The three-point hitch (British English: three-point linkage) is a widely used type of hitch for attaching ploughs and other implements to an agricultural or industrial tractor.[1][2] The three points resemble either a triangle, or the letter A. In engineering terms, three-point attachment is the simplest and the only statically determinate way of rigidly joining two bodies.
A three-point hitch attaches the implement to the tractor so that the orientation of the implement is fixed with respect to the tractor and the arm position of the hitch. The tractor carries some or all of the weight of the implement. The other main mechanism for attaching a load is through a drawbar, a single point, pivoting attachment where the implement or trailer is not in a fixed position with respect to the tractor.
The primary benefit of the three-point hitch system is to transfer the weight and resistance of an implement to the drive wheels of the tractor. This gives the tractor more usable traction than it would otherwise have, given the same power, weight, and fuel consumption. For example, when the Ford 9N introduced Harry Ferguson's three-point hitch design to American production-model tractors in 1939, it was a light and affordable tractor competing principally with row-crop tractors such as Farmalls that did not yet have three-point hitches. At 2,500 pounds (1.1t), the 9N could plow more than 12 acres (4.9 hectares) in a normal day pulling two 14-inch (360mm) plows,[3] outperforming the tractive performance of the heavier and more expensive Farmall F-30 model.[3] The hitch's utility and simplicity have since made it an industry standard.
Components
Three-point linkage on a Ferguson 35 tractor. The tractor and linkage are painted gold. The grey bars are a separate implement (a towing ball hitch) attached to the linkage.
The three-point hitch is made up of several components working together. These include the tractor's hydraulic system, attaching points, the lifting arms, and stabilizers.
Three-point hitches are composed of three movable arms. The two lower arms—the hitch lifting arms—are controlled by the hydraulic system, and provide lifting, lowering, and even tilting to the arms. The upper center arm—called the top link—is movable, but is usually not powered by the tractor's hydraulic system. Each arm has an attachment device to connect implements to the hitch.
Each hitch has attachment holes for attaching implements, and the implement has posts that fit through the holes. The implement is secured by placing a pin on the ends of the posts.
The hitch lifting arms are powered by the tractor's own hydraulic system. The hydraulic system is controlled by the operator, and usually a variety of settings are available. A draft control mechanism is often present in modern three-point hitch systems. The draft of the implement, the amount of force it is taking to pull the implement, is sensed on the top link and the hydraulic system automatically raises the arms slightly when the draft increases and lowers the arms when the draft decreases.
Size categories
Adjustable three-point ball on lift arm. Ball may be rotated to fit either Category I or Category II implementsRear three-point hitch of a Case IH tractor with implement attached by the drawbar
There are five different hitch sizes, called categories. The higher category hitches have sturdier lift arms and larger connector pins.[2]
There are also variants to the above categories denoted by N (narrow). These utilize the pin sizes of the listed category, but the width of a category one step lower. The N variations are common in "quick hitches" and allow larger tractors to easily hook onto smaller utility implements.
History
Before the 1940s, most hitching of farm implements to tractors was done simply with a drawbar, on the same principle as a modern tow hitch. The drawbar was a flat bar with holes in it, and the implements were trailers, with tongues that attached to the drawbar with a pin through a hole. The main reason why this was the default hitching idea is that it was the natural follow-on from the days of horse-drawn implements, which were towed as trailers by the horse or team (and often had an operator's seat). In fact, for decades during the mechanisation of agriculture in Europe and North America, as tractors gradually replaced horses in increasing degrees, existing implements from the horse era were often what the tractor pulled. Towing with a drawbar is a good, practical system for many purposes, and it has continued to be used even up to today, but the three-point hitch outperforms it in several ways (described below).
Harry Ferguson patented the three-point linkage for agricultural tractors in Britain in 1926. He had long been a champion of the importance of rigid attachment of the plough to the tractor. The idea did not originate with him, but he led its popularization over many years of development, explaining, and selling. During the decade of 1916 to 1926 he developed his ideas through various iterations, duplex and triplex, mechanical and hydraulic, to arrive at the patented form. During the next decade, he continued explaining and selling his hitches and implements and even produced his own model of tractor in cooperation with David Brown Ltd. via the Ferguson-Brown Company. The particular geometry of the linkage that attached the plough to the tractor enabled forces generated by the plough to be applied to the rear wheels of the tractor. This redirected the plough's resistance into downward force on the drive wheels, which enabled Ferguson's tractor to be much lighter and more manoeuvrable than earlier models of farm tractor with equivalent tractive force and traction. As a result his tractor could operate on soft ground and caused less compacting damage to the soil in comparison with other tractors of the time, and it could produce given amounts of work with less time and fuel. The hydraulically operated and controlled three-point hitch used the draft of the mounted tool to moderate the depth of the tool and therefore the load on the tractor (automatic depth control or draft control). In addition, the three-point hitch would prevent the tractor from flipping backwards on the drive wheels if the implement being dragged were to hit a rock or other immovable obstruction. Ferguson and his colleagues developed several innovations to this device (e.g., the hydraulic lift and depth control) which made the system workable, effective, and desirable. In 1938, after almost two decades of trying to sell Henry Ford on using Ferguson's system on tractors mass-produced by Ford, Ferguson finally convinced Ford. The American mass-market debut was via the Ford-Ferguson 9N in 1939.
The Ferguson system, as it was called, was not just an improved hitch but rather the hitch plus an entire line of implements purpose-built to make full use of its advantages. During the 1940s, it was so advantageous and popular that other manufacturers were compelled to come up with competing hitch improvements that could also be pitched as proprietary "systems" with at least some of the features of the Ferguson system (such as quick, easy hitching and unhitching, implement raising and lowering controlled from the tractor seat, and treating the tractor and implement as a unit rather than an articulated pair). Thus, International Harvester developed its Fast Hitch and began to advertise the notion of "farming with the Farmall system" and Allis-Chalmers introduced its Snap-Coupler which allowed the operator to hook and unhook implements without leaving the operator's seat. Likewise, JI Case developed its Eagle Hitch, and similar path was followed at John Deere. Some of these systems, with one-point or two-point hitching, were not well suited to lifting heavy implements. They also presented the problem of incompatibility between brands of tractors and implements, applying pressure toward vendor lock-in that many farmers resented. During the 1950s and 1960s, farmers often would have to purchase the same brand implements as their tractor to be able to hook up the implement correctly or to best effect. If a farmer needed to use a different brand of implement, an adaptation kit—which were typically clumsy, ill-fitting, or unsafe—was sometimes needed. The pressure toward vendor lock-in was a two-edged blade for the salespeople. It was an advantage in cases where it encouraged the sale of implements (e.g., a farmer decided to purchase not just a tractor but also new implements to replace his old ones, betting on increased productivity to make it worth the cost), but it was a disadvantage to the extent that farmers did not see the value in a special new hitch if they could not afford also to buy new implements to make full use of it or felt uneasy about buying new implements when they already had existing implements that were still usable. Ferguson often faced the latter problem in the UK and Ireland in the 1920s and 1930s, and it also applied to the competitors' proprietary hitches of the 1940s and 1950s.
In the 1960s, as patents on the technology expired, tractor and implement manufacturers agreed on the three-point hitch as the one standard, interchangeable, full-featured system to hitch implements to tractors. With the advent of nonproprietary status, the manufacturers were able to refine the system and create useful modifications. Now, nearly all manufacturers have adopted some standardised[1] form of the modern three-point hitch system; many companies also offer safe adaptation kits for converting the non-standard hitch systems to the three-point hitch system.
A tractor is an engineering vehicle specifically designed to deliver a high tractive effort at slow speeds, for the purposes of hauling a trailer or machinery such as that used in agriculture, mining or construction. Most commonly, the term is used to describe a farm vehicle that provides the power and traction to mechanize agricultural tasks, especially tillage, and now many more. Agricultural implements may be towed behind or mounted on the tractor, and the tractor may also provide a source of power if the implement is mechanised.
A power take-off or power takeoff (PTO) is one of several methods for taking power from a power source, such as a running engine, and transmitting it to an application such as an attached implement or separate machine.
Fordson was a brand name of tractors and trucks. It was used on a range of mass-produced general-purpose tractors manufactured by Henry Ford & Son Inc from 1917 to 1920, by Ford Motor Company (U.S.) and Ford Motor Company Ltd (U.K.) from 1920 to 1928, and by Ford Motor Company Ltd (U.K.) alone from 1929 to 1964. The latter also later built trucks and vans under the Fordson brand.
The Ferguson-Brown Company was a British agricultural machinery manufacturing company formed by Harry Ferguson in partnership with David Brown.
Henry George Ferguson was a British mechanic and inventor who is noted for his role in the development of the modern agricultural tractor and its three point linkage system, for being the first person in Ireland to build and fly his own aeroplane, and for developing the first four-wheel drive Formula One car, the Ferguson P99.
The Ferguson TE20 is an agricultural tractor designed by Harry Ferguson. By far his most successful design, it was manufactured from 1946 until 1956, and was commonly known as the Little Grey Fergie. It marked a major advance in tractor design, distinguished by light weight, small size, manoeuvrability and versatility. The TE20 popularised Harry Ferguson's invention of the hydraulic three-point hitch system around the world, and the system quickly became an international standard for tractors of all makes and sizes that has remained to this day. The tractor played a large part in introducing widespread mechanised agriculture. In many parts of the world the TE20 was the first tractor to be affordable to the average farmer and was small and light enough to replace the draft horse and manual labour. Many TE20s remain in regular use in farming and other work and the model is also a popular collector's item for enthusiasts today.
A cultivator is a piece of agricultural equipment used for secondary tillage. One sense of the name refers to frames with teeth that pierce the soil as they are dragged through it linearly. Another sense of the name also refers to machines that use the rotary motion of disks or teeth to accomplish a similar result, such as a rotary tiller.
Farmall was a model name and later a brand name for tractors manufactured by International Harvester (IH), an American truck, tractor, and construction equipment company. The Farmall name was usually presented as McCormick-Deering Farmall and later McCormick Farmall in the evolving brand architecture of IH.
The Ford N-series tractors were a line of farm tractors produced by Ford between 1939 and 1952, spanning the 9N, 2N, and 8N models.
A drawbar is a solid coupling between a hauling vehicle and its hauled load. Drawbars are in common use with rail transport; road trailers, both large and small, industrial and recreational; and agricultural equipment.
The Farmall H is a medium-sized two-plow row crop tractor produced by International Harvester under the Farmall brand from 1939 to 1954. It was the most widely produced of International Harvester's "letter series", with approximately 390,000 produced over the 14-year run. It succeeded the Farmall F-20. The H was incrementally updated with new model numbers as the Super H, 300, and 350, but remained essentially the same machine. The original H used an International Harvester C152 4-cylinder in-line engine. Production of all versions lasted until 1963.
The Farmall M is a large three-plow row crop tractor produced by International Harvester under the Farmall brand from 1939 to 1953. It was of International Harvester's "letter series". It succeeded the Farmall F-30. The M was incrementally updated with new model numbers as the MD Super M, Super MD Super M-TA, but remained essentially the same machine. The original M used an International Harvester C248 4-cylinder in-line engine. Production of all versions lasted until 1954, when it was replaced by the Farmall 400 which was essentially the same machine with updated sheet metal.
The Farmall A is a small one-plow row crop tractor produced by International Harvester under the Farmall brand from 1939 to 1947. The tractor was popular for its set of innovative features in a small, affordable implement. It succeeded the Farmall F-14. The A was incrementally updated with new model numbers as the Super A, 100, 130 and 140, but remained essentially the same machine. Like the smaller Farmall Cub, the Farmall A features a distinctive offset engine, displaced to the left over wide-set front wheels, to allow vision straight ahead. An International Harvester C113 4-cylinder in-line engine was used for early models, increased to an IH C123 with the A-1. The most significant change was the introduction of hydraulics with the Super A. The series was produced until 1973.
The Farmall F-12 is a small two-plow row crop tractor produced by International Harvester under the Farmall brand from 1932 to 1938, with approximately 123,000 produced. An improved model, the two-plow F-14, was produced beginning in 1938 and ending in 1939, when the Farmall letter series tractors were introduced.
The Farmall 04 series tractors are a family of row-crop tractors with four-cylinder engines, continuing the tradition of four-cylinder engines in Farmall and parent company International Harvester for general-purpose and row-crop tractors. In the early 1960s demand for more power led to the 06 series with six-cylinder engines. Four-cylinder engines were reserved for tractors equivalent to the Farmall H and smaller.
The Farmall 06 series tractors are a family of row-crop tractors with six-cylinder engines, providing greater horsepower than the parallel product line of four-cylinder Farmall 04 series tractors. Until the late 1950s, Farmall and parent company International Harvester tractors used four-cylinder engines for general-purpose and row-crop tractors. Demands for higher performance and greater horsepower led to broader use of six-cylinder engines, with the bulk of International's production moving to the larger engines. The Farmall 806 and 706 were introduced in 1963, with production running to 1967. The Farmall 1206 was introduced in 1965 as the most powerful tractor of its time, using a turbocharged diesel engine. Production of the 1206 also ran until 1967. The 06 series sold well and was regarded as extremely successful.
The John Deere Model GP tractor was a two-plow, and later a three-plow row-crop tractor produced by John Deere from 1928 to 1935. Initially called the John Deere Model C, the name was changed to GP as a result of difficulties in distinguishing between the Model C and Model D over the telephones of the time. It was intended as a response to the Farmall Regular line of general-purpose tractors produced under the Farmall brand by International Harvester..
The Oliver 70 series of row-crop tractors was a series of large agricultural tractors produced from 1935 to 1967 by the Oliver Farm Equipment Company. Oliver tractors were known for their powerful engines compared to competitors, and their attention to styling. The Oliver Hart-Parr 70 marked the beginning of a strikingly-styled series of tractors that were produced under both the Oliver and the Cockshutt names. Oliver's emphasis on styling strongly influenced offerings by competing brands such as Farmall and John Deere.
The Oliver 60 series of row-crop tractors was a product line of agricultural tractors produced from 1940 to 1964 by the Oliver Farm Equipment Company. The 60 series was a four-cylinder follow-on to the six-cylinder Oliver 70. As the 70 was outsold by the less-expensive Farmall A, Allis-Chalmers Model B and John Deere Model B, Oliver introduced the 60 to compete.
The Oliver Super 55 series of utility tractors was developed and produced from 1954 to 1958 by the Oliver Farm Equipment Company to complement the Oliver line of heavy row-crop and standard agricultural tracts. Like row-crop tractors, the wheel track width could be adjusted to conform to crop row spacing, but the front wheels were only offered with a wide track. No narrow front wheel options were offered, making the tractor more stable with front-end loaders.
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