Harry Ferguson patented the three-point 'linkage' for agricultural tractors in Britain in 1926. His credit does not lie in invention of the device, but in realisation of the importance of rigid attachment of the plough to the tractor. He is also attributed with several innovations to this device (e.g. hydraulic lift) which made this system workable, effective, and desirable to the point of using it on mass marketed tractors (e.g. the Ford-Ferguson 9N). The hydraulically operated and controlled three point hitch utilized the draft of the mounted tool to moderate the depth of the tool and therefore the load on the tractor.
Before the 1940s, each manufacturer used their own systems for hitching, or attaching their implements to their tractors. Commonplace was the two-point hitch system which could not effectively be used for lifting many implements. At this time, farmers would have to purchase the same brand implements as their tractor to be able to correctly hook up the implement. If a farmer needed to use a different brand implement with the tractor an adaptation kit - which were typically clumsy, ill-fitting, or unsafe - had to be installed.
In the 1960s, tractor and implement manufacturers would eventually agree on the three-point hitch as the one standard system to hitch implements to tractors. As patents on technology expired, the manufacturers were able to refine the system and create useful modifications. Now, nearly all manufacturers have adopted some standardised
http://en.wikipedia.org/wiki/Three-point_hitch#cite_note-0 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.
