Three-point hitch

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. The three points resemble either a triangle, or the letter A. Three-point attachment is the simplest and the only statically determinate way of joining two bodies in engineering.

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 (1,100 kg), the 9N could plow more than 12 acres (5 hectares) in a normal day pulling two 14-inch (360 mm) plows, outperforming the tractive performance of the heavier and more expensive Farmall F-30 model. The hitch's utility and simplicity have since made it an industry standard.

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.

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