Three-point hitch
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The three-point hitch is a device used on farming tractors used for certain implements. These implements include those that are hooked on to the hitches of the tractor, as well as implements that are pulled and are connected to the hitches. The three points resemble either a triangle, or the letter A.
Components
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 stabalizers.
Three point hitches are composed of three movable arms. The two outer arms - the hitch lifting arms - are controlled by the hydraulic system, and provide lifting, lowered, and even tilting to the arms. The center arm - called the top link - is movable, but is 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, 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 setting are available.
There are several different hitch systems, called categories. Category Zero hitches are used with small farm or garden tractors. Category III hitches are found on the larger farm tractors, or those above 90hp.
History
Before the 1960's, each manufacturer used their own systems for hitching, or attaching their implements to their tractors. Farmers would have to purchase the same brand implements as their tractor to be able to correctly hook up the implement. A number of adapation kits - which were clumsy and often unsafe - had to be used if a farmer needed to use a different brand implement with the tractor.
Eventually, tractor and implement manufacturers agreed on one standard system to hitch tractors to implements. As patents on technology expires, the manufactures were able to refine the system, and nearly all the manufactures have adopted what would be come the three-point hitch system.
Links
- The inventor, Harry Ferguson (http://www.ulsterhistory.co.uk/harryferguson.htm)
- Three-point linkage model (http://www.ferguson-museum.co.uk/3_point.htm)