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Continuous track

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.

Continuous tracks on a bulldozer
An agricultural tractor with rubber tracks, mitigating soil compaction
A Russian tracked vehicle designed to operate on snow and swamps
A British Army Challenger 1 tank

Modern continuous tracks can be made with soft belts of synthetic rubber, reinforced with steel wires, in 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,[1] 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 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 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.

History edit

The British polymath Sir George Cayley patented a continuous track, which he called a "universal railway" in 1825.[2] Polish mathematician and inventor Józef Maria Hoene-Wroński designed caterpillar vehicles in the 1830s to compete with the railways.[3] 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 was unable to build a working prototype, and his patent was voided in 1839.

Heathcote's Steam Plough edit

 
Heathcote Steam Plough as demonstrated in 1837

Patented in 1832 by John Heathcoat (also Heathcote) M.P. for Tiverton, the Heathcote steam plough was demonstrated in 1837 and press coverage fortunately provided a wood cut of this unusual tracked vehicle.[4] The continuous tracks were made of 215 cm (7 ft) sections of wood bolted to continuous iron bands which were driven by the 'drums' at each end. A strong chassis provided the bearings for the drums, and carried the steam engine, fuel and winch. The chassis was supported on "numerous small wheels or rollers" which ran upon the lower iron bands, which "thus form a perfectly portable and smooth road for the platform". The drums were 275 or 305 cm (9 or 10 ft) in diameter, 790 cm (26 ft) apart. The tracks were each 215 cm (7 ft) wide with a 215 cm (7 ft) gap in-between giving an overall width of 640 cm (21 ft). The twin-cylinder steam engine could be used either to drive the plough winch or to drive the vehicle along, at a speed of up to 150 cm/min (5 ft/min). Although the machine weighed 30 tons complete with 6 tons of fuel, its ground pressure was only 869 kg/m2 (178 lb/sq ft), considerably less than a man. The successful demonstration was carried out on Red Moss at Bolton-le-Moors on 20 April 1837. The steam plough was lost when it sank into a swamp by accident and was then abandoned as the inventor did not have the funds to continue development.[5][6]

Dreadnaught wheel by Boydell (1846) edit

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.[7] A number of horse-drawn wagons, carts and gun carriages were successfully deployed in 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.[8][9]

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 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 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,[10] 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 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.[11]

Between late 1856 and 1862 Burrell manufactured not less than 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.[12][13][14] Steam tractors fitted with dreadnaught wheels had a number of shortcomings and, notwithstanding the creations of the late 1850s, were never used extensively.[9][15]

Endless Railway by John Fowler (1858) edit

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 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.[16] 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,[17] rather than 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".[18] 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 a farmers' exhibition in 1896.[18]

20th century efforts edit

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.[19] In short, whilst the development of the continuous track engaged the attention of a number of inventors in the 18th and 19th centuries, 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.[20][21] The last was for the application of the track to a prototype off-road bicycle built for his son.[1] The 1900 prototype 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.[22]

 
Lombard Steam Log Hauler (Designed, patented 1901)

First commercial success (1901) edit

A first effective continuous track was not only invented but really implemented by Alvin Orlando Lombard for the Lombard Steam Log Hauler.[citation needed] He was granted 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 the tractor crawler.[citation needed]

At least one of Lombard's steam-powered machines apparently remains in working order.[23] 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 the right to produce vehicles under his patent.[citation needed]

The stiff chain by Hornsby & Sons (1904) edit

At about the same time a British agricultural company, Hornsby in Grantham, developed a continuous track which was patented in 1905.[24] 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 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.[citation needed] The patent was purchased by Holt.[citation needed]

Holt and the Caterpillar edit

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 the 70bhp No.2 machine the 'caterpillar'."[25] 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.[26]

Caterpillar Tractor Company began in 1925 from 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",[27] which had the advantage of keeping the main drive shaft away from ground shocks and dirt,[28] and is still used in their larger dozers.

Snow vehicles edit

In 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.[30] Snow vehicles did not yet exist however, and so his engineer Reginald Skelton developed the idea of a caterpillar track for snow surfaces.[31] 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.[32] Scott died during 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."[33]

 
Skid-steer snow-wing and snow pusher with tracked treads

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.

Military application edit

Continuous track 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.[34]

During World War I, Holt tractors were used by the British and Austro-Hungarian armies to tow heavy artillery and stimulated 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.

Patent history edit

A long line of patents disputes who was the "originator" of continuous tracks. There were a number of designs that attempted to achieve a track laying mechanism, although these designs do not generally resemble modern tracked vehicles.[35][36][37]

In 1877 Russian inventor Fyodor Abramovich Blinov created a horse-drawn tracked vehicle called "wagon moved on endless rails",[18] 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 a farmers' exhibition in 1896.[18]

According to Scientific American, Charles Dinsmoor of Warren, Pennsylvania invented a "vehicle" on endless tracks, patented as No. 351,749 on November 2, 1886.[38][39] The article gives a detailed description of the endless tracks.[40]

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 the Northeastern United States and Canada.[citation needed] 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 was later purchased by Holt in 1913, allowing Holt to claim to be the "inventor" of the crawler tractor.[41] 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 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.[citation needed] The Phoenix Centipeed typically had a fancier wood cab, steering wheel tipped forward at a 45 degree angle and vertical instead of horizontal cylinders.

Linn edit

In the meantime, a gasoline-powered motor home was built by Lombard for Holman Harry (Flannery) Linn of Old Town, Maine to pull 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 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 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.[citation needed]

Linn was a pioneer in snow removal before the practice was embraced in rural areas, with 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.[citation needed]

Engineering edit

Construction and operation edit

Modern tracks are built from modular chain links which together compose 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.[42]

Track construction and assembly is dictated by the application. Military vehicles use a track shoe that is integral to the structure of 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 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 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 a single bogie that includes the idler-wheel and sometimes the sprocket.

Overlapping road wheels edit

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 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 the load over the track.[43]

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 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 the track more evenly. It also must have extended the life of the tracks and possibly of the wheels.[citation needed] 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 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[citation needed], but in peacetime, vehicles must train several crews over a period of decades.

Drive train edit

Transfer of power to the track is accomplished by 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 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 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.

Steering edit

Continuous track vehicles steer by applying more or less drive torque to one side of the vehicle than the other, and this can be implemented in a variety of ways.

"Live" and "dead" track edit

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 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.

Rubber track pads edit

Tracks are often equipped with rubber pads to improve travel on paved surfaces more quickly, smoothly and quietly. While these pads slightly reduce 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.

Rubber tracks edit

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 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 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.

Advantages edit

  • Tracks are much less likely to get stuck in soft ground, mud or snow since they distribute the weight of the vehicle over a larger contact area, decreasing its ground pressure: The seventy-ton M1 Abrams tank has an average ground pressure of just over 15 psi (100 kPa). Since tyre air pressure is approximately equal to average ground pressure, a typical car will have an average ground pressure of 28 psi (190 kPa) to 33 psi (230 kPa).
  • Tracked vehicles have better mobility over rough terrain than those with wheels: They smooth out the bumps, glide over small obstacles and are capable of crossing trenches or breaks in the terrain: Riding in a fast tracked vehicle feels just like riding in a boat over heavy swells.
  • The larger contact area, coupled with the cleats, or grousers, on the track shoes, allows vastly superior traction that results in a much better ability to push or pull large loads where wheeled vehicles would dig in. Bulldozers, which are most often tracked, use this attribute to rescue other vehicles, (such as wheel loaders) which have become stuck in, or sunk into, the ground.
  • Tracks cannot be punctured or torn and are more resistant in military combat. Should a track be broken, it often can be repaired immediately using some special tools and spare parts, without the need for special facilities, which might be crucial in combat situations.

Disadvantages edit

 
A JSDF Type 10 with a thrown track

The disadvantages of tracks are lower top speed, much greater mechanical complexity, shorter life and 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 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 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 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[citation needed].

Gallery edit

Current manufacturers edit

The pioneer manufacturers have been replaced mostly by large tractor companies such as AGCO, Liebherr Group,[44] John Deere, Yanmar, New Holland, Kubota,[45] Case, Caterpillar Inc., CLAAS.[46] Also, there are some crawler tractor companies specialising in niche markets. Examples are Otter Mfg. Co. and Struck Corporation.,[47] with many wheeled vehicle conversion kits available from the American Mattracks firm of Minnesota since the mid-1990s.

Russian off-road vehicles are built by companies such as ZZGT[48] and Vityaz.[49]

In nature edit

  • Navicula diatoms are known for their ability to creep about on each other and on hard surfaces such as microscope slides. It is thought that around the outside of the navicula's shell is a girdle of protoplasm that can flow and thus act as a tank track.

See also edit

References edit

  1. ^ a b "The Tank Tread Was His Baby". Popular Science (June): 63. 1944. from the original on 2017-03-13. Retrieved 2011-08-24.
  2. ^ "Sir George Cayley's patent universal railway". Mechanics Magazine. 5 (127): 225–227. 1826-01-28. from the original on 2017-03-13.
  3. ^ "Josef-Maria Hoëné de Wronski". from the original on 2009-08-11. Retrieved 2009-05-30.
  4. ^ "Heathcote's Steam Plough". Chelmsford Chronicle. US. 29 December 1837. p. 4.
  5. ^ Classic Caterpillar Crawlers. MotorBooks International. 2001. ISBN 9781610605793.
  6. ^ Brown, Jonathan (2008). Steam on the Farm: A History of Agricultural Steam Engines 1800 to 1950. Crowood Press. ISBN 9781847970527.
  7. ^ "Burrell's traction engine with Boydell's endless railway". Grace's Guide. 1857. from the original on 2013-10-02. Retrieved 2013-09-30.
  8. ^ Lane, Michael R. (1994). The story of the St. Nicholas Works: A History of Charles Burrell and Sons. London: Unicorn Press. ISBN 978-0906290071.
  9. ^ a b "Boydell Artillery Wheel" (PDF). (PDF) from the original on 2013-10-02. Retrieved 2013-09-30.
  10. ^ "Governments Experiments with Boydell's Traction-Engine". The Farmer's Magazine. London. 45 (1). 1856-06-30. from the original on 2016-03-04.
  11. ^ "Tuxford's Boydell Traction Engine" (PDF). Science& Society: Picture Library. UK. 1857. (PDF) from the original on 2016-03-04. Retrieved 2014-02-04.
  12. ^ (Staff) (23 April 1858). "The iron, coal, and general trades of Birmingham, Wolverhampton, and other towns". The Engineer. 5: 327–328. See p. 328, left-hand column.
  13. ^ Lane (1994).
  14. ^ Clark, Ronald H. (1974). The Development of the English Traction Engine. Cambridge UK: Goose and Son. ISBN 0900404027.
  15. ^ "Charles Burrell & Sons Limited" (PDF). University of Reading. UK. (PDF) from the original on 2014-02-21. Retrieved 2013-09-30.
  16. ^ "Burrell-Boydell Tractor" (PDF). (PDF) from the original on 2013-10-02. Retrieved 2013-09-30.
  17. ^ Caley, Georg (1825). "Patent No. 5260 A New Locomotive Apparatus" (PDF). (PDF) from the original on 2017-11-21. Retrieved 2013-09-30.
  18. ^ a b c d Lozovoi, D.; Lozova, A. "Изобретатель трактора (Ф. Блинов)" [The inventor of the tractor (F.Blinov)]. Russia in Colours (in Russian). from the original on 2011-07-27. Retrieved 2011-08-24.
  19. ^ The Implement and Machinery Review, 1901-01-02
  20. ^ Henry T. Stith's patents for tracked wheels:
    • Stith, Henry T. "Improvement in traction-wheels" U.S. Patent no. 138,707 (filed: 2 May 1873 ; issued: 6 May 1873).
    • Stith, Henry T. "Traction-wheel" U.S. Patent no. 224,741 (filed: 5 August 1879 ; issued: 17 February 1880).
    • Stith, Henry T. "Traction wheel" U.S. Patent no. 654,291 (filed: 26 December 1899; issued: 24 July 1900).
  21. ^ Biographical information about the American inventor Henry Thomas Stith (1839-1916) is available from the Kansas Historical Society.
  22. ^ "Invention of the Caterpillar Track: Frank Beamond and his Patents" (PDF). (PDF) from the original on 2015-07-21. Retrieved 2014-12-10.
  23. ^ "Lombard Log Hauler and Model T Snowmobile Show Route 175 Thornton, NH". from the original on 2011-08-14. Retrieved 2011-08-24.
  24. ^ GB 190416345, David Roberts, "Improvements in or connected with Road Locomotives and Vehicles.", published 1 Jun 1905 
  25. ^ The Devil's Chariots, John Glanfield
  26. ^ "About Caterpillar". Antique Caterpillar Machinery Owners Club. from the original on 2016-03-22. Retrieved 2016-11-07.
  27. ^ Haddock, Keith. Giant Earthmovers: An Illustrated History. MotorBooks International. pp. 17, 20, 21. ISBN 9781610605861. from the original on 2015-10-07. Retrieved 2015-08-16.
  28. ^ The Earthmover Encyclopedia, Page 28, Keith Haddock
  29. ^ "Cat's elevated sprocket that changed the dozer market". Equipment Journal. 2017-09-17.
  30. ^ R. F. Scott (1908). The Sledging Problem in the Antarctic, Men versus Motors
  31. ^ Roland Huntford (2003) Scott and Amundsen. Their Race to the South Pole. The Last Place on Earth. Abacus, London, p.224
  32. ^ riverbanksy (2011-08-21). 90 Degrees South. from the original on 2016-10-03. Retrieved 2016-10-23 – via YouTube.
  33. ^ Cherry-Garrard, Apsley (1922). The Worst Journey in the World. Vol. 2. London, England: Constable & Co. Ltd. p. 322.
  34. ^ Simkin, John. "Little Willie Tank". UK: Spartacus Educational. from the original on 2016-11-09. Retrieved 2016-11-08.
  35. ^ US patent 69987, James K Glen, "Improvement in Motive Power", issued 1867-10-22 
  36. ^ US patent 373887, William Fender, "Wheel With Endless Rail", issued 1887-11-29 
  37. ^ US patent 433488, Goldsbury Harden Pond, "Traction Engine", issued 1890-08-05 
  38. ^ Kane, Joseph Nathan, Famous First Facts, H. W. Wilson Company (1950), p. 47
  39. ^ US patent 351749, Charles Dinsmoor, "Vehicle", issued 1886-11-02  A design for a tracked vehicle.
  40. ^ Scientific American, December 18, 1886, Vol. LV, No. 25
  41. ^ . Lehman Brothers Collection. President and Fellows of Harvard College. 2010. Archived from the original on 2010-06-29. Retrieved 2010-11-06. In 1925 Holt and C.W. Best's company merged to form the Caterpillar Tractor Company.
  42. ^ "Austenitic Manganese Steels". from the original on 2012-03-08. Retrieved 2011-08-24.
  43. ^ Peter Chamberlain and Hilary Doyle, Encyclopedia of German Tanks of World War II, 1999
  44. ^ "Official website". Liebherr. from the original on 2006-10-14. Retrieved 2013-05-03.
  45. ^ "Kubota crawler tractor". Kubota.com. 2008-07-14. from the original on 2012-03-14. Retrieved 2013-05-03.
  46. ^ "Search results for Used Tracked tractors". Mascus.co.uk. from the original on 2013-06-02. Retrieved 2013-05-03.
  47. ^ Burner, Ken (1997). . Carnegie Mellon University. Archived from the original on 2012-06-22.
  48. ^ . Russia: Zavolzhsky Crawler Vehicle Plant. Archived from the original on 2013-11-27. Retrieved 2016-11-07.
  49. ^ "Main". Russia: Vityaz machine-building company. from the original on 2016-10-22. Retrieved 2016-11-07.

External links edit

  • Scale model of Hornsby Chain Tractor at 2005 Harrogate Model Engineering Show
  • Dedication to the only commercially-sold Hornsby caterpillar crawler

Video clips edit

continuous, track, tracked, treads, system, vehicle, propulsion, used, tracked, vehicles, running, continuous, band, treads, track, plates, driven, more, wheels, large, surface, area, tracks, distributes, weight, vehicle, better, than, steel, rubber, tyres, eq. 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 Continuous tracks on a bulldozerAn agricultural tractor with rubber tracks mitigating soil compactionA Russian tracked vehicle designed to operate on snow and swampsA British Army Challenger 1 tankModern continuous tracks can be made with soft belts of synthetic rubber reinforced with steel wires in 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 1 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 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 was first given a physical form by Hornsby amp 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 Contents 1 History 1 1 Heathcote s Steam Plough 1 2 Dreadnaught wheel by Boydell 1846 1 3 Endless Railway by John Fowler 1858 1 4 20th century efforts 1 5 First commercial success 1901 1 6 The stiff chain by Hornsby amp Sons 1904 1 7 Holt and the Caterpillar 1 8 Snow vehicles 1 9 Military application 2 Patent history 2 1 Linn 3 Engineering 3 1 Construction and operation 3 1 1 Overlapping road wheels 3 1 2 Drive train 3 1 3 Steering 3 2 Live and dead track 3 3 Rubber track pads 3 4 Rubber tracks 3 5 Advantages 3 6 Disadvantages 4 Gallery 5 Current manufacturers 6 In nature 7 See also 8 References 9 External links 9 1 Video clipsHistory editThe British polymath Sir George Cayley patented a continuous track which he called a universal railway in 1825 2 Polish mathematician and inventor Jozef Maria Hoene Wronski designed caterpillar vehicles in the 1830s to compete with the railways 3 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 was unable to build a working prototype and his patent was voided in 1839 Heathcote s Steam Plough edit nbsp Heathcote Steam Plough as demonstrated in 1837Patented in 1832 by John Heathcoat also Heathcote M P for Tiverton the Heathcote steam plough was demonstrated in 1837 and press coverage fortunately provided a wood cut of this unusual tracked vehicle 4 The continuous tracks were made of 215 cm 7 ft sections of wood bolted to continuous iron bands which were driven by the drums at each end A strong chassis provided the bearings for the drums and carried the steam engine fuel and winch The chassis was supported on numerous small wheels or rollers which ran upon the lower iron bands which thus form a perfectly portable and smooth road for the platform The drums were 275 or 305 cm 9 or 10 ft in diameter 790 cm 26 ft apart The tracks were each 215 cm 7 ft wide with a 215 cm 7 ft gap in between giving an overall width of 640 cm 21 ft The twin cylinder steam engine could be used either to drive the plough winch or to drive the vehicle along at a speed of up to 150 cm min 5 ft min Although the machine weighed 30 tons complete with 6 tons of fuel its ground pressure was only 869 kg m2 178 lb sq ft considerably less than a man The successful demonstration was carried out on Red Moss at Bolton le Moors on 20 April 1837 The steam plough was lost when it sank into a swamp by accident and was then abandoned as the inventor did not have the funds to continue development 5 6 Dreadnaught wheel by Boydell 1846 edit Main article Dreadnaught wheel 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 7 A number of horse drawn wagons carts and gun carriages were successfully deployed in 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 8 9 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 the lifting one or other of the driving wheels to facilitate turning A number of manufacturers including Richard Bach Richard Garrett amp Sons Charles Burrell amp Sons and Clayton amp 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 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 10 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 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 11 Between late 1856 and 1862 Burrell manufactured not less than a score of engines fitted with dreadnaught wheels In April 1858 the journal The Engineer gave a brief description of a Clayton amp 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 12 13 14 Steam tractors fitted with dreadnaught wheels had a number of shortcomings and notwithstanding the creations of the late 1850s were never used extensively 9 15 Endless Railway by John Fowler 1858 edit 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 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 16 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 17 rather than 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 18 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 a farmers exhibition in 1896 18 20th century efforts edit 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 19 In short whilst the development of the continuous track engaged the attention of a number of inventors in the 18th and 19th centuries 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 20 21 The last was for the application of the track to a prototype off road bicycle built for his son 1 The 1900 prototype 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 22 nbsp Lombard Steam Log Hauler Designed patented 1901 First commercial success 1901 edit A first effective continuous track was not only invented but really implemented by Alvin Orlando Lombard for the Lombard Steam Log Hauler citation needed He was granted 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 the tractor crawler citation needed At least one of Lombard s steam powered machines apparently remains in working order 23 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 the right to produce vehicles under his patent citation needed The stiff chain by Hornsby amp Sons 1904 edit At about the same time a British agricultural company Hornsby in Grantham developed a continuous track which was patented in 1905 24 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 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 citation needed The patent was purchased by Holt citation needed nbsp First Chain Tracked Tractor 1905 Richard Hornsby amp Sons nbsp Hornsby Chain Tracked Tractor 1907 enhanced Version Holt and the Caterpillar edit 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 the 70bhp No 2 machine the caterpillar 25 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 26 Caterpillar Tractor Company began in 1925 from 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 27 which had the advantage of keeping the main drive shaft away from ground shocks and dirt 28 and is still used in their larger dozers nbsp Two Holt 45 gasoline crawler tractors teamed up to pull a long wagon train in the Mojave Desert during construction of the Los Angeles Aqueduct in 1909 nbsp Caterpillar D9 High Drive The elevated drive sprocket offers advantages to large earth moving machines 29 Snow vehicles edit In 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 30 Snow vehicles did not yet exist however and so his engineer Reginald Skelton developed the idea of a caterpillar track for snow surfaces 31 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 32 Scott died during 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 33 nbsp Skid steer snow wing and snow pusher with tracked treadsIn 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 Military application edit Continuous track 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 34 During World War I Holt tractors were used by the British and Austro Hungarian armies to tow heavy artillery and stimulated 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 Patent history editA long line of patents disputes who was the originator of continuous tracks There were a number of designs that attempted to achieve a track laying mechanism although these designs do not generally resemble modern tracked vehicles 35 36 37 In 1877 Russian inventor Fyodor Abramovich Blinov created a horse drawn tracked vehicle called wagon moved on endless rails 18 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 a farmers exhibition in 1896 18 According to Scientific American Charles Dinsmoor of Warren Pennsylvania invented a vehicle on endless tracks patented as No 351 749 on November 2 1886 38 39 The article gives a detailed description of the endless tracks 40 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 the Northeastern United States and Canada citation needed 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 was later purchased by Holt in 1913 allowing Holt to claim to be the inventor of the crawler tractor 41 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 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 citation needed The Phoenix Centipeed typically had a fancier wood cab steering wheel tipped forward at a 45 degree angle and vertical instead of horizontal cylinders nbsp The draft of Blinov s steam powered continuous track tractor nbsp A working model of the original Hornsby amp Sons tracked tractorLinn edit Main article Linn tractor This section does not cite any sources Please help improve this section by adding citations to reliable sources Unsourced material may be challenged and removed May 2013 Learn how and when to remove this template message In the meantime a gasoline powered motor home was built by Lombard for Holman Harry Flannery Linn of Old Town Maine to pull the equipment wagon of his dog amp 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 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 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 citation needed Linn was a pioneer in snow removal before the practice was embraced in rural areas with 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 citation needed Engineering edit nbsp Diagram of tracked suspension 1 rear drive wheel rear wheel drive 2 track 3 return rollers 4 front drive wheel front wheel drive 5 road wheels 6 idler nbsp A sprocket wheel on a tankConstruction and operation edit Modern tracks are built from modular chain links which together compose 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 42 Track construction and assembly is dictated by the application Military vehicles use a track shoe that is integral to the structure of 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 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 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 a single bogie that includes the idler wheel and sometimes the sprocket nbsp Overlapped and interleaved road wheels of a German Tiger I heavy tank nbsp An Sd Kfz 11 s half track units showing the rims of its six Schachtellaufwerk overlapped interleaved roadwheel sets for each track unit per sideOverlapping road wheels edit 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 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 the load over the track 43 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 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 the track more evenly It also must have extended the life of the tracks and possibly of the wheels citation needed 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 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 citation needed but in peacetime vehicles must train several crews over a period of decades Drive train edit Transfer of power to the track is accomplished by 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 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 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 Steering edit Continuous track vehicles steer by applying more or less drive torque to one side of the vehicle than the other and this can be implemented in a variety of ways Main article Differential steering Live and dead track edit 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 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 Rubber track pads edit Tracks are often equipped with rubber pads to improve travel on paved surfaces more quickly smoothly and quietly While these pads slightly reduce 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 nbsp Small tracks on a roadworks machine Note the rubber pads to reduce wear on the carriageway nbsp Worn and new track pads on an M1 Abrams main battle tank nbsp Rubber tracks Case IH 8240 nbsp Tracked vehicles long distance hauling on semi trailers or railway carsRubber tracks edit 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 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 was invented and constructed by Adolphe Kegresse and patented in 1913 in historic context rubber tracks are often called Kegresse 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 Advantages edit Tracks are much less likely to get stuck in soft ground mud or snow since they distribute the weight of the vehicle over a larger contact area decreasing its ground pressure The seventy ton M1 Abrams tank has an average ground pressure of just over 15 psi 100 kPa Since tyre air pressure is approximately equal to average ground pressure a typical car will have an average ground pressure of 28 psi 190 kPa to 33 psi 230 kPa Tracked vehicles have better mobility over rough terrain than those with wheels They smooth out the bumps glide over small obstacles and are capable of crossing trenches or breaks in the terrain Riding in a fast tracked vehicle feels just like riding in a boat over heavy swells The larger contact area coupled with the cleats or grousers on the track shoes allows vastly superior traction that results in a much better ability to push or pull large loads where wheeled vehicles would dig in Bulldozers which are most often tracked use this attribute to rescue other vehicles such as wheel loaders which have become stuck in or sunk into the ground Tracks cannot be punctured or torn and are more resistant in military combat Should a track be broken it often can be repaired immediately using some special tools and spare parts without the need for special facilities which might be crucial in combat situations Disadvantages edit nbsp A JSDF Type 10 with a thrown trackThe disadvantages of tracks are lower top speed much greater mechanical complexity shorter life and 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 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 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 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 citation needed Gallery edit nbsp Komatsu CD 110R nbsp German World War II era SdKfz 251 military halftrack with overlapped interleaved wheels and slack track nbsp Experimental four track tank Obyekt 279 nbsp Soviet T 55 tank with slack track and rear drive sprocket nbsp U S M60 tank with rear drive sprocket and return rollers holding up the track nbsp Track of a Leclerc tank nbsp Experimental tracked landing gear on a B 36 PeacemakerCurrent manufacturers editThe pioneer manufacturers have been replaced mostly by large tractor companies such as AGCO Liebherr Group 44 John Deere Yanmar New Holland Kubota 45 Case Caterpillar Inc CLAAS 46 Also there are some crawler tractor companies specialising in niche markets Examples are Otter Mfg Co and Struck Corporation 47 with many wheeled vehicle conversion kits available from the American Mattracks firm of Minnesota since the mid 1990s Russian off road vehicles are built by companies such as ZZGT 48 and Vityaz 49 In nature editNavicula diatoms are known for their ability to creep about on each other and on hard surfaces such as microscope slides It is thought that around the outside of the navicula s shell is a girdle of protoplasm that can flow and thus act as a tank track See also editExcavator Half track Kegresse track Pedrail wheel Recreational products Screw propelled vehicle Snowcat Snowmobile Undercarriage AirollReferences edit a b The Tank Tread Was His Baby Popular Science June 63 1944 Archived from the original on 2017 03 13 Retrieved 2011 08 24 Sir George Cayley s patent universal railway Mechanics Magazine 5 127 225 227 1826 01 28 Archived from the original on 2017 03 13 Josef Maria Hoene de Wronski Archived from the original on 2009 08 11 Retrieved 2009 05 30 Heathcote s Steam Plough Chelmsford Chronicle US 29 December 1837 p 4 Classic Caterpillar Crawlers MotorBooks International 2001 ISBN 9781610605793 Brown Jonathan 2008 Steam on the Farm A History of Agricultural Steam Engines 1800 to 1950 Crowood Press ISBN 9781847970527 Burrell s traction engine with Boydell s endless railway Grace s Guide 1857 Archived from the original on 2013 10 02 Retrieved 2013 09 30 Lane Michael R 1994 The story of the St Nicholas Works A History of Charles Burrell and Sons London Unicorn Press ISBN 978 0906290071 a b Boydell Artillery Wheel PDF Archived PDF from the original on 2013 10 02 Retrieved 2013 09 30 Governments Experiments with Boydell s Traction Engine The Farmer s Magazine London 45 1 1856 06 30 Archived from the original on 2016 03 04 Tuxford s Boydell Traction Engine PDF Science amp Society Picture Library UK 1857 Archived PDF from the original on 2016 03 04 Retrieved 2014 02 04 Staff 23 April 1858 The iron coal and general trades of Birmingham Wolverhampton and other towns The Engineer 5 327 328 See p 328 left hand column Lane 1994 Clark Ronald H 1974 The Development of the English Traction Engine Cambridge UK Goose and Son ISBN 0900404027 Charles Burrell amp Sons Limited PDF University of Reading UK Archived PDF from the original on 2014 02 21 Retrieved 2013 09 30 Burrell Boydell Tractor PDF Archived PDF from the original on 2013 10 02 Retrieved 2013 09 30 Caley Georg 1825 Patent No 5260 A New Locomotive Apparatus PDF Archived PDF from the original on 2017 11 21 Retrieved 2013 09 30 a b c d Lozovoi D Lozova A Izobretatel traktora F Blinov The inventor of the tractor F Blinov Russia in Colours in Russian Archived from the original on 2011 07 27 Retrieved 2011 08 24 The Implement and Machinery Review 1901 01 02 Henry T Stith s patents for tracked wheels Stith Henry T Improvement in traction wheels U S Patent no 138 707 filed 2 May 1873 issued 6 May 1873 Stith Henry T Traction wheel U S Patent no 224 741 filed 5 August 1879 issued 17 February 1880 Stith Henry T Traction wheel U S Patent no 654 291 filed 26 December 1899 issued 24 July 1900 Biographical information about the American inventor Henry Thomas Stith 1839 1916 is available from the Kansas Historical Society Invention of the Caterpillar Track Frank Beamond and his Patents PDF Archived PDF from the original on 2015 07 21 Retrieved 2014 12 10 Lombard Log Hauler and Model T Snowmobile Show Route 175 Thornton NH Archived from the original on 2011 08 14 Retrieved 2011 08 24 GB 190416345 David Roberts Improvements in or connected with Road Locomotives and Vehicles published 1 Jun 1905 The Devil s Chariots John Glanfield About Caterpillar Antique Caterpillar Machinery Owners Club Archived from the original on 2016 03 22 Retrieved 2016 11 07 Haddock Keith Giant Earthmovers An Illustrated History MotorBooks International pp 17 20 21 ISBN 9781610605861 Archived from the original on 2015 10 07 Retrieved 2015 08 16 The Earthmover Encyclopedia Page 28 Keith Haddock Cat s elevated sprocket that changed the dozer market Equipment Journal 2017 09 17 R F Scott 1908 The Sledging Problem in the Antarctic Men versus Motors Roland Huntford 2003 Scott and Amundsen Their Race to the South Pole The Last Place on Earth Abacus London p 224 riverbanksy 2011 08 21 90 Degrees South Archived from the original on 2016 10 03 Retrieved 2016 10 23 via YouTube Cherry Garrard Apsley 1922 The Worst Journey in the World Vol 2 London England Constable amp Co Ltd p 322 Simkin John Little Willie Tank UK Spartacus Educational Archived from the original on 2016 11 09 Retrieved 2016 11 08 US patent 69987 James K Glen Improvement in Motive Power issued 1867 10 22 US patent 373887 William Fender Wheel With Endless Rail issued 1887 11 29 US patent 433488 Goldsbury Harden Pond Traction Engine issued 1890 08 05 Kane Joseph Nathan Famous First Facts H W Wilson Company 1950 p 47 US patent 351749 Charles Dinsmoor Vehicle issued 1886 11 02 A design for a tracked vehicle Scientific American December 18 1886 Vol LV No 25 Caterpillar Tractor Co List of Deals Lehman Brothers Collection President and Fellows of Harvard College 2010 Archived from the original on 2010 06 29 Retrieved 2010 11 06 In 1925 Holt and C W Best s company merged to form the Caterpillar Tractor Company Austenitic Manganese Steels Archived from the original on 2012 03 08 Retrieved 2011 08 24 Peter Chamberlain and Hilary Doyle Encyclopedia of German Tanks of World War II 1999 Official website Liebherr Archived from the original on 2006 10 14 Retrieved 2013 05 03 Kubota crawler tractor Kubota com 2008 07 14 Archived from the original on 2012 03 14 Retrieved 2013 05 03 Search results for Used Tracked tractors Mascus co uk Archived from the original on 2013 06 02 Retrieved 2013 05 03 Burner Ken 1997 The Small Tractor FAQ Tractor Resources Carnegie Mellon University Archived from the original on 2012 06 22 The Zavolzhsky Crawler Vehicle Plant Russia Zavolzhsky Crawler Vehicle Plant Archived from the original on 2013 11 27 Retrieved 2016 11 07 Main Russia Vityaz machine building company Archived from the original on 2016 10 22 Retrieved 2016 11 07 External links edit nbsp Look up continuous track in Wiktionary the free dictionary nbsp Wikimedia Commons has media related to Continuous tracks Scale model of Hornsby Chain Tractor at 2005 Harrogate Model Engineering Show Dedication to the only commercially sold Hornsby caterpillar crawler Hornsby Steam Chain Tractor websiteVideo clips edit Hornsby Chain Tractor Promotion Video 6 17 1908 British Film Institute Scale Model Hornsby Traktor Stapleford Steam Leicestershire 2008 1 3 Scale Hornsby Traktor Retrieved from https en wikipedia org w index php title Continuous track amp oldid 1183723038, wikipedia, wiki, book, books, library,

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