3 Point Hitch Technical Page from Agri Supply®

The 3 Point Hitch System is the standard used hitch system on most tractors today. Refer to Drawing A below. The purpose of the system is for the attachment of your agricultural implements, as well as the adjustment of your implements. As shown in Drawing B below, the top link and the two lower lift arms are the primary make-up of the 3 point hitch system. If you, the tractor operator, need to lower, raise or tilt your agricultural implement, a simple adjustment of any one, or all three of the primary pieces is all that it takes.

Definitions
CATEGORIES 0,1,2,3 & 4 = System used for classifying tractors by their drawbar horsepower.