Control system for a multiple speed ratio power transmission mechanism with hydrokinetic couplings

Claim 1

IN A MULTIPLE SPEED POWER TRANSMISSION MECHANISM HAVING A GEAR UNIT WITH A POWER INPUT ELEMENT AND A POWER OUTPUT ELEMENT, A DRIVING MEMBER, A HYDROKINETIC TORQUE TRANSMITTING UNIT COMPRISING AN IMPELLER AND A TURBINE DISPOSED IN A TORUS CIRCUIT IN FLUID FLOW RELATIONSHIP, SAID IMPELLER BEING CONNECTED TO SAID DRIVING MEMBER AND SAID TURBINE BEING CONNECTED TO SAID INPUT ELEMENT, A FLUID PRESSURE SOURCE, A FLUID FEED PASSAGE EXTENDING FROM SAID SOURCE TO SAID TORUS CIRCUIT, AN EXHAUST PASSAGE COMMUNICATING WITH SAID TORUS CIRCUIT, A DRAIN VALVE MEANS IN SAID EXHAUST PASSAGE FOR SELECTIVELY OPENING AND BLOCKING THE EXHAUST FLOW OF FLUID FROM SAID TORUS CIRCUIT, A VALVE SYSTEM PRESSURIZED BY SAID SOURCE FOR CONTROLLING TH OPERATION OF SAID DRAIN VALVE MEANS INCLUDING A FIRST SIGNAL PASSAGE MEANS COMMUNICATING WITH SAID DRAIN VALVE MEANS FOR SELECTIVELY SUBJECTING THE LATTER TO FLUID PRESSURE, A LIMIT VALVE MEANS DISPOSED IN AND PARTLY DEFINING SAID FEED PASSAGE FOR CONTROLLING THE RATE OF FLUID FLOW FROM SAID SOURCE TO SAID TORUS CIRCUIT, AND A SECOND SIGNAL PASSAGE MEANS COMMUNICATING WITH SAID LIMIT VALVE MEANS FOR SUBJECTING THE LATTER TO SYSTEM PRESSURE TO ACTUATE THE SAME AND OPEN SAID FEED PASSAGE.