cavity 20 is facilitated by the openings 44 in the second plates 14 the fluid then passes between the first plates 12 and the second plates 14 to reach the fluid outlet 64 after leaving the plate cavity 20 the fluid enters the heat exchanger 68 to cool the fluid and then enters the pump 66 which forces the fluid back into the stationary housing inlet 58 when the voltage is applied to the plates 12 and 14 the electro rheological fluid between the facing surfaces 16 and 18 increases in stiffness flow of fluid between the facing surfaces 16 and 18 from the inside diameter 56 of the first plates 12 to the outside diameter 57 of the second plates 14 is greatly reduced this restriction results in an increase in pressure in the plate cavity 20 inside of the inside diameter 56 of the first plate and in the piston cavity 60 there is no restriction of fluid flow out of the piston cavity 60 so the pressure within the piston 60 cavity but outside of outside diameter 57 of the second plates 14 is relatively unaffected and remains low the increase in pressure on the apply side 72 of.