Patent ID: 6997299

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; 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 a primary fluid circuit and a separate secondary fluid circuit interconnected by a pressure intensifier, said second fluid circuit including a piston selectively engageable with said friction clutch assembly; and a controller to establish the value of an electric control signal based on a rotary speed difference between said input member and said output member, and wherein said control signal is operable to vary the pressure supplied to said piston chamber for causing torque to be transferred by said friction clutch assembly.