Excavators are heavy construction equipment primarily consisting of a boom , dipper (or stick), bucket , and cab on a rotating platform known as the "house".
88-478: The modern excavator's house sits atop an undercarriage with tracks or wheels , being an evolution of the steam shovel (which itself evolved into the power shovel when steam was replaced by diesel and electric power). All excavation-related movement and functions of a hydraulic excavator are accomplished through the use of hydraulic fluid , with hydraulic cylinders and hydraulic motors , which replaced winches, chains, and steel ropes . Another principle change
176-546: A best practice guide that has been endorsed, inter alia, by the HSE. This provides an alternative route to site safety: adhering to best practice in the use of quick couplers. The market for quick couplers is mainly supplied by a large number of small and medium-sized enterprises. Many of the manufacturers of quick couplers are small, flexible and innovative, leading to the wide variation in design concepts. Many Original Equipment Manufacturers (OEMs) of construction equipment market
264-409: A drive wheel , or drive sprocket , driven by the motor and engaging with holes in the track links or with pegs on them to drive the track. In military vehicles, the drive wheel is typically mounted well above the contact area on the ground, allowing it to be fixed in position. In agricultural crawlers it is normally incorporated as part of the bogie. Placing suspension on the sprocket is possible, but
352-401: A tiltrotator which allows attachments rotate 360 degrees and tilt +/- 45 degrees, in order to increase the flexibility and precision of the excavator. Before the 1990s, all excavators had a long or conventional counterweight that hung off the rear of the machine to provide more digging force and lifting capacity. This became a nuisance when working in confined areas. In 1993 Yanmar launched
440-413: A "thrown" track). Jammed tracks may become so tight that the track may need to be broken before a repair is possible, which requires either explosives or special tools. Multi-wheeled vehicles, for example, 8 X 8 military vehicles, may often continue driving even after the loss of one or more non-sequential wheels, depending on the base wheel pattern and drive train. Prolonged use places enormous strain on
528-564: A Lombard log hauler shipped out to a western state by people who would later build the Phoenix log hauler in Eau Claire, Wisconsin, under license from Lombard. The Phoenix Centipeed typically had a fancier wood cab, steering wheel tipped forward at a 45 degree angle and vertical instead of horizontal cylinders . In the meantime, a gasoline-powered motor home was built by Lombard for Holman Harry (Flannery) Linn of Old Town, Maine to pull
616-872: A backfill (or dozer) blade. This is a horizontal bulldozer-like blade attached to the undercarriage and is used for leveling and pushing removed material back into a hole. As of July 2021, current excavator manufacturers include: [REDACTED] Korea [REDACTED] China [REDACTED] France [REDACTED] United States [REDACTED] Denmark [REDACTED] Sweden [REDACTED] United Kingdom [REDACTED] India [REDACTED] Germany [REDACTED] Russia [REDACTED] [REDACTED] Switzerland-Germany [REDACTED] Iran [REDACTED] Algeria [REDACTED] [REDACTED] [REDACTED] Italy-USA-Netherlands [REDACTED] Indonesia [REDACTED] Turkey Caterpillar track Continuous track or tracked treads are
704-446: A boom, stick and bucket with three joints between them and the house. The boom attaches to the house and provides the up-and-down movement. It can be one of several different configurations: Attached to the end of the boom is the stick (or dipper arm). The stick provides the digging movement needed to pull the bucket through the ground. The stick length is optional depending whether reach (longer stick) or break-out power (shorter stick)
792-411: A closed chain. The links are jointed by a hinge, which allows the track to be flexible and wrap around a set of wheels to make an endless loop. The chain links are often broad, and can be made of manganese alloy steel for high strength, hardness, and abrasion resistance. Track construction and assembly is dictated by the application. Military vehicles use a track shoe that is integral to the structure of
880-509: A continuous track, which he called a "universal railway" in 1825. Polish mathematician and inventor Józef Maria Hoene-Wroński designed caterpillar vehicles in the 1830s to compete with the railways. In 1837, Russian army captain Dmitry Andreevich Zagryazhsky (1807 – after 1860) designed a "carriage with mobile tracks" which he patented the same year, but due to a lack of funds and interest from manufacturers he
968-460: A farmers' exhibition in 1896. Steam traction engines were used at the end of the 19th century in the Boer Wars . But neither dreadnaught wheels nor continuous tracks were used, rather "roll-out" wooden plank roads were thrown under the wheels as required. In short, whilst the development of the continuous track engaged the attention of a number of inventors in the 18th and 19th centuries,
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#17327752888221056-571: A farmers' exhibition in 1896. According to Scientific American , Charles Dinsmoor of Warren, Pennsylvania invented a "vehicle" on endless tracks, patented as No. 351,749 on November 2, 1886. The article gives a detailed description of the endless tracks. Alvin O. Lombard of Waterville, Maine was issued a patent in 1901 for the Lombard Steam Log Hauler that resembles a regular railroad steam locomotive with sled steerage on front and crawlers in rear for hauling logs in
1144-878: A memorandum of 1908, Antarctic explorer Robert Falcon Scott presented his view that man-hauling to the South Pole was impossible and that motor traction was needed. Snow vehicles did not yet exist however, and so his engineer Reginald Skelton developed the idea of a caterpillar track for snow surfaces. These tracked motors were built by the Wolseley Tool and Motor Car Company in Birmingham, tested in Switzerland and Norway, and can be seen in action in Herbert Ponting 's 1911 documentary film of Scott's Antarctic Terra Nova Expedition . Scott died during
1232-567: A merger of the Holt Manufacturing Company and the C. L. Best Tractor Company , an early successful manufacturer of crawler tractors. With the Caterpillar D10 in 1977, Caterpillar resurrected a design by Holt and Best, the high-sprocket-drive, since known as the " High Drive ", which had the advantage of keeping the main drive shaft away from ground shocks and dirt, and is still used in their larger dozers. In
1320-454: A nine-foot steel v-plow and sixteen foot adjustable leveling wings on either side. Once the highway system became paved, snowplowing could be done by four wheel drive trucks equipped by improving tyre designs, and the Linn became an off highway vehicle, for logging , mining , dam construction, arctic exploration , etc. Modern tracks are built from modular chain links which together compose
1408-617: A patent in 1901 and built the first steam-powered log hauler at the Waterville Iron Works in Waterville, Maine, the same year. In all, 83 Lombard steam log haulers are known to have been built up to 1917, when production switched entirely to internal combustion engine powered machines, ending with a Fairbanks diesel-powered unit in 1934. Alvin Lombard may also have been the first commercial manufacturer of
1496-519: A range of quick couplers. Some of these are designed and manufactured by the OEM but more often they are the products of one of the quick coupler manufacturers branded by the OEM and sold through the OEM's distribution chain or installed by the OEM in their factory. In addition to the supply route from the OEMs many distributors of construction machinery will install quick couplers onto machines before delivery at
1584-607: A rear sprocket, the idler wheel is placed higher than the road wheels to allow it to climb over obstacles. Some track arrangements use return rollers to keep the top of the track running straight between the drive sprocket and idler. Others, called slack track , allow the track to droop and run along the tops of large road wheels. This was a feature of the Christie suspension , leading to occasional misidentification of other slack track-equipped vehicles. Continuous track vehicles steer by applying more or less drive torque to one side of
1672-598: A score of engines fitted with dreadnaught wheels. In April 1858, the journal The Engineer gave a brief description of a Clayton & Shuttleworth engine fitted with dreadnaught wheels, which was supplied not to the Western Allies, but to the Russian government for heavy artillery haulage in Crimea in the post-war period. Steam tractors fitted with dreadnaught wheels had a number of shortcomings and, notwithstanding
1760-525: A single bogie that includes the idler-wheel and sometimes the sprocket. Many World War II German military vehicles, initially (starting in the late 1930s) including all vehicles originally designed to be half-tracks and all later tank designs (after the Panzer IV ), had slack-track systems, usually driven by a front-located drive sprocket, the track returning along the tops of a design of overlapping and sometimes interleaved large diameter road wheels, as on
1848-568: A skilled operator to control all four functions simultaneously. The most popular configuration in the US is the SAE controls configuration while in other parts of the world, the ISO control configuration is more common. Some manufacturers such as Takeuchi have switches that allow the operator to select which control configuration to use. Hydraulic excavators now perform tasks well beyond bucket excavation. With
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#17327752888221936-437: A small number of relatively long 'longitudinal' treads. Further to Fowler's patent of 1858, in 1877, a Russian, Fyodor Blinov , created a tracked vehicle called " wagon moved on endless rails". It lacked self-propulsion and was pulled by horses. Blinov received a patent for his "wagon" in 1878. From 1881 to 1888 he developed a steam-powered caterpillar-tractor. This self-propelled crawler was successfully tested and featured at
2024-462: A smaller jockey/drive wheel between each pair of wheels, to support the 'track'. Comprising only eight sections, the 'track' sections are essentially 'longitudinal', as in Boydell's initial design. Fowler's arrangement is a precursor to the multi-section caterpillar track in which a relatively large number of short 'transverse' treads are used, as proposed by Sir George Caley in 1825, rather than
2112-513: 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. Modern continuous tracks can be made with soft belts of synthetic rubber , reinforced with steel wires, in
2200-402: A track laying mechanism, although these designs do not generally resemble modern tracked vehicles. In 1877 Russian inventor Fyodor Abramovich Blinov created a horse-drawn tracked vehicle called " wagon moved on endless rails", which received a patent the next year. In 1881–1888 he created a steam-powered caterpillar-tractor. This self-propelled crawler was successfully tested and showed at
2288-402: A vehicle's cross-country traction, in theory they prevent damage to any pavement. Additionally, the loss of a single segment in a track immobilizes the entire vehicle, which can be a disadvantage in situations where high reliability is important. Tracks can also ride off their guide wheels, idlers or sprockets, which can cause them to jam or to come completely off the guide system (this is called
2376-588: A vehicle's cross-country traction, they prevent damage to any pavement. Some pad systems are designed to remove easily for cross-country military combat . Starting from late 1980s, many manufacturers provide rubber tracks instead of steel, especially for agricultural applications. Rather than a track made of linked steel plates, a reinforced rubber belt with chevron treads is used. In comparison to steel tracks, rubber tracks are lighter, waste less power on internal friction, make less noise and do not damage paved roads. However, they impose more ground pressure below
2464-483: Is flexibility in use in that a machine owner can use a variety of buckets and attachments without changing the quick coupler or buying an adaptor. The claimed advantages of dedicated couplers depend on their individual design but often include better performance and smaller size. The method of operation (the picking up and releasing of buckets and attachments) causes the next divergence in design. The types can be described as manual, semi-automatic, and automatic. Within
2552-537: Is generally smaller, stronger, and has hardened side cutters and teeth used to break through hard ground and rocks. Buckets have numerous shapes and sizes for various applications. There are also many other attachments that are available to be attached to the excavator for boring, ripping, crushing, cutting, lifting, etc. Attachments can be attached with pins similar to other parts of the arm or with some variety of quick coupler . Excavators in Scandinavia often feature
2640-405: Is mechanically more complicated. A non-powered wheel, an idler , is placed at the opposite end of the track, primarily to tension the track, since loose track could be easily thrown (slipped) off the wheels. To prevent throwing, the inner surface of the track links usually have vertical guide horns engaging grooves, or gaps between the doubled road and idler/sprocket wheels. In military vehicles with
2728-458: Is required. Most common is mono stick but there are also, for example, telescopic sticks. The largest form ever of an excavator, the dragline excavator , eliminated the dipper in favor of a line and winch . On the end of the stick is usually a bucket . A wide, large capacity (mud) bucket with a straight cutting edge is used for cleanup and levelling or where the material to be dug is soft, and teeth are not required. A general purpose (GP) bucket
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2816-464: Is retained by his surviving family. Frank Beamond (1870–1941), a less-commonly known but significant British inventor, designed and built caterpillar tracks, and was granted patents for them in a number of countries, in 1900 and 1907. A first effective continuous track was not only invented but really implemented by Alvin Orlando Lombard for the Lombard Steam Log Hauler . He was granted
2904-537: Is slightly more complex, with each link connected to the next by a bushing which causes the track to bend slightly inward. A length of live track left on the ground will curl upward slightly at each end. Although the drive sprocket must still pull the track around the wheels, the track itself tends to bend inward, slightly assisting the sprocket and somewhat conforming to the wheels. Tracks are often equipped with rubber pads to improve travel on paved surfaces more quickly, smoothly and quietly. While these pads slightly reduce
2992-622: Is therefore obvious that the views of the safety authorities of the UK and Australia on what constitutes a safe design are very divergent. In the UK some major construction contractors have written their own specifications for quick couplers allowed on sites under their control. That is, they have pursued site safety via a procurement policy. An alternative approach has been put forward by the Strategic Forum Plant Safety Group . A working party under this group has drawn up
3080-565: The British Army on several occasions between 1905 and 1910, but not adopted. The Hornsby tractors pioneered a track-steer clutch arrangement, which is the basis of the modern crawler operation. The patent was purchased by Holt. The name Caterpillar came from a soldier during the tests on the Hornsby crawler, "trials began at Aldershot in July 1907. The soldiers immediately christened
3168-632: The Crimean War , waged between October 1853 and February 1856, the Royal Arsenal at Woolwich manufacturing dreadnaught wheels. A letter of recommendation was signed by Sir William Codrington, the General commanding the troops at Sebastopol. Boydell patented improvements to his wheel in 1854 (No. 431) – the year his dreadnaught wheel was first applied to a steam engine – and 1858 (No. 356), the latter an impracticable palliative measure involving
3256-457: The UK , wheeled excavators are sometimes known as "rubber ducks". Excavators are used in many ways: Modern hydraulic excavators come in a wide variety of sizes. The smaller ones are called mini or compact excavators . For example, Caterpillar's smallest mini-excavator weighs 2,060 pounds (930 kg) and has 13 hp ; their largest model is the largest excavator available (developed and produced by
3344-505: The arms , swing motor, track motors and accessories while the third is a lower pressure (≈700 psi , 48 bar) pump for pilot control of the spool valves ; this third circuit allows for reduced physical effort when operating the controls. Generally, the 3 pumps used in excavators consist of 2 variable displacement piston pumps and a gear pump. The arrangement of the pumps in the excavator unit changes with different manufacturers using different formats. The three main sections of an excavator are
3432-427: The undercarriage , the house and the arm. The boom, the front part that is attached to the cab itself and holds the arm, is also used. The undercarriage includes tracks, track frame, and final drives, which have a hydraulic motor and gearing providing the drive to the individual tracks. The undercarriage, especially frequently for a mini-excavator, can also have blade similar to that of a bulldozer. The house includes
3520-506: The 70bhp No.2 machine the 'caterpillar'." Holt adopted that name for his "crawler" tractors. Holt began moving from steam to gasoline-powered designs, and in 1908 brought out the 40-horsepower (30 kW) "Holt Model 40 Caterpillar". Holt incorporated the Holt Caterpillar Company, in early 1910, later that year trademarked the name "Caterpillar" for his continuous tracks. Caterpillar Tractor Company began in 1925 from
3608-601: The American Mattracks firm of Minnesota since the mid-1990s. Quick coupler Quick couplers (also called quick hitches ) are used with construction machines to allow the rapid change of working tools or buckets and attachments on the machine. They remove the need to use hammers to manually drive out and insert the mounting pins for attachments. They also bring with them additional safety risks that must be overcome by careful design and manufacture, and proper use. Quick couplers are devices installed at
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3696-725: The Lord Mayor's show in London, and in the following month that engine was shipped to Australia. A steam tractor employing dreadnaught wheels was built at Bach's Birmingham works, and was used between 1856 and 1858 for ploughing in Thetford; and the first generation of Burrell/Boydell engines was built at the St. Nicholas works in 1856, again, after the close of the Crimean War. Between late 1856 and 1862 Burrell manufactured not less than
3784-796: The Northeastern United States and Canada. The haulers allowed pulp to be taken to rivers in the winter. Prior to then, horses could be used only until snow depths made hauling impossible. Lombard began commercial production which lasted until around 1917 when focus switched entirely to gasoline powered machines. A gasoline-powered hauler is on display at the Maine State Museum in Augusta, Maine . After Lombard began operations, Hornsby in England manufactured at least two full length "track steer" machines, and their patent
3872-534: The Orenstein & Koppel, Germany, until the takeover 2011 by Caterpillar, named »RH400«), the CAT 6090, which weighs in excess of 2,160,510 pounds (979,990 kg), has 4500 hp, and a bucket as large as 52.0 m. Hydraulic excavators usually couple engine power to (commonly) three hydraulic pumps rather than to mechanical drivetrains . The two main pumps supply oil at high pressure (up to 5000 psi , 345 bar) for
3960-459: The UK by around October 2008. Safety authorities in other countries have taken a different approach. In Australia the authorities took the view that the problems were caused by designs of quick couplers that did not incorporate a safety pin. That is, they believe that semi-automatics are fundamentally safe. The Australian standard for quick couplers published by Standards Australia , AS 4774 - 2008 therefore does not exclude this design option. It
4048-668: The UK government launched a "safeguard action" under the Machinery Safety Directive (98/37/EC) challenging the validity of the standard and demanding that it be improved. The European Committee for Standardization (CEN) have therefore undertaken to revise the relevant section of the standard. Because of the divergence in design concepts and in opinions on how to manage the associated risks the International Organization for Standardization (ISO) has undertaken to draft an International Standard on
4136-624: The UK, but there are reports of fatalities in Australia, the Republic of Ireland and the USA. The causes of the fatal accidents are not always the same and the views of safety authorities in different countries differ on how to reduce risk. In the UK the Health and Safety Executive (HSE) analysed the accident data and concluded that all of the known fatalities were caused by the operator not inserting
4224-429: The above three categories there are many further divergences in operating principles and detail designs. There are many competing claims relating to the safety and performance benefits and demerits of each design. Fatalities have occurred due to buckets being accidentally released from work equipment during operation. Released buckets have hit bystanders causing fatal injuries. These have been reported in most detail in
4312-493: The advent of hydraulic-powered attachments such as a breaker , a cutter, a grapple or an auger ,a crusher and screening buckets the excavator is frequently used in many applications other than excavation. Many excavators feature a quick coupler for simplified attachment mounting, increasing the machine's utilization on the jobsite. Excavators are usually employed together with loaders and bulldozers . Most wheeled, compact and some medium-sized (11 to 18-tonne) excavators have
4400-451: The case of lighter agricultural machinery . The more common classical type is a solid chain track made of steel plates (with or without rubber pads), also called caterpillar tread or tank tread , which is preferred for robust and heavy construction vehicles and military vehicles . The prominent treads of the metal plates are both hard-wearing and damage resistant, especially in comparison to rubber tyres. The aggressive treads of
4488-433: The chain in order to reduce track weight. Reduced weight allows the vehicle to move faster and decreases overall vehicle weight to ease transportation. Since track weight is completely unsprung , reducing it improves suspension performance at speeds where the track's momentum is significant. In contrast, agricultural and construction vehicles opt for a track with shoes that attach to the chain with bolts and do not form part of
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#17327752888224576-530: The chain's structure. This allows track shoes to break without compromising the ability of the vehicle to move and decrease productivity but increases the overall weight of the track and vehicle. The vehicle's weight is transferred to the bottom length of track by a number of road wheels, or sets of wheels called bogies . While tracked construction equipment typically lacks suspension due to the vehicle only moving at low speeds, in military vehicles road wheels are typically mounted on some form of suspension to cushion
4664-420: The creations of the late 1850s, were never used extensively. In August 1858, more than two years after the end of the Crimean War , John Fowler filed British Patent No. 1948 on another form of "Endless Railway". In his illustration of the invention, Fowler used a pair of wheels of equal diameter on each side of his vehicle, around which pair of toothed wheels ran a 'track' of eight jointed segments, with
4752-567: The damage that their all-steel versions cause to the surface on which they pass: They often cause damage to less firm terrain such as lawns, gravel roads, and farm fields, as the sharp edges of the track easily rout the turf. Accordingly, vehicle laws and local ordinances often require rubberised tracks or track pads. A compromise between all-steel and all-rubber tracks exists: attaching rubber pads to individual track links ensures that continuous track vehicles can travel more smoothly, quickly, and quietly on paved surfaces. While these pads slightly reduce
4840-531: The development of tanks in several countries. The first tanks to go into action, the Mark I , built by Great Britain, were designed from scratch and were inspired by, but not directly based on, the Holt. The slightly later French and German tanks were built on modified Holt running gear. A long line of patents disputes who was the "originator" of continuous tracks. There were a number of designs that attempted to achieve
4928-769: The drive transmission and the mechanics of the tracks, which must be overhauled or replaced regularly. It is common to see tracked vehicles such as bulldozers or tanks transported long distances by a wheeled carrier such as a tank transporter or train , though technological advances have made this practice less common among tracked military vehicles than it once was . The pioneer manufacturers have been replaced mostly by large tractor companies such as AGCO , Liebherr Group , John Deere , Yanmar , New Holland , Kubota , Case , Caterpillar Inc. , CLAAS . Also, there are some crawler tractor companies specialising in niche markets. Examples are Otter Mfg. Co. and Struck Corporation., with many wheeled vehicle conversion kits available from
5016-462: The equipment wagon of his dog & pony show, resembling a trolley car only with wheels in front and Lombard crawlers in rear. Linn had experimented with gasoline and steam-powered vehicles and six-wheel drive before this, and at some point entered Lombard's employment as a demonstrator, mechanic and sales agent. This resulted in a question of proprietorship of patent rights after a single rear-tracked gasoline-powered road engine of tricycle arrangement
5104-604: The expedition in 1912, but expedition member and biographer Apsley Cherry-Garrard credited Scott's "motors" with the inspiration for the British World War I tanks, writing: "Scott never knew their true possibilities; for they were the direct ancestors of the 'tanks' in France." In time, however, a wide array of vehicles were developed for snow and ice, including ski slope grooming machines , snowmobiles , and countless commercial and military vehicles. Continuous track
5192-487: The general use and exploitation of the continuous track belonged to the 20th century, mainly in the United States and England . A little-known American inventor, Henry Thomas Stith (1839–1916), had developed a continuous track prototype which was, in multiple forms, patented in 1873, 1880, and 1900. The last was for the application of the track to a prototype off-road bicycle built for his son. The 1900 prototype
5280-427: The lifting one or other of the driving wheels to facilitate turning. A number of manufacturers including Richard Bach, Richard Garrett & Sons , Charles Burrell & Sons and Clayton & Shuttleworth applied the Boydell patent under licence. The British military were interested in Boydell's invention from an early date. One of the objectives was to transport Mallet's Mortar , a giant 36 inch weapon which
5368-438: The load over the track. The choice of overlapping/interleaved road wheels allowed the use of slightly more transverse-orientation torsion bar suspension members, allowing any German tracked military vehicle with such a setup to have a noticeably smoother ride over challenging terrain, leading to reduced wear, ensuring greater traction and more accurate fire. However, on the Russian front, mud and snow would become lodged between
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#17327752888225456-418: The loader equipment of backhoe-loaders. They are also occasionally installed on attachments installed on agricultural tractors . Quick couplers do not normally have a specific function themselves in that they do not carry out handling or digging operations, but when installed on a machine they become a part of the overall system. They are usually mounted on the machine by means of the pins that would otherwise be
5544-546: The mountings for the bucket or attachment. This article concentrates on quick couplers installed on excavators and similar equipment. There are many variations in the design of quick couplers. The initial divergence is between those that can pick up any of a range of buckets and attachments by clamping onto the mounting pins for the attachment (known as "pin grabbers" or "pin couplers") and those that work only with buckets and attachments designed to suit that quick coupler (known as "dedicated"). The claimed advantage of pin-grabbers
5632-456: The operator cab, counterweight , engine, fuel and hydraulic oil tanks. The house attaches to the undercarriage by way of a center pin. High-pressure oil is supplied to the tracks' hydraulic motors through a hydraulic swivel at the axis of the pin, allowing the machine to slew 360° unhindered and thus provides the left-and-right movement. The arm provides the up-and-down and closer-and-further (or digging movement) movements. Arms typically consist of
5720-403: The outer end of the work equipment of various types of construction and earth-moving machines . They facilitate the rapid exchange of working tools or buckets. Quick couplers are most common on hydraulic excavators and compact excavators and on the backhoe equipment of backhoe loaders , but are also installed on telescopic handlers , wheel loaders (loading shovels), skid-steer loaders and
5808-485: The overlapping wheels, freeze, and immobilize the vehicle. As a tracked vehicle moves, the load of each wheel moves over the track, pushing down and forward that part of the earth or snow underneath it, similarly to a wheeled vehicle but to a lesser extent because the tread helps distribute the load. On some surfaces, this can consume enough energy to slow the vehicle down significantly. Overlapped and interleaved wheels improve performance (including fuel consumption) by loading
5896-422: The production between 1917 and 1952, approximately 2500 units, was sold directly to highway departments and contractors. Steel tracks and payload capacity allowed these machines to work in terrain that would typically cause the poorer quality rubber tyres that existed before the mid-1930s to spin uselessly, or shred completely. Linn was a pioneer in snow removal before the practice was embraced in rural areas, with
5984-406: The request of a customer. Quick coupler manufacturers will also sell direct to end-users and usually complete the installation as part of the sale. A European standard in place since 1996 gives some guidance on the safety of quick couplers (EN474-1). However, this standard is unclear in many aspects leading to uncertainty as to whether semi-automatic couplers comply with it or not. Because of this
6072-568: The ride over rough ground. Suspension design in military vehicles is a major area of development; the very early designs were often completely unsprung. Later-developed road wheel suspension offered only a few inches of travel using springs, whereas modern hydro-pneumatic systems allow several feet of travel and include shock absorbers . Torsion-bar suspension has become the most common type of military vehicle suspension. Construction vehicles have smaller road wheels that are designed primarily to prevent track derailment and they are normally contained in
6160-493: The right to produce vehicles under his patent. At about the same time a British agricultural company, Hornsby in Grantham , developed a continuous track which was patented in 1905. The design differed from modern tracks in that it flexed in only one direction, with the effect that the links locked together to form a solid rail on which the road wheels ran. Hornsby's tracked vehicles were given trials as artillery tractors by
6248-479: The safety of quick couplers. This project is being undertaken by Technical Committee 127 (ISO TC/127) . A Working Group was set up to draft the standard, which will be reviewed internationally through normal ISO procedures and will be published as ISO 13031 . This work will probably be completed in 2013. The intention in Europe is that, subject to the standard being suitable, the ISO standard would then be adopted as
6336-491: The safety pin in semi-automatic couplers. Even without the safety pin inserted the buckets would not have been released unless there had been a failure of some part of the mechanism, or some error in operation by the operator. The HSE concluded that the most effective way to reduce the risk of further accidents was for semi-automatic couplers to be withdrawn from sale. The suppliers of these couplers agreed to this voluntarily so semi-automatic couplers were withdrawn from sale in
6424-531: The suspension systems of the Tiger I and Panther tanks, generically known by the term Schachtellaufwerk (interleaved or overlapping running gear) in German, for both half-track and fully tracked vehicles. There were suspensions with single or sometimes doubled wheels per axle, alternately supporting the inner and outer side of the track, and interleaved suspensions with two or three road wheels per axle, distributing
6512-420: The track more evenly. It also must have extended the life of the tracks and possibly of the wheels. The wheels also better protect the vehicle from enemy fire, and mobility is improved when some wheels are missing. This relatively complicated approach has not been used since World War II ended. This may be related more to maintenance than to original cost. The torsion bars and bearings may stay dry and clean, but
6600-456: The tracks provide good traction in soft surfaces but can damage paved surfaces, so some metal tracks can have rubber pads installed for use on paved surfaces. Other than soft rubber belts, most chain tracks apply a stiff mechanism to distribute the load equally over the entire space between the wheels for minimal deformation, so that even the heaviest vehicles can move easily, just like a train on its straight tracks. The stiff mechanism
6688-522: The tractor crawler. At least one of Lombard's steam-powered machines apparently remains in working order. A gasoline-powered Lombard hauler is on display at the Maine State Museum in Augusta. In addition, there may have been up to twice as many Phoenix Centipeed versions of the steam log hauler built under license from Lombard, with vertical instead of horizontal cylinders. In 1903, the founder of Holt Manufacturing, Benjamin Holt , paid Lombard $ 60,000 for
6776-410: The vehicle than the other, and this can be implemented in a variety of ways. Tracks may be broadly categorized as live or dead track. Dead track is a simple design in which each track plate is connected to the rest with hinge-type pins. These dead tracks will lie flat if placed on the ground; the drive sprocket pulls the track around the wheels with no assistance from the track itself. Live track
6864-413: The wheels and tread work in mud, sand, rocks, snow, and other surfaces. In addition, the outer wheels (up to nine of them, some double) had to be removed to access the inner ones. In WWII, vehicles typically had to be maintained for a few months before being destroyed or captured , but in peacetime, vehicles must train several crews over a period of decades. Transfer of power to the track is accomplished by
6952-539: The wheels, as they are not able to equalize pressure as well as the stiff mechanism of track plates, especially the spring loaded live tracks. Another disadvantage is that they are not disassemblable into tracks and therefore cannot be repaired, having to be discarded as whole if once damaged. Previous belt-like systems, such as those used for half-tracks in World War II, were not as strong, and during military actions were easily damaged. The first rubber track
7040-454: The world's first Zero Tail Swing excavator, which allows the counterweight to stay inside the width of the tracks as it slews, thus being safer and more user friendly when used in a confined space. This type of machine is now widely used throughout the world. There are two main types of control configuration used in excavators to control the boom and bucket, each distributing the four primary digging functions across two x-y joysticks. This allows
7128-481: Was built to replace the larger motor home in 1909 on account of problems with the old picturesque wooden bridges. This dispute resulted in Linn departing Maine and relocating to Morris, New York, to build an improved, contour following flexible lag tread or crawler with independent suspension of halftrack type, gasoline and later diesel powered. Although several were delivered for military use between 1917 and 1946, Linn never received any large military orders. Most of
7216-470: Was first applied to a military vehicle on the British prototype tank Little Willie . British Army officers, Colonel Ernest Swinton and Colonel Maurice Hankey , became convinced that it was possible to develop a fighting vehicle that could provide protection from machine gun fire. During World War I , Holt tractors were used by the British and Austro-Hungarian armies to tow heavy artillery and stimulated
7304-429: Was first given a physical form by Hornsby & Sons in 1904 and then made popular by Caterpillar Tractor Company , with tanks emerging during World War I . Today, they are commonly used on a variety of vehicles, including snowmobiles , tractors , bulldozers , excavators and tanks . The idea of continuous tracks can be traced back as far as the 1830s, however. The British polymath Sir George Cayley patented
7392-400: Was invented and constructed by Adolphe Kégresse and patented in 1913; in historic context rubber tracks are often called Kégresse tracks . First rubber-tracked agricultural tracked was Oliver Farm Equipment HGR in 1945-1948, which was ahead of its time and only seen small-scale production. The disadvantages of tracks are lower top speed, much greater mechanical complexity, shorter life and
7480-408: Was later purchased by Holt in 1913, allowing Holt to claim to be the "inventor" of the crawler tractor. Since the "tank" was a British concept it is more likely that the Hornsby, which had been built and unsuccessfully pitched to their military, was the inspiration. In a patent dispute involving rival crawler builder Best, testimony was brought in from people including Lombard, that Holt had inspected
7568-413: Was the direction of the digging action, with modern excavators pulling their buckets toward them like a dragline rather than pushing them away to fill them the way the first powered shovels did. Excavators are also called diggers, scoopers, mechanical shovels, or 360-degree excavators (sometimes abbreviated simply to "360"). Tracked excavators are sometimes called "trackhoes" by analogy to the backhoe . In
7656-532: Was unable to build a working prototype, and his patent was voided in 1839. Although not a continuous track in the form encountered today, a dreadnaught wheel or "endless railway wheel" was patented by the British Engineer James Boydell in 1846. In Boydell's design, a series of flat feet are attached to the periphery of the wheel, spreading the weight. A number of horse-drawn wagons, carts and gun carriages were successfully deployed in
7744-557: Was under development, but, by the end of the Crimean War, the mortar was not ready for service. A detailed report of the tests on steam traction, carried out by a select Committee of the Board of Ordnance, was published in June 1856, by which date the Crimean War was over, consequently the mortar and its transportation became irrelevant. In those tests, a Garrett engine was put through its paces on Plumstead Common. The Garrett engine featured in
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