Patent ID: 8579752

Claim:
A hydraulic coupling for use in a vehicle drivetrain including a pair of rotary members, said hydraulic coupling comprising: a casing operatively supporting the pair of rotary members; a coupling mechanism supported in said casing and operable to selectively couple the pair of rotary members together; a piston moveably supported in said casing between a first position and a second position defining an expandable chamber; a pump operable to provide a source of pressurized fluid in response to differential movement between the pair of rotary members, said pump having an outlet in a direction away from said piston; an internal passage including first and second portions; a control valve having an open position wherein pressurized fluid is directed toward a sump and a closed position wherein pressurized fluid is directed to said expandable chamber to move said piston to said second position to activate said coupling mechanism to couple the rotary members together; a check valve disposed in said casing between said outlet of said pump and said first and second portions; wherein an outlet of said check valve is simultaneously in direct fluid communication with said expandable chamber via said first portion and in direct fluid communication with said control valve via said second portion.