A power transmission device includes a rotary input member receiving drive torque from a source of torque, a rotary output member for providing drive torque to an output device and a torque transfer mechanism for transferring drive torque between the input member and the output member. The torque transfer mechanism includes a friction clutch assembly operably disposed between the input member and the output member and a hydraulic clutch actuation system operable for applying a clutch engagement force to the friction clutch assembly. The hydraulic clutch actuation system includes an electric motor drivingly coupled to the hydraulic actuator. The hydraulic actuator includes a first piston biasedly engaged by a spring, slidably positioned within a housing and operable to supply pressurized fluid to a second piston. Supply of pressurized fluid to the second piston provides the clutch engagement force.