Torque transfer apparatus

A hydraulic power transfer apparatus comprising a power cylinder, a power piston mounted for reciprocation in the power cylinder, the power piston having a piston rod for connection to a power take off, an auxiliary piston mounted in a head end of the power cylinder in opposition to the power piston, the auxiliary piston having an exposed cam follower, a driven cam associated with the cam follower for moving the auxiliary piston in the power cylinder toward the power piston, a pump cylinder, a pump piston reciprocally mounted in the pump cylinder, drive means for providing reciprocation of the pump piston in the pump cylinder, a hydraulic fluid supply line extending from the pump cylinder to the power cylinder for supplying fluid under pressure from the pump cylinder to the power cylinder, said supply line communicating with an inlet port in the side of the power cylinder, and a delivery line extending from an outlet port in the side of the power cylinder to the pump cylinder for the return of hydraulic fluid from the power cylinder to the pump cylinder, wherein movements of the pump piston and cam are coordinated to provide reciprocation of the power piston in the power cylinder with the cam and auxiliary piston being effective to provide movement of the power piston away from the head end of the power cylinder until the power piston uncovers said inlet port, and the power piston on return strokes toward the head end of the power cylinder being effective to move the auxiliary piston and cam follower outwardly toward the cam whereby the follower reengages the cam after the power piston covers said outlet port.