left or right of perpendicular to
the tractor or held perpendicular to
the dozer's line of travel.
 The blade can be tilted.
 It cannot be pitched.
 The angle blade is very effective for
side-casting material, particularly
for backfilling or making side hill
cuts.
8 October 2013 Mansoor Azam Qureshi 20

21.  This blade is wider than a straight blade.
 Outside edges are canted forward about
25°reducesing the spillage of loose.
 The cutting ratio is lower for the U than
the S blade mounted on a similar dozer.
 The U blade's load ratio is lower than
that of a similar S blade.
 The blade is best suited for lighter
materials.
 Typical usages are working stockpiles
and drifting loose or non cohesive
materials.
8 October 2013 Mansoor Azam Qureshi 21

22.  This blade combines
the characteristics
of the S and U-blade
designs.
 By the addition of
short wings it has
increased capacity
compared to an S
blade.
8 October 2013 Mansoor Azam Qureshi 22

23.  Cushion blades are mounted on large dozers that
are used primarily for push-loading scrapers.
 The C blade is shorter than the S blade so as to
avoid pushing the blade into and cutting the rear
tires of the scraper while push-loading.
 The shorter length also facilitates maneuvering
into position behind the scrapers.
 Rubber cushions and springs in the mounting
enable the dozer to absorb the impact of
contacting the scraper push block.
 By using a cushion blade instead of a "pusher
block" to push scrapers, the dozer has the ability
to clean up the cut area and increase the total
fleet production.
 It is a blade of limited utility in pushing material
and should not be used for production dozing.
 It cannot be tilted, pitched, or angled.
8 October 2013 Mansoor Azam Qureshi 23

24. Angle Blade
• An angle blade is wider (face length) by 1 to 2 ft than an S blade.
• It can be angled up to a maximum of 25° left or right of perpendicular to the
tractor or held perpendicular to the dozer's line of travel.
• The blade can be tilted.
• It cannot be pitched.
• The angle blade is very effective for side-casting material, particularly for
backfilling or making side hill cuts.

25. Universal Blade
• This blade is wider than a straight blade.
• Outside edges are canted forward about 25°reducesing the spillage
of loose.
• The cutting ratio is lower for the U than the S blade mounted on a
similar dozer.
• The U blade's load ratio is lower than that of a similar S blade.
• The blade is best suited for lighter materials.
• Typical usages are working stockpiles and drifting loose or non
cohesive materials.

26. Semi Universal Blade
• This blade combines the characteristics of the
S and U-blade designs.
• By the addition of short wings it has increased
capacity compared to an S blade.

27. Cushion Blade
• Cushion blades are mounted on large dozers that are
used primarily for push-loading scrapers.
• The C blade is shorter than the S blade so as to avoid
pushing the blade into and cutting the rear tires of the
scraper while push-loading.
• The shorter length also facilitates maneuvering into
position behind the scrapers.

28. Dozer Blade Operation
 The design of some machines enables either
end of the blade to be raised or lowered in
the vertical plane of the blade.
 Pitching
 Tilting
 Angling

29. Pitching of Blade
• This is a pivotal
movement about the
point of connection
between the dozer
and blade. When the
top of the blade is
pitched forward, the
bottom edge moves
back; this increases
the angle of cutting
edge attack.
8 October 2013 Mansoor Azam Qureshi 29

30. Pitching of Blade
• This is a pivotal movement about the point of
connection between the dozer and blade. When the
top of the blade is pitched forward, the bottom edge
moves back; this increases the angle of cutting edge
attack

32. Angling of Blade
• Turning the blade so that it is not
perpendicular to the direction of the dozer's
travel is known as angling. Angling causes the
pushed material to roll off the trailing end of
the blade. This procedure of rolling material
off one end of the blade is called side casting.

34. Tilting of Blade
• This movement is within the vertical plane of
the blade. Tilting permits concentration of
dozer driving power on a limited portion of
the blade's length.

35. CONSTRUCTION OD DOZER
• A DOZER CONSIST OF FOLLOWINGS
COMPONENTS
1. BLADE
2. ARMS
3. UNDERCARRIAGE UNIT
4. TRANSMISSION SYSTEM
5. BLADE OPERATION SYSTEM

36. BLADE
• A dozer blade consists of a moldboard with replaceable cutting edges and
side bits. Push arms and tilt cylinders or a C-frame connect the blade to the
dozer
• A dozer blade consists of a moldboard with replaceable cutting edges and
side bits. Either the push arms and tilt cylinders or a C-frame are used to
connect the blade to the tractor. Blades vary in size and design based on
specific work applications. The hardened-steel cutting edges and side bits are
bolted on because they receive most of the abrasion and wear out rapidly. This
allows for easy replacement. Machine designs allow either edge of the blade
to be raised or lowered in the vertical plane of the blade (tilt).
• The top of the blade can be pitched forward or backward varying the angle
of attack of the cutting edge (pitch). Blades mounted on a C-frame can be
turned from the direction of travel (angling). These features are not
applicable to all blades, but any two of these features may be incorporated
in a single mount.

37. • Most push arms are attached to the bottom of the winches
.blade and to the outside of the track frame at the trunnion
Dozer Blades
• On dozers equipped with an angle blade, the-push arms are a “C”
frame configuration. The “C”A dozer blade cutting edge and corner
bits are bolted frame is attached to the trunnions and wraps around
theto the bottom of the blade . Remember, front of the dozer.
The blade is attached to the “C” pin

38. ARMS
• Arms provided in dozers are made of two parts
1. push arms
2. pitch arms
• push arm;- they are hollow beams connected from hinge points of the body to
the bottom of the blade .
• They are usually mounted on the out side track frame and In so design where the
frames are fixed on the inside of the track frame
• Pitch arm;- they are diagonal bracing members placed between the push arm and
top of the blade. They provided support when the load is above the line of push
arm.
• They also help in controlling the pitch and tilt of the blade
• They are either single piece member or two piece members
• Two piece members help in lengthening and shortening the pitch arms there by
helping in forward and backward tipping

39. Undercarriage unit
• Undercarriage units consist of two crawler units
mounted on the frames
• 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

40. shoes
track
tensioneridler guide (pilot) wheel
driving wheel
crawler belt runners
pinsOval drive
1.2.3.1. BULLDOZERS –TRACKED- OVAL DRIVE
Mini Bulldozer

41. 1.2.3.1. 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, longer crawler belt.

42. 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, longer crawler belt.
1.2.3.1. BULLDOZERS –TRACKED-Delta drive

43. Power transmission• Power delivered from the engine is distributed for the travelling of the machine
and for the engine is delivered to the main gear box through the main clutch
and a an usually mounted on the outside track frame.
• However there are some designs' where the frames are fixed on the inside of
the track frame intermediate brake
• The gear box has two output shafts one is power take off shaft to drive the cable
control unit and other drives a bevel gear shaft , which in turn drives two
sprockets through steering clutch and reduction gear box

44. Power transmission
• For running auxiliary components like steering
pump , main clutch pump , power control unit and
drive shaft , power is taken through a suitable
gearing arrangements
• The machine is steered by controlling the steering
clutches individually. During the forward motion of
the machine both the steering clutches are fully
engaged, while the steering clutches at the left
and the right are engaged or disengaged
accordingly to turn left or right

45. 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

46. 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

47. • 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
Hydraulic system

48. Dozer maintenance
• Types
1. Component wise maintenance
2. Hourly(preventing)

49. Component wise maintenance
• Blades and arms
1. Any material sticking on the front wall should be scrapped
2. The edge of the blade should be inspected for sharpness
3. Corner piece should be secured properly
4. Hinge point of both push arm and pitch arm should be
inspected for any play and properly lubricated
• Blade operation control unit
1. Inspect for any leakage of hydraulic hose , oil seals etc
2. Inspect smooth operation of blade lifting cylinders
3. Lean Inspect operation of safety valve , locking valves etc
4. Clean and replace oil strainers

50. Component wise maintenance
• Transmission system
1. Operate the main clutch to test proper functioning
2. Inspect the intermediate brake by applying it
3. Transmission gear box oil level should be checked
4. Gear box bearing should be inspected
5. Functioning of steering clutches should be inspected
6. Driving sprockets should be checked
• Undercarriage unit
1. The shoes and its profile should be checked
2. Excessive sagging of chain should be corrected
3. Inspect the conditions of the track and carrier rollers
4. Tighten different mountings and bolts

51. Daily Maintenance
• Check engine crank case, main clutch and steering clutch
case oil levels and add if necessary.
• Record engine oil pressure (a) at idle condition, and (b) at
full rpm load.
• Clean air cleaner element.
• Drain oil from the fuel oil filter and the final tank sump.
• Check radiator coolant level and add if necessary.
• Check linkage.
• Check operator’s report.
• Check floating seals for any sign of oil leakage.
• Check wiring for discontinuity, shorting or loose terminals.
• Check mounting bolts and nuts.

52. 100 hours maintenance of dozer
• Repeat daily maintenance
• Change engine oil
• Change engine oil filter element
• Lubricate generator
• Clean front tank breather
• Check air system and its connections.
• Check electrolyte level in the batteries.
• Check trubo charge clearance: (i) Redial 5 to 33
thousandth of an inch, (ii) End play 6 to 19
thousandth of an inch.

53. 200 hours maintenance of dozer
• Repeat 100 hours maintenance.
• Lubricate cranking motor.
• Change engine oil bypass filter element.
• Check corrosion register.
• Check engine coolant
• Check and adjust belt tension
• Change fuel filter element
• Replace air cleaner element
• Check operator’s report
• Check and correct oil level in the final drive case and hydraulic tank.
• Check steering clutch oil filter element
• Check and tighten loose track shoe mounting bolts.

54. 400 hours
• Repeat 200 hours maintenance.
• Clean fuel pump screen and magnet
• Check fan drive pulley.
• Check generator and cranking motor.
• Steam and clean radiator fins.
• Check and clean radiator fins
• Change cooling fluid.

55. 800 hours
1. Repeat 400 hours maintenance.
2. Adjust injector valves.
3. Tighten manifolds nuts and cap screw.

56. 1800 hours
1. Repeat 800 hours maintenance.
2. Change oil of the following units.
3. main clutch case, (ii) steering clutch case (iii) final drive
case, and (iv) hydraulic tank
4. check alternator and steering motor.
5. Clean main clutch case oil strainer
6. Drain fuel float tank
7. Flush cooling carriage components
8. Check undercarriage components.
9. Clean the inside of the fuel tank.
•

57. Selection of dozer blade
• Properly matching a tractor to a dozer blade is
essential for maximizing production. Blade choice is
dependent on the
1. limitations of the tractor,
2. the characteristics of the material being moved,
such as: Particle Size and Shape -. Voids -. Water
Content -

58. 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.
Applications include land reclamation, stockpile work,
charging hoppers, trapping for loaders, overburden removal,
landfill, and stockpiling of coal and woodchip piles.

59. Semi-Universal (Semi-U
SU-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. Equipped with a
push plate,it can be effective for pushloading scrapers.

60. Straight (S) - Straight blades
• 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, plus they can
handle heavy material easily.

62. Vijay Kumar
Lecturer in Mining Engg.
Govt. Polytechnic –Bicholim-Goa