Clutch assembly for semiautomatic gear transmission

In an automotive transmission including a torque converter powered by an engine aboard a vehicle, a manually shiftable gear train coupled with vehicular traction wheels, and a friction clutch inserted between said torque converter and said gear train for temporarily decoupling the latter from the engine during changes in speed ratio,

• the improvement wherein said friction clutch comprises:
• a driving friction-element carrier rotatable about an axis and coupled with said torque converter for entrainment by the engine;
• a driven friction-element carrier rotatable about said axis and coupled with said gear train for powering the traction wheels during operation of the vehicle;
• a piston interposed between said driving and driven carriers, said piston forming with said driving carrier a first and a second cylinder space fluidically separated from each other, said first cylinder space having an inlet connectable to a source of hydraulic pressure fluid for moving said piston into a position of engagement of the friction elements of said carriers, said piston being provided with spring means for moving same into a position of disengagement of said friction elements upon disconnection of said inlet from said source, said driving carrier being provided with passages forming an exit port communicating with said second cylinder space;
• and
• valve means on said driving carrier responsive to fluid pressure in said first cylinder space for blocking said exit port while connecting said inlet via part of said passages to said second cylinder space whereby entering pressure fluid helps displace said piston into its position of engagement, said valve means being biased to unblock said exit port upon disconnection of said inlet from said source to vent said second cylinder space to an adjoining low-pressure area.