BULLDOZER
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TABLE OF CONTENTS: 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 denselycompacted 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
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HISTORY • 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 ( (المناجمand quarries )(المحاجر, military bases, heavy industry factories, engineering projects and farms.
IDF Caterpillar D9R armored bulldozer 5
TYPE OF DOZERS 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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Crawler-type tractor
Wheel-type tractor 7
DOZERS USES Typical project applications are: Land clearing. Dozing (pushing material)
Ripping. Towing other pieces of construction equipment's
Assisting scrapers in loading.
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DESCRIPTION • 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. 9
THE BULLDOZER'S PRIMARY TOOLS
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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.
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DOZER BLADES USUALLY COME IN FOUR VARIETIES 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.
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CUSHION DOZER BLADES • 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
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BLADE ADJUSTMENTS • Tilting
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BLADE ADJUSTMENTS (CONT’D) • Angle
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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.
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CATERPILLAR • 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. 22
• 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 23
• 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 yd³ (13.5 m³) 9 SU blade
• 21.4 yd³ (16.4 m³) 9 U blade
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POWER AVAILABLE
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Haul Empty
loaded
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Haul
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Haul
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Haul
Speed 9 mph
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Return
Speed 31 mph
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COEFFICIENT OF TRACTION FOR VARIOUS SURFACES 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 • Soil conditions • Angle of swing • Bucket fill • Size • Fill factor
• Cycle Time • Job efficiency •
Operator
• Site condition • Equipment conditions
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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
1.00 0.60
1.00 0.60 0.50
1.20
1.20
0.80 0.60
0.75 -
0.80
0.80
0.60 - 0.80 1.15 - 1.25
1.15 - 1.25
0.80
0.70
0.84 0.67
0.84 0.67
0.80
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0.50 - 0.75
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Cushioned (C) blade
0.50 - 0.75
0.50 - 0.75
D5 narrow gauge
0.90
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OPERATOR Excellent Average Poor MATERIAL Loose stockpile Hart to cut; frozen-with tilt cylinder without tilt cylinder cable controlled blade Hard to drift; "dead" (dry, non-cohesive material) or very sticky material SLOT DOZING SIDE BY SIDE DOZING VISIBILITY -Dust, rain, snow, fog, darkness JOB EFFICIENCY -50 min/hr 40 min/hr DIRECT DRIVE TRANSMISSION (0.1 min. fixed time) BULLDOZER* Angling (A) blade
0.75
0.70
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EXAMPLE • 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.
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EXAMPLE The uncorrected maximum production is 430 m3 loose/hour (from Figure 107) bulldozer curve D7S. Applicable correction factors are:
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
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EXAMPLE
• 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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END Thank you for your attention
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