Patent ID: 7059460

Claim:
A hydraulic coupling system, comprising a pump; a clutch assembly including an actuator and a multi-disk clutch pack coupled to the actuator, the pump pressuring a fluid in the actuator to engage the clutch pack and pumping the fluid through the clutch pack to cool the clutch pack; a pressure control valve communicating wit a reservoir, the actuator and the clutch pack for maintaining the fluid pumped to the actuator at a higher pressure than the pressure of the fluid pumped through the clutch pack to cool the clutch; a two-way valve which provides a preload pressure to the system when the pump is not operating and the clutch pack is disengaged; and a controller which transmits pulse-width modulated control signals to the pump to control the operation of the pump and pulse-width modulated control signals to the valve to control the operation of the valve.