A bulldozer or dozer (also called a crawler) is a large, motorized machine equipped with a metal blade to the front for pushing material: soil, sand, snow, rubble, or rock during construction work. It travels most commonly on continuous tracks, though specialized models riding on large off-road tires are also produced. Its most popular accessory is a ripper, a large hook-like device mounted singly or in multiples in the rear to loosen dense materials.
Bulldozers are used heavily in large and small scale construction, road building, minings and quarrying, on farms, in heavy industry factories, and in military applications in both peace and wartime.
The word "bulldozer" refers only to a motorized unit fitted with a blade designed for pushing. The word is sometimes used inaccurately for other heavy equipment such as a front-end loader designed for carrying rather than pushing material. The term originally referred only to the blade attachment but is now commonly applied to any crawler tractor with a front mounted blade.
Description
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A Liebherr bulldozer with a straight bladeThe same bulldozer's multishank ripperTypically, bulldozers are large and powerful tracked heavy equipment. The tracks give them excellent traction and mobility through very rough terrain. Wide tracks also help distribute the vehicle's weight over a large area (decreasing ground pressure), thus preventing it from sinking in sandy or muddy ground. Extra-wide tracks are known as swamp tracks or low ground pressure (lgp) tracks. Bulldozers have transmission systems designed to take advantage of the track system and provide excellent tractive force.
These traits allow bulldozers to excel in road building, construction, mining, forestry, land clearing, infrastructure development, and any other projects requiring highly mobile, powerful, and stable earth-moving equipment.
A variant is the all-wheel-drive wheeled bulldozer, which generally has four large rubber-tired wheels, hydraulically operated articulated steering, and a hydraulically actuated blade mounted forward of the articulation joint.
The bulldozer's primary tools are the blade and the ripper:
Blade
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Bulldozer blade Komatsu bulldozer pushing up to 7 m3 with semi-U tilt dozerBulldozer blades come in three types:
Blades can be fitted straight across the frame, or at an angle. All can be lifted, some, with additional hydraulic cylinders, can be tilted to vary the angle up to one side.
Sometimes, a bulldozer is used to push or pull another piece of earth-moving equipment known as a "scraper" to increase productivity. The towed Fresno Scraper, invented in 1883 by James Porteous, was the first design to enable this to be done economically, removing the soil from an area being cut and depositing where needed as fill. Dozer blades with a reinforced center section for pushing are known as "bull blades".
Dozer blades are added to combat engineering vehicles and other military equipment, such as artillery tractors such as the Type 73 or M8 Tractor, to clear battlefield obstacles and prepare firing positions.[1] Dozer blades may be mounted on main battle tanks to clear antitank obstacles or mines, and dig improvised shelters.
Ripper
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Multishank ripper A Caterpillar D10N bulldozer equipped with a single-shank ripperA ripper is a long, claw-like shank that may be mounted singly or in multiples on the rear of a bulldozer to loosen hard and impacted materials. Usually a single shank is preferred for heavy ripping. The ripper is equipped with a replaceable tungsten steel alloy tip, known as a boot.
Ripping can not only loosen soil (such as podzol hardpan) in agricultural and construction applications but break shaly rock or pavement into easily handled small rubble.
A variant of the ripper is the stumpbuster,[2] a single spike protruding horizontally used to split a tree stump.
Variants
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A tracked loader is designed to transport rather than push or rough-grade materialFurther information on the small airborne bulldozer: Clark CA1
Armored bulldozers
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Bulldozers employed for combat-engineering roles are often fitted with armor to protect the driver from firearms and debris, enabling bulldozers to operate in combat zones. The most widely documented use is the Israeli Military militarized Caterpillar D9, for earth moving, clearing terrain obstacles, opening routes, and detonating explosive charges. The IDF used armoured bulldozers extensively during Operation Rainbow where they were used to uproot Gaza Strip smuggling tunnels and destroy residential neighbourhoods, water wells and pipes, and agricultural land[3][4] to expand the military buffer zone along the Philadelphi Route.[4] This use drew criticism against both the use and the suppliers of armoured bulldozers from human-rights organizations such as the EWASH-coalition and Human Rights Watch,[5][6] the latter of whom urged Caterpillar to cease their sale of bulldozers to the IDF. The use of bulldozers was seen as necessary by Israeli authorities to uproot smuggling tunnels, destroy houses used by Palestinian gunmen, and expand the buffer zone.[4][7]
Some forces' engineer doctrines differentiate between a low-mobility armoured dozer (LMAD) and a high-mobility armoured dozer (HMAD). The LMAD is dependent on a flatbed to move it to its employment site, whereas the HMAD has a more robust engine and drive system designed to give it road mobility with a moderate range and speed. HMADs, however, normally lack the full cross-country mobility characteristics of a dozer blade-equipped tank or armoured personnel carrier.
Some bulldozers have been fitted with armor by civilian operators to prevent bystanders or police from interfering with the work performed by the bulldozer, as in the case of strikes or demolition of condemned buildings. This has also been done by civilians with a dispute with the authorities, such as Marvin Heemeyer, who outfitted his Komatsu D355A bulldozer with homemade composite armor to then demolish government buildings.
Remote-controlled dozers
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In recent years, innovations in the construction technology have made remote-controlled bulldozers a reality. Now, heavy machinery can be controlled from up to 1,000 feet away. This contributes to the safety of workers on the jobsite, keeping them at a secure distance from potentially dangerous jobs.
The advancement and the ability to control the heavy machinery from afar provides workers with the sufficient control over the dozers to get the job done. Though these machines are still in their early stages, many construction companies are using them successfully.[citation needed]
History
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The first bulldozers were adapted from Holt farm tractors that were used to plough fields. The versatility of tractors in soft ground for logging and road building contributed to the development of the armored tank in World War I.
In 1923, farmer James Cummings and draftsman 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.[8] On December 18, 1923, Cummings and McLeod filed U.S. patent #1,522,378 that was later issued on January 6, 1925, for an "Attachment for Tractors."[9]
By the 1920s, tracked vehicles became common, particularly the Caterpillar 60. Rubber-tired vehicles came into use in the 1940s. To dig canals, raise earthen dams, and do other earth-moving jobs, these tractors were equipped with a large, thick, metal plate in front. (The blade got its curved shape later). In some early models, the driver sat on top in the open without a cabin. The three main types of bulldozer blades are a U-blade for pushing and carrying soil relatively long distances, a straight blade for "knocking down" and spreading piles of soil, and a brush rake for removing brush and roots. These attachments (home-built or built by small equipment manufacturers of attachments for wheeled and crawler tractors and trucks) appeared by 1929.
Widespread acceptance of the bull-grader does not seem to appear before the mid-1930s. The addition of power down-force provided by hydraulic cylinders instead of just the weight of the blade made them the preferred excavation machine for large and small contractors alike by the 1940s, by which time the term "bulldozer" referred to the entire machine and not just the attachment.
Over the years, bulldozers got bigger and more powerful in response to the demand for equipment suited for ever larger earthworks. Firms such as Caterpillar, Komatsu, Clark Equipment Co, Case, Euclid,[10] Allis Chalmers, Liebherr, LiuGong, Terex, Fiat-Allis, John Deere, Massey Ferguson, BEML, XGMA, and International Harvester manufactured large, tracked-type earthmoving machines. R.G. LeTourneau and Caterpillar manufactured large, rubber-tired bulldozers.
Bulldozers grew more sophisticated as time passed. Improvements include drivetrains analogous to (in automobiles) an automatic transmission instead of a manual transmission, such as the early Euclid C-6 and TC-12 or Model C Tournadozer, blade movement controlled by hydraulic cylinders or electric motors instead of early models' cable winch/brake, and automatic grade control. Hydraulic cylinders enabled the application of down force, more precise manipulation of the blade, and automated controls.
In the very snowy winter of 1946–47 in the United Kingdom, in at least one case a remote cut-off village running out of food was supplied by a bulldozer towing a big sled carrying necessary supplies.
A more recent innovation is the outfitting of bulldozers with GPS technology, such as manufactured by Topcon Positioning Systems, Inc., Trimble Inc, or Leica Geosystems, for precise grade control and (potentially) "stakeless" construction. As a response to the many, and often varying claims about these systems, the Kellogg Report[11] published in 2010 a detailed comparison of all the manufacturers' systems, evaluating more than 200 features for dozers alone.
The best-known maker of bulldozers is Caterpillar. Komatsu, Liebherr, Case, Hitachi, Volvo, 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.
Manufacturers
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Industry statistics based on 2010 production published by Off-Highway Research showed Shantui was the largest producer of bulldozers, making over 10,000 units that year or two in five crawler-type dozers made in the world.[12] The next-largest producer by number of units is Caterpillar Inc., which produced 6,400 units.[12]
Komatsu introduced the D575A in 1981, the D757A-2 in 1991, and the D575A-3 in 2002, which the company touts as the biggest bulldozer in the world.[13]
History of the word
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These appeared as early as 1929, but were known as "bull grader" blades, and the term "bulldozer blade" did not appear to come into widespread use until the mid-1930s. "Bulldozer" now refers to the whole machine, not just the attachment. In contemporary usage, "bulldozer" is sometimes shortened to "dozer", and the verb "bulldozing" to "dozing", thus making a homophone with the pre-existing verb "dozing".
Gallery
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See also
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References
Updated December 26th, 2022
Also called a crawler or a bulldozer, dozers are heavy equipment often used for large-scale construction and mining projects. Fitted with a blade on the front and a ripper on the back, dozers are powerful demolition and pushing machines.
They are used mainly for excavation, digging, leveling, and earthmoving projects including pushing large amounts of heavy materials like snow, rock, sand, dirt, and more. As the front of a bulldozer has a blade rather than a bucket, they're not as great at material handling as other equipment like skid steers, backhoes, wheel loaders, or even excavators.
Bulldozers move on heavy metal tracks which makes them ideal for rough terrain. Because of these tracks, crawlers should not be used on finished concrete or asphalt.
The CAT D5K dozer, now more commonly referred to as the CAT D3 dozerPopular construction sites that dozers are used for include the early stages of road building, land clearing like removing rubble, rocks, or debris, fine grading, or ground leveling. These crawlers are also great for other forms of heavy-duty maintenance like snow plowing and tearing up asphalt.
There are different kinds of dozers that will impact the choice you make: there are standard track-width dozers as well as low-ground pressure dozers, also known as wide-track dozers. When working in soft-ground environments, you'll want an LGP dozer to prevent any sinking or chance of getting stuck.
Bulldozers can be used for a variety of different construction projects. Since their large flat blades can be used to push and move large amounts of dirt or rock, dozers are often seen in a variety of commercial and large-scale industries such as construction, mining, and farming. The heaviness of what the machine can push will change based on the dozer's specs.
A bulldozer can also be used with other pieces of heavy equipment to effectively and efficiently complete a project. The bulldozer is a great addition to any excavation project and is often used alongside backhoes or excavators to move the excavated materials around.
Aside from pushing around dirt and soil, bulldozers can be used to clear brush and waste using the ripper on the back. They are also used often on landfill projects due to their ability to push around heavy loads. Lastly, bulldozers can also be used to grade surfaces, rip out trees, and grind down rocks.
The ability to change the blade type adds versatility and multifunctionality to the bulldozer.
While not the best machine for lifting and material handling, fitting the dozer with the right blade can help the machine become more efficient. There are several blade types including straight blades (S-blades), universal blades (U-blades), Semi-U (S-U-blades), and Angle Blades.
S-blades are wingless blades used for high-density materials like mud, stumping, or grading. U-blades are more curved and have wings making them better options for jobs like ditching, hauling, or pushing where more loose materials like dirt or sand will be found.
S-U-blades are less curved than U-blades and have smaller wings but are great for heavier materials. Angle blades allow for the blade to push materials to angles up to 30 degrees and are best for granular materials like snow or gravel. The S-U-blade is the most commonly used one.
Lastly, there are Power-Angle-Tilt blades or PAT blades. These blades provide the most versatility because they can tilt, angle, and lift in every direction. PAT blades are used for backfilling, leveling, land clearing, spreading, scraping, and grading projects.
Beyond blades, dozers can also be fitted with rakes. For example, root rakes are a great attachment when doing large-scale land clearing that can take out bushes and roots while leaving any of the soil behind.
The rippers on the back of a bulldozer are used to break down rock or hard surfaces and make them easier to move.
The most common way to refer to bulldozers is through their specs including model number, operating weight, and horsepower. There are also typically three sizes of dozers: small, medium, and large.
Small bulldozers are machines between 15,000 lbs and 25,000 lbs, medium dozers are between 25,000 lbs and 100,000 lbs, and large dozers are any machine above 100,000 lbs. The horsepower range of these machines is typically less than 100 hp for small, between 100 and 400 hp for medium, and above 400 hp for large.
The John Deere 550K dozer would be considered a small dozerThere are only a few manufacturers to consider when looking to buy or rent a dozer. Many modern bulldozers have state-of-the-art technology built into them like grade technology or increased load-carrying performance. However, the strength of the machine will depend on different dozer specs, sizes, and models.
A variety of bulldozer rentals are available on DOZR including machines ranging from 15,000 lbs up to 200,000 lbs. The following is a look at some more popular brands of bulldozer suppliers.
Caterpillar is one of the most recognized brands of heavy equipment and machinery. Within their bulldozer portfolio, they make 18 models including the small D1, D2, and D3 dozers, their medium Cat bulldozers, the D4, D5, D6, D6XE, D7, and D8 dozers, and their large crawlers including the D9, D10T2 (Tier 4 Final), and D11 dozer, which is the biggest Cat dozer at 229,800 lbs. There is no D12 dozer currently.
For their specs, Caterpillar dozers range between 80 to 105 hp and 15,000 lbs to 20,000 lbs for the small dozers, 130 to 350 hp and 29,000 to 88,000 lbs for the medium dozers, and 450 to 800 hp and 100,000 lbs to 250,000 lbs for the large crawlers.
Previously, Caterpillar models were titled the D3K, D4K, D5K, D6K, D6N, and D7E. This range has become what is now known as the D1 to D6.
The CAT D4K crawler. This model is now referred to as the D2 dozer.Caterpillar does also have some wheeled dozers including the 814, 824K, 834K, 844K, and 854K models.
Designed with performance, efficiency, comfort, and reliability in mind, Liebherr bulldozers offer a variety of different options. Liebherr doesn't produce any standard small crawler tractors as the Liebherr 716 and 726 dozers, their two smallest models, have operating weights between 29,000 lbs to 46,000 lbs.
The Liebherr 776 dozer is their largest dozer with an operating weight of 161,354 lbs and 757 horsepower.
One of the world’s leading suppliers and manufacturers of heavy equipment, Komatsu dozers are anything but little. Manufacturing equipment for several different industries, Komatsu bulldozers are made for industries like construction, mining, quarrying, forestry, and compact construction. Komatsu dozer sizes are also filtered by small, medium, and large.
For their small crawlers, they make 10 models ranging from 19,842 lbs to 31,438 lbs. They also have 16 medium bulldozers ranging from 41,094 lbs to 53,000 lbs and 11 large bulldozers ranging from 68,530 lbs to 120,970 lbs. Lastly, they have industry-specific machines including their surface mining dozers, the D375 and D475, which are 163,340 lbs and 254,195 lbs respectively.
The Komatsu 39EX dozer pushing dirt on a job site.The D475 is Komatsu's largest dozer.
Growing from what was originally just a plow, John Deere dozers offer a large variety of heavy equipment. The smallest John Deere bulldozer is the 450 dozer coming in at 18,752 lbs and 80 horsepower. Their largest crawler dozer is the John Deere 1050 with a weight of 96,000 lbs and 350 hp, making it quite a bit smaller than other manufacturers on this list.
The John Deere 700k dozer on a road work project.In between the John Deere 450 dozer and 1050, they also have the 550, 650, 700, 750, 850, and 950 dozers. There also used to be the John Deere 350 dozer but that has been discontinued and bought used.
The last supplier we're going to cover in this blog is Case. Case dozers include 6 models: the 650M, 750M, 850M, 1150M, 1650M, and 2050M. They also previously had the Case 450 dozer, but this was discontinued.
The smallest Case bulldozer, the 650M, has an operating weight of around 16,000 lbs and 68 horsepower. The largest Case dozer, the 2050M, has an operating weight of 49,000 lbs and 218 horsepower, making their models only in the small and medium ranges.
Looking for a dozer rental? You can rent a bulldozer from DOZR Marketplace. Models and availability may vary depending on location.
Operating any kind of heavy equipment could pose a safety hazard and dozers are no exception. It is important to always be careful and to only operate a piece of heavy equipment after receiving proper training. Bulldozers are incredibly powerful machines and incorrect usage can create a dangerous situation.
We have a full guide to safety tips for dozer operators, but here's a short list as well:
Use the handrails and steps to get into the bulldozer and maintain three points of contact. Never take another route to the cab.
Latch down any external areas like the ripper or climbing ladder.
Travel at slow speeds, especially in heavy traffic areas or in rough terrains where it's harder to control the machine
Make sure to start from the bottom when working on a hill and use the machine on a diagonal
Take the time to fully turn off the equipment when leaving the cab of a dozer. This can ensure that the machine is stable and won’t move.
Always check the blind spots and use a spotter if needed
Provide any upkeep needed - tracks that are too tight can lead to unnecessary repairs and maintenance
In the United States, OSHA – Occupational Safety and Health Administration – does not provide certifications for heavy equipment operation but does require an employer to provide training and instruction. Any employee tasked with the operation of heavy equipment must receive training in:
OSHA mandates that only employees with proper training from their company may operate the equipment.
The most important point to remember for any operation of heavy equipment is to only do so if this training has been provided and it is safe to do so. Always request training before agreeing to operate a piece of new machinery. Put safety first and take training protocols seriously.