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BULLDOZER

TABLE OF CONTENTS:

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Bulldozer.

History of bulldozer.

Types of dozers.

Dozer uses.

Description.

Dozer primary tools.

blade.

Ripper.

Caterpillar.

Caterpillar d9

Available power

Example

Production of dozer

Example

End.

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A bulldozer is a crawler (continuous tracked tractor) equipped with a substantial metal plate (known as a blade) used to push large

quantities of soil, sand, rubble, or other such material during

construction or conversion work and typically equipped at the rear

with a claw-like device (known as a ripper) to loosen densely-

compacted materials.

The term "bulldozer" is often used erroneously to mean any heavy equipment (sometimes a loader and sometimes an excavator), but

precisely, the term refers only to a tractor (usually tracked) fitted

with a dozer blade. That is the meaning used here

HISTORY

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In 1923, a young farmer named James Cummings and a draftsman named J. Earl McLeod made the first designs for the bulldozer. A

replica is on display at the city park in Morrowville, Kansas where

the two built the first bulldozer. On December 18, 1923

Over the years, bulldozers got bigger and more powerful in response to the demand for equipment suited for ever larger

earthworks.

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Bulldozers can be found on a wide range of sites, mines ( ( and quarries ( ) , military bases, heavy industry factories, engineering projects and farms.

IDF Caterpillar D9R armored bulldozer

TYPE OF DOZERS

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1. Crawler (track laying) tractor.

2. Wheel type tractor.

A.Single axle.

B.Two-axle.

Single axle drive.

Two-axle drive.

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Wheel-type tractor Crawler-type tractor

DOZERS USES

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Typical project applications are:

Land clearing.

Dozing (pushing material)

Ripping.

Towing other pieces of construction equipment's

Assisting scrapers in loading.

DESCRIPTION

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Most often, bulldozers are large and powerful tracked heavy equipment. The tracks give them excellent ground hold and

mobility through very rough terrain. Wide tracks help distribute the

bulldozer's weight over a large area (decreasing pressure), thus

preventing it from sinking in sandy or muddy ground. Extra wide

tracks are known as 'swamp tracks' or "LGP (low ground

pressure)tracks". Bulldozers have excellent ground hold and a

torque divider designed to convert the engine's power into

improved dragging ability. The Caterpillar D9, for example, can

easily tow tanks that weigh more than 70 tons. Because of these

attributes, bulldozers are used to clear areas of obstacles,

shrubbery, burnt vehicles, and remains of structures.

THE BULLDOZER'S PRIMARY

TOOLS

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BLADES

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The bulldozer blade is a heavy metal plate on the front of the tractor, used to push objects, and shoving sand, soil and debris.

DOZER BLADES USUALLY COME IN

FOUR VARIETIES

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o A straight blade ("S blade") which is short and has no lateral curve and no side wings and can be used for fine grading.

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A universal blade ("U blade") which is tall and very curved, and has large side wings to carry more material.

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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.

CUSHION DOZER BLADES

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Cushion Dozers are used to

push load scrapers or track-type tractors.

The heavy duty design includes

a wear-resistant center liner plate and

a reinforced cutting edge section.

Narrow width increases

maneuverability when lining up

for the next pass.

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Blades can be fitted straight across the frame, or at an angle, sometimes using

additional 'tilt cylinders' to vary the angle

while moving. The bottom edge of the

blade can be sharpened, e.g. to cut tree

stumps

BLADE ADJUSTMENTS

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Tilting

BLADE ADJUSTMENTS (CONTD)

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Angle

RIPPER

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The ripper is the long claw-like device on the back of the bulldozer. Rippers can come as a single shank/giant ripper) or in groups of two or more (multi shank rippers). Usually, a single shank is preferred for heavy ripping. The ripper shank is fitted with a replaceable tungsten steel alloy tip.

Ripping rock breaks the ground surface rock or pavement into small rubble easy to handle and transport, which can then be removed so grading can take place.

CATERPILLAR

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The best known maker of bulldozers is probably Caterpillar in the USA, which earned its reputation by making tough, durable,

reliable machines.

Komatsu, JCB and John Deere are present-day competitors. Although these machines began as modified farm tractors, they

became the mainstay for big civil construction projects, and

found their way into use by military construction units worldwide.

The best known model, the Caterpillar D9, was also used to

clear mines and demolish enemy structures.

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The Caterpillar D9 is a large track-type tractor designed and manufactured by Caterpillar Inc. Though it comes in many

configurations it is usually sold as a bulldozer equipped with a

detachable large blade and a rear ripper attachment.

The D9, with 354 kW (474 hp) of gross power and an operating weight of 49 tons, is in the upper end (but not the heaviest), of

Caterpillar's track-type tractors, which range in size from the D3

57 kW (77 hp), 8 tons, to the D11 698 kW (935 hp), 104tons.

The size, durability, reliability, and low operating costs have made the D9 one of the most popular large track-type tractors in the

world.

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Engineering Role: Heavy bulldozer

Propulsion: Caterpillar tracks

Engine model: CAT C18 ACERT (D9T)

3408 HEUI (D9R)

Gross power: 464 hp (346 kW) D9T

474 hp (354 kW) D9R

Flywheel power: 410 hp (306 kW) D9T

410 hp (306 kW) D9R

375 hp (280 kW) D9N

460 hp (343 kW) D9L

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Drawbar pull: 71.6 tons

Operation Weight: 108,000 lbs (48,784 kg)

Length: 26.5 ft (8.1 m)

Width: 14.7 ft (4.5 m) (blade)

Height: 13 ft (4 m)

Speed: 7.3 MPH (11.9 km/h) Forward

9.1 MPH (14.7 km/h) Reverse

Blade capacity: 17.7 yd (13.5 m) 9 SU blade

21.4 yd (16.4 m) 9 U blade

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POWER AVAILABLE

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Empty

Haul

loaded

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Haul

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Haul

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Speed 9 mph

Haul

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Speed 31 mph

Return

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COEFFICIENT OF TRACTION FOR VARIOUS

SURFACES

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surface Rubber-tires Crawler-tracks

Dry, rough concrete 0.80-1 0.45

Dry, clay 0.50-0.70 0.9

Wet, clay 0.4-0.5 0.7

Wet sand and gravel 0.3-0.4 0.35

Loose, dry sand 0.2-0.3 0.3

Dry snow 0.2 0.15-0.35

Ice 0.1 0.1-0.25

Tractive effort (usable force) = coefficient of traction x

weight

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DOZER PRODUCTIVITY

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PRODUCTION FACTORS: DOZERS

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Soil conditions

Angle of swing

Bucket fill

Size

Fill factor

Cycle Time

Job efficiency

Operator

Site condition

Equipment conditions

FIGURE 107. MAXIMUM PRODUCTION RATES FOR DIFFERENT

BULLDOZERS EQUIPPED WITH STRAIGHT BLADE IN RELATION TO HAUL

DISTANCE. (FROM CATERPILLAR HANDBOOK, 1984).

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The graph provides the uncorrected, maximum production. In order to adjust to various conditions which affect production, correction factors are given in

Table 39. Adjustment factors for grade (pushing uphill or downhill) are given

in Figure 108

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Table 39. Job condition correction factors for estimating bulldozer earth

moving production rates. Values are for

track-type tractor equipped straight (S)

blade.

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TRACK TYPE TRACTOR WHEEL TYPE TRACTOR

OPERATOR

Excellent 1.00 1.00

Average 0.75 0.60

Poor 0.60 0.50

MATERIAL

Loose stockpile 1.20 1.20

Hart to cut; frozen--

with tilt cylinder 0.80 0.75

without tilt cylinder 0.70 -

cable controlled blade 0.60 -

Hard to drift; "dead" (dry, non-cohesive material)

or very sticky material 0.80 0.80

SLOT DOZING 0.60 - 0.80 -

SIDE BY SIDE DOZING 1.15 - 1.25 1.15 - 1.25

VISIBILITY --

Dust, rain, snow, fog, darkness 0.80 0.70

JOB EFFICIENCY --

50 min/hr 0.84 0.84

40 min/hr 0.67 0.67

DIRECT DRIVE TRANSMISSION

(0.1 min. fixed time) 0.80 -

BULLDOZER*

Angling (A) blade 0.50 - 0.75 -

Cushioned (C) blade 0.50 - 0.75 0.50 - 0.75

D5 narrow gauge 0.90 -

Light material U-blade (coal) 1.20 1.20

EXAMPLE

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Determine the average hourly production of a 200 hp bulldozer (D7) equipped with a straight blade and tilt

cylinder. The soil is a hard packed clay, the grade is 15

percent favorable, and a slot dozing technique is used.

The average haul or push distance is 30 m. The soil

weight is estimated at 1,200 kg/m3 loose, with a load

factor of 0.769 (30 % swell). An inexperienced operated

is used. Job efficiency is 50 min/hour.

EXAMPLE

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Job efficiency (50 min/hr) 0.84

Poor operator 0.60

Hard to cut soil 0.80

Slot dozing technique 1.20

Weight correction 0.87

The uncorrected maximum production is 430 m3 loose/hour (from

Figure 107) bulldozer curve D7S. Applicable correction factors are:

EXAMPLE

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Production = Maximum Production * Correction Factor

= (430 m3 loose/hr) (0.84) (0.60) (0.80) (1.20) (0.87) = 181 m3 loose/hour

Production (bank m3) = (181 m3 loose/hr) (0.769) = 139 bank m3/hr

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Prepared by :

END

Thank you for your attention