Patent ID: 7278943

Claim:
A power transmission device comprising: a first rotary member; a second rotary member; a torque transfer mechanism operable for transferring drive torque between said first and second members, said torque transfer mechanism having a transfer clutch disposed between said first and second rotary members, a rotary operator and a thrust mechanism for applying a clutch engagement force to said transfer clutch, said transfer clutch including a hub driven by said first rotary member, a drum driven by said second rotary member and a clutch pack operably disposed between said hub and said drum, said rotary operator including a first component rotatably driven by said hub and a second component aligned with said first component so as to define an actuation chamber therebetween, said second component is adapted to rotate relative to said first component in response to fluid pressure in said actuation chamber, said thrust mechanism is operable to apply said clutch engagement force to said clutch pack in response to rotation of said second component relative to said first component; and a hydraulic control system for regulating the fluid pressure supplied to said actuation chamber.