Viscous actuated ball ramp clutch having through shaft capability

A differential device including an input adapted to receive input torque, an output adapted to provide driving torque to an output device, and a clutch pack including at least a first friction disc fixed to rotate with said input, and at least a second friction disc fixed to rotate with said output;

• means operable to move said friction discs between a disengaged position and an engaged position, said means comprising a cam ramp actuator including first and second ramp plates, and a plurality of cam members, each operably disposed between said first and second ramp plates, and in engagement with first and second ramp surfaces, respectively;
• said second ramp plate being disposed axially adjacent said friction discs and being operable to move said friction discs toward said engaged position;
• said means operable to move said friction discs further comprising a viscous coupling including an input coupling member fixed to rotate with said input, and an output coupling member;
• characterized by:
• (a) one of said input and said output defining a plurality of N elongated cut-out portions on the outer periphery thereof;
• (b) one of said first friction disc and said second friction disc defining a plurality N of cut-out portions cooperating with said elongated cut-out portions defined by said one of said input and said output to define a plurality N of openings;
• (c) a plurality N of elongated members, each member disposed in one of said openings, and operable to transmit torque between said one of said first friction disc and said second friction disc and said one of said input and said output;
• and
• (d) said openings having an axial length L1, and each of said elongated members having an axial length L2, less than L1, the difference therebetween being selected such that wear within said clutch pack will permit L1 to decrease to L2, but will prevent said cam ramp actuator from moving to an over-center condition.