Patent ID: 8662274

Claim:
A rotational coupling device, comprising: an output hub disposed about an axis of rotation; an input ring disposed about said output hub and said axis; a first friction disc coupled to said output hub for rotation therewith and axially movable relative thereto; a second friction disc coupled to said input hub for rotation therewith and axially movable relative thereto; an actuator assembly, comprising: a field shell fixed against rotation, said field shell defining axially extending, radially spaced inner and outer field shell poles configured to receive a conductor therebetween; a pole structure defining axially extending, radially spaced inner and outer actuator poles and an end wall extending radially therebetween, said inner and outer actuator poles radially aligned with corresponding ones of said inner and outer field shell poles; an armature coupled to said input ring for rotation therewith and axially movable relative to said input ring, said armature axially aligned with said end wall of said pole structure; a first actuator disc disposed about said output hub and coupled to said pole structure, said first actuator disc disposed radially between said pole structure and said output hub; a second actuator disc disposed about said output hub and axially spaced from said first actuator disc, said second actuator disc disposed radially between said pole structure and said output hub, at least one of said first and second actuator discs defining a plurality of cam surfaces; and, a plurality of balls disposed between said first and second actuator discs, each ball of said plurality of balls in engagement with a corresponding cam surface of said plurality of cam surfaces; wherein energization of said conductor causes engagement of said armature with said pole structure and transfer of torque to said pole structure and said first actuator disc resulting in movement of said plurality of balls along said plurality of cam surfaces and axial movement of said second actuator disc towards said first and second friction discs.