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» Economics » Tool » Topics begins with T » Three point hydraulics

Page modified: Wednesday, July 13, 2011 18:04:26

Under three point hydraulics (English: three POINT hitch) one understands a hydraulic rockshaft, which is attached usually at the back of a tractor and which can be moved over hydraulics up and off.

At the three point attachment attachments so mentioned (implements) can be attached and pulled, be propelled either over the power-takeoff of the tractor or over hydraulic additional connections.

The three point attachments are today standardized; depending upon tractor size these are divided into the categories 1 to 3.


"Three point" is called the system, because the implements are fastened to three points to the tractor. With the two lower lift arms hydraulics is raised; the upper attachment arm (center link) serves as hinge and between of the attachment and the tractor is fastened.

Here a waagereche wave with two levers at its end, arranged deeply at the tail of the tractor, is made adjustable by a Hubhydraulik in the vertical lift. The lever ends represent the lower two points of the three-point hitch. The third point is been more highly, because of approx. spindle of equal length and however an adjustable over the trailer coupling and under the seat carrier you realizes a coupling over a lever of same length as the lower. Thus by three-lever parallelogram lifting and lowering the cultivated aggregate are permitted to steer via hydraulics, without changing substantially the inclination of the cultivation aggregate. Usually for it as upper levers an lengthen-adjustable spindle one uses, so that by the tractor seat from simply the inclination can be adjusted.

This system was invented 1953 by the US-American tractor farmer Ferguson.

This system can limit the operating depth of the plow in the depth. By the cultivation the plow with the tractor becomes a unit, which becomes developing introduction forces of the plow to the drive axle transfers, which increases the tractive power. Ferguson invented the center link regulation. By the arising resistance, which is exercised during plowing on the plow bottoms, forces are called, transferred to the upper linkage, center link. These forces are now used doubly:

  1. As rule strength, more thrust force = more tensile strength = the lifting gear raises the plow or in reverse, less thrust force = the lifting gear lowers the plow more deeply.
  2. The thrust force prevents the raising of the front axle.

In the further one now the plow without trouble can be lifted and lowered.


The inventor of the three-point hitch is the Irish Harry Ferguson. In the year 1928 he built the "Black Tractor", a black-painted tractor with transmission parts of David Brown and a Herkulesmotor, which came from the USA. It noticed soon that black was an unfavorable color, and changed thereupon on grey. The "Black Tractor" stands today in the Londoner Science museum.

It united in the following years with the English tractor manufacturer David Brown. 1936 appeared the first series tractor with the Ferguson system, the Ferguson Brown type A.

It already united to 1938 with the American automobile and tractor manufacturer Henry Ford. 1938 appeared also the first Ford tractor with the Dreipunktkupplung, the type 9N. Ferguson separated from Ford according to a longer controversy in the year 1947. Thereupon it built tractors from 1947 to 1953.

1953 it sold its factory to the Canadian agricultural machinery manufacturer Massey Harris. From this Massey Ferguson developed.

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