A rotational coupling device, comprising: a hub configured for coupling to a shaft for rotation with said shaft about an axis of rotation; a rotor supported on said hub and configured for rotation relative to said hub about said axis of rotation, said rotor including a first member defining a radially extending wall having a first rotor coupling surface and an axially extending, radially inner rotor pole; and, a second member coupled to said first member for rotation therewith, but axially movable relative to said first member, said second member defining an axially extending, radially outer rotor pole, a second rotor coupling surface and a first braking surface; an armature supported on said hub for rotation therewith and disposed on a first side of said radially extending wall of said rotor; a field shell disposed about said hub on a second side of said radially extending wall of said rotor opposite from said armature, said field shell housing a conductor therein and defining radially spaced inner and outer field shell poles (208, 210) aligned with said inner and outer rotor poles (130, 164), respectively, energization of said conductor establishing an electromagnetic circuit among said field shell, said rotor and said armature to urge said armature in a first axial direction towards said radially extending wall of said rotor and couple said rotor to said hub for rotation therewith; and, a first brake plate defining a second braking surface aligned with said first braking surface of said second member of said rotor wherein said second member of said rotor is configured such that, upon energization of said conductor, said second member of said rotor is urged towards said first member of said rotor and said second rotor coupling surface is urged into engagement with said first rotor coupling surface and, upon deenergization of said conductor, said second member of said rotor is urged towards said first brake plate, said first braking surface is urged into engagement with said second braking surface and said second rotor coupling surface is urged to disengage from said first rotor coupling surface to create a fluid flow opening between said first and second members (100, 104) of said rotor. a hub configured for coupling to a shaft for rotation with said shaft about an axis of rotation; a rotor supported on said hub and configured for rotation relative to said hub about said axis of rotation, said rotor including a first member defining a radially extending wall having a first rotor coupling surface and an axially extending, radially inner rotor pole; and, a second member coupled to said first member for rotation therewith, but axially movable relative to said first member, said second member defining an axially extending, radially outer rotor pole, a second rotor coupling surface and a first braking surface; an armature supported on said hub for rotation therewith and disposed on a first side of said radially extending wall of said rotor; a field shell disposed about said hub on a second side of said radially extending wall of said rotor opposite from said armature, said field shell housing a conductor therein and defining radially spaced inner and outer field shell poles (208, 210) aligned with said inner and outer rotor poles (130, 164), respectively, energization of said conductor establishing an electromagnetic circuit among said field shell, said rotor and said armature to urge said armature in a first axial direction towards said radially extending wall of said rotor and couple said rotor to said hub for rotation therewith; and, a first brake plate defining a second braking surface aligned with said first braking surface of said second member of said rotor wherein said second member of said rotor is configured such that, upon energization of said conductor, said second member of said rotor is urged towards said first member of said rotor and said second rotor coupling surface is urged into engagement with said first rotor coupling surface and, upon deenergization of said conductor, said second member of said rotor is urged towards said first brake plate, said first braking surface is urged into engagement with said second braking surface and said second rotor coupling surface is urged to disengage from said first rotor coupling surface to create a fluid flow opening between said first and second members (100, 104) of said rotor.