Patent ID: 7182194

Claim:
A power transmission device comprising: a rotary input member adapted to receive drive torque from a source of torque; a rotary output member adapted to provide drive torque to an output device; and a torque transfer mechanism operable for transferring drive torque from said input member to said output member, said torque transfer mechanism including a friction clutch assembly operably disposed between said input member and said output member and a hydraulic clutch actuation system operable for applying a clutch engagement force to said friction clutch assembly, said hydraulic clutch actuation system including an electric motor drivingly coupled to a hydraulic actuator, said hydraulic actuator including a first piston biasedly engaged by a spring, said first piston being slidably positioned within a housing and operable to supply pressurized fluid to a second piston, said spring being sized to store a predetermined quantity of energy such that supply of said pressurized fluid to said second piston provides said clutch engagement force.