Controlling tractor hydraulic lift arms - ensures arms of three point linkage move parallel to one another

摘要

A control apparatus is provided for controlling the movement of the arms of a conventional three point linkage disposed at the rear of a tractor for supporting auxiliary equipment and moving it between operative and inoperative positions. Two hydraulic cylinders contain double acting pistons and are pivotally connected to a tractor on a common horizontal axis via the eyes provided at one end of each cylinder. A respective rod connected to each piston form the first pair of linkages and a third similar linkage is disposed below the first two. A comprehensive metering and compensating hydraulic circuit enables the movement of the three linkages to be coordinated.