Transmission with clutch having dual pressure engaging chambers

Claim 1

IN A POWER TRANSMISSION MECHANISM ADAPTED TO DELIVER DRIVING TORQUE FROM A DRIVING MEMBER TO A DRIVEN MEMBER, GEARING ESTABLISHING PLURAL TORQUE DELIVERY PATHS BETWEEN SAID DRIVING AND DRIVEN MEMBERS, CLUTCH AND BRAKE MEANS FOR CONTROLLING THE RELATIVE MOTION OF ELEMENTS OF SAID GEARING TO ESTABLISH PLURAL TORQUE DELIVERY RATIOS, SAID CLUTCH AND BRAKE MEANS INCLUDING A FIRST TORQUE DELIVERY CLUTCH THAT IS ENGAGED DURING OPERATION IN ONE SPEED RATIO, SAID CLUTCH AND BRAKE MEANS INCLUDING ALSO A SECOND CLUTCH THAT IS ENGAGED SIMULTANEOUSLY WITH SAID FIRST CLUTCH DURING OPERATION IN A SECOND SPEED RATIO, SAID FIRST CLUTCH COMPRISING A BRAKE DRUM DRIVABLY CONNECTED TO ONE OF SAID MEMBERS, FIRST FRICTION ELEMENTS CARRIED BY SAID DRUM, ANOTHER CLUTCH ELEMENT CONNECTED TO TORQUE DELIVERY PORTIONS OF SAID MECHANISM, SAID OTHER CLUTCH ELEMENT CARRYING OTHER FRICTION ELEMENTS THAT ARE ADAPTED TO ENGAGE SAID FIRST FRICTION ELEMENTS, A STEPPED DIAMETER PISTON DISPOSED IN SAID CYLINDER AND COOPERATING THEREWITH TO DEFINE A PAIR OF SEMI-ISOLATED PRESSURE CHAMBERS, MEANS FOR DISTRIBUTING PRESSURE TO ONE OF SAID CHAMBERS TO ENGAGE SAID ONE CLUTCH WITH A FIRST CLUTCH ENGAGING FORCE, AUXILIARY PASSAGE MEANS ESTABLISHING COMMUNICATION BETWEEN SAID CHAMBERS, VALVE MEANS FOR OPENING AND BLOCKING SAID AUXILIARY PASSAGE MEANS, AND A SIGNAL PRESSURE PASSAGE EXTENDING FROM FLUID PRESSURE SENSITIVE PORTIONS OF SAID OTHER CLUTCH TO SAID VALVE MEANS FOR DISTRIBUTING TO THE LATTER A PRESSURE SIGNAL FOR ACTUATING THE SAME.