Coupling assembly

A coupling assembly operable between a first condition transmitting rotational force from a rotatable input member to a rotatable output member and a second condition retaining the output member against rotation, said coupling assembly comprising a stationary housing section, said stationary housing section including inner surface means for holding a body of liquid coolant, a clutch assembly at least partially enclosed by said stationary housing section and operable between an engaged condition in which said clutch assembly is effective to transmit rotational force conducted between the input member and the output member and a disengaged condition in which said clutch assembly is ineffective to transmit rotational force, said clutch assembly being at least partially disposed in said body of liquid coolant, a brake assembly at least partially enclosed by said stationary housing section and operable between an engaged condition in which said brake assembly is effective retain the output member against rotation relative to said stationary housing section and a disengaged condition in which said brake assembly is ineffective to retain the output member against rotation relative to said stationary housing section, said brake assembly being at least partially disposed in said body of liquid coolant, and actuator means at least partially enclosed by said stationary housing section for effecting operation of said clutch assembly between the engaged and disengaged conditions and for effecting operation of said brake assembly between the engaged and disengaged conditions, said actuator assembly being at least partially disposed in said body of liquid coolant, and cooling fluid passage means extending around said stationary housing section for conducting a flow of cooling fluid which is maintained separate from the body of liquid coolant disposed in said housing, said stationary housing section including outer side surface means which is exposed to the flow of cooling fluid to facilitate heat transfer from the body of liquid coolant disposed in said housing to the flow of cooling fluid even though the flow of cooling fluid is maintained separate from the body of liquid coolant in said housing.