Patent ID: 7759811

Claim:
A hydraulic system for driving an auxiliary power source, located aboard a motor vehicle having a primary power source, at a substantially constant speed despite fluctuations in rotational speed of the primary power source, the system comprising: a variable displacement hydraulic pump drivably connectable to the primary power source, the hydraulic pump having an inlet for receiving fluid, an outlet for discharging fluid under pressure and a pump displacement input; a hydraulic motor drivably connectable to an auxiliary power source, the hydraulic motor having an inlet for receiving fluid under pressure and an outlet for discharging fluid; a fluid circuit including a supply conduit for conducting fluid discharged by the pump to the motor, a return conduit for returning fluid discharged by the motor to the pump; a pump displacement control cooperating with the pump displacement input in order to vary the displacement of the pump; and a control circuit in communication with the pump displacement control for controlling the pump output so that a desired hydraulic motor and associated auxiliary power source speed can be maintained.