A large bulldozer with multi-tine ripper, the Caterpillar D9
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.
Typically, bulldozers are large and powerful trackedheavy 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
Bulldozer bladeKomatsu bulldozer pushing up to 7 m with semi-U tilt dozer
Bulldozer blades come in three types:
straight ("S blade"), short with no lateral curve or side wings. Can be used for fine grading.
universal ("U blade"), tall and very curved, with large side wings to maximize load.
combination ("S-U", or semi-U), shorter, with less curvature and smaller side wings. It is typically used for pushing large rocks, as at a quarry.
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".
Multishank ripperA Caterpillar D10N bulldozer equipped with a single-shank ripper
A 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 tungstensteelalloy 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
A tracked loader is designed to transport rather than push or rough-grade material
Further informationon the small airborne bulldozer: Clark CA1
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
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]
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.
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
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
A 19th-century term used in engineering for a horizontal forging press
Around 1870s: In the USA, a "bulldose" was a large dose (namely, one large enough to be literally or figuratively effective against a bull) of any sort of medicine or punishment.
By the late 1870s, "to bulldoze" and "bulldozing" were being used throughout the United States to describe intimidation "by violent and unlawful means",[14] which sometimes meant a severe whipping or coercion, or other intimidation, such as at gunpoint.[15] It had a particular meaning in the Southern United States as a whipping or other punishment for African Americans to suppress black voter turnout in the 1876 United States presidential election.[16][17][18]
1886: "Bulldozer" meant a large-caliber pistol and the person who wielded it.[15]
Late 19th century: "Bulldozing" meant using brute force to push over or through any obstacle, with reference to two bulls pushing against each other's heads in a fight over dominance.[15]
1930s: applied to the vehicle
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".
Athanas for the 'bulldozer shrimp' (from the way it pushes sand about)
Land scraper or land leveler - an earth moving machine that is pulled behind a tractor rather than pushed.
Related Research Articles
A military engineering vehicle is a vehicle built for construction work or for the transportation of combat engineers on the battlefield. These vehicles may be modified civilian equipment or purpose-built military vehicles. The first appearance of such vehicles coincided with the appearance of the first tanks, these vehicles were modified Mark V tanks for bridging and mine clearance. Modern military engineering vehicles are expected to fulfill numerous roles, as such they undertake numerous forms, examples of roles include; bulldozers, cranes, graders, excavators, dump trucks, breaching vehicles, bridging vehicles, military ferries, amphibious crossing vehicles, and combat engineer section carriers.
Continuous track or tracked treads are a system of vehicle propulsion used in tracked vehicles, running on a continuous band of treads or track plates driven by two or more wheels. The large surface area of the tracks distributes the weight of the vehicle better than steel or rubber tyres on an equivalent vehicle, enabling continuous tracked vehicles to traverse soft ground with less likelihood of becoming stuck due to sinking.
A tractor is an engineering vehicle specifically designed to deliver a high tractive effort at slow speeds, for the purposes of hauling a trailer or machinery such as that used in agriculture, mining or construction. Most commonly, the term is used to describe a farm vehicle that provides the power and traction to mechanize agricultural tasks, especially tillage, and now many more. Agricultural implements may be towed behind or mounted on the tractor, and the tractor may also provide a source of power if the implement is mechanised.
The Caterpillar D9 is a large track-type tractor designed and manufactured by Caterpillar Inc. It is usually sold as a bulldozer equipped with a detachable large blade and a rear ripper attachment.
Excavators are heavy construction equipment primarily consisting of a boom, dipper, bucket and cab on a rotating platform known as the "house" - although the largest form ever, the dragline excavator, eliminated the dipper in favor of a line and winch.
A loader is a heavy equipment machine used in construction to move or load materials such as soil, rock, sand, demolition debris, etc. into or onto another type of machinery.
A backhoe loader, also called a loader backhoe, loader excavator, tractor excavator, digger or colloquially shortened to backhoe within the industry, is a heavy equipment vehicle that consists of a tractor-like unit fitted with a loader-style shovel/bucket on the front and a backhoe on the back. Due to its (relatively) small size and versatility, backhoe loaders are very common in urban engineering and small construction projects as well as developing countries. This type of machine is similar to and derived from what is now known as a TLB (Tractor-Loader-Backhoe), which is to say, an agricultural tractor fitted with a front loader and rear backhoe attachment.
Heavy equipment, heavy machinery, earthmovers, construction vehicles, or construction equipment, refers to heavy-duty vehicles specially designed to execute construction tasks, most frequently involving earthwork operations or other large construction tasks. Heavy equipment usually comprises five equipment systems: the implement, traction, structure, power train, and control/information.
A grader, also commonly referred to as a road grader, motor grader, or simply blade, is a form of heavy equipment with a long blade used to create a flat surface during grading. Although the earliest models were towed behind horses, and later tractors, most modern graders are self-propelled and thus technically "motor graders".
The Caterpillar D11T is a large bulldozer introduced by Caterpillar Inc. in 1986 to replace its D10. Weighing 248,500 pounds (112,700 kg), it is Caterpillar's largest and most powerful bulldozer. Mainly used in the mining industry, it is also employed to push-load scrapers, and rip rock overburden. D11s are manufactured in East Peoria, Illinois.
The Caterpillar D6 track-type tractor is a medium bulldozer manufactured by Caterpillar Inc. with a nominal operating weight of 18 short tons (16 t). The military versions were classified as the SNL G152 medium tractor, under the G-numbers classification system used for army tractors.
The Komatsu D575A is a 1,150 horsepower (860 kW) tractor crawler produced in a 'SR' or Super Ripper bulldozer/ripper configuration, or as a dedicated bulldozer in the form of the 'SD' or Super Dozer. Both models can move 90 cubic yards (69 m3) of material per pass using the standard blade. The D575A-3 SD Super Dozer can move 125 cubic yards (96 m3) of material per pass if equipped with an optional blade. The D575A-3 can dig to a maximum depth of 6 feet 9 inches (2.06 m) using its single-shank ripper.
In civil engineering, a wheel tractor-scraper is a type of heavy equipment used for earthmoving. It has a pan/hopper for loading and carrying material. The pan has a tapered horizontal front cutting edge that cuts into the soil like a carpenter's plane or cheese slicer and fills the hopper which has a movable ejection system. The horsepower of the machine, depth of the cut, type of material, and slope of the cut area affect how quickly the pan is filled.
The Caterpillar D10 is a bulldozer manufactured by Caterpillar Inc. between 1977 and 1987, when it was superseded by the D11. It was the first modern tractor to use the elevated drive sprocket to improve durability, operator comfort, and ease of maintenance.
The armored bulldozer is a basic tool of combat engineering. These combat engineering vehicles combine the earth moving capabilities of the bulldozer with armor which protects the vehicle and its operator in or near combat. Most are civilian bulldozers modified by addition of vehicle armor/military equipment, but some are tanks stripped of armament and fitted with a dozer blade. Some tanks have bulldozer blades while retaining their armament, but this does not make them armored bulldozers as such, because combat remains the primary role — earth moving is a secondary task.
A compact or mini excavator is a tracked or wheeled vehicle with an approximate operating weight from 0.7 to 8.5 tonnes. It generally includes a standard backfill blade and features independent boom swing.
The Caterpillar D7 is a medium track-type tractor manufactured by Caterpillar Inc. and most commonly used as a bulldozer.
Traxcavator was a namebrand of the Trackson Company of Milwaukee, Wisconsin. The word "Traxcavator" came from combining "tractor" and "excavator".
The Oliver OC-9 was the first tractor crawler by Oliver Farm Equipment Company to employ the use of a torque converter. Along with the OC-96 variant, this model was introduced in 1959 as the final model in the OC series, marking a significant advancement in the company's technological standards.
Prior to and during World War II the United States Army called several tractors M1 Light Tractor. Under the Ordnance Corps these commercial off-the-shelf tractors were meant to tow artillery pieces so were not equipped with blades like their Engineer counterparts. Eventually these were replaced by purpose built "High Speed Tractors" (HST). Some tractors were equipped with crane attachments for ammunition, and material handling.
References
↑ Trewhitt, Philip (1999). Armoured Fighting Vehicles. Dempsey-Parr. ISBN1-84084-328-4.
↑ Tréguer, Pascal (19 February 2018). "Original Meaning of 'bulldozer': A Racist Bully". Word Histories. Retrieved 13 March 2022. The noun bulldozer is first recorded in 1876, in the plural, in the sense of Southern members or supporters of the Democratic Party who colluded to disenfranchise African-American voters; after the American Civil War (1861-65), the 15th Amendment to the Constitution, ratified on 3rd February 1870, granted Afro-American men the right to vote ... The bulldozers, also known as regulators, used threats and acts of violence in order to prevent Afro-American voters from casting their ballots for candidates of the Republican Party.
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