Torque converter, lock up clutch, master clutch and operator control to provide cushion engagement

Claim 1

A POWER TRANSMISSION COMPRISING A HYDRAULIC TORQUE CONVERTER AN OIL ACTUATED FRICTION PLATE CLUTCH PROVIDING A CONNECTION BETWEEN A LOAD AND THE CONVERTER OUTPUT, A PRESSURE LIQUID SOURCE, A FIRST PRESSURE REGULATING VALVE COMMUNICATING WITH THE SOURCE, FIRST AND SECOND OIL CIRCUIT MEANS PROVIDING OUTLETS OF THE FIRST PRESSURE REGULATING VALVE, THE FIRST CIRCUIT MEANS INCLUDING THE CONVERTER AND DISCHARGING OVER THE CLUTCH PLATES FOR COOLING THEREOF AND THE SECOND CIRCUIT MEANS SUPPLYING ENGAGING PRESSURE TO THE CLUTCH, A SECOND PRESSURE REGULATING VALVE HAVING ONE END SUBJECTED TO PRESSURE FROM THE SECOND CIRCUIT MEANS AND ITS OPPOSITE END EXPOSED TO OIL FLOW IN THE FIRST CIRCUIT MEANS ON THE DISCHARGE SIDE OF THE CONVERTER, AND OPERATOR CONTROLLED MEANS FOR VARYING THE POSITION OF THE FIRST PRESSURE REGULATING VALVE TO DETERMINE THE APPLICATION OF SELECTED PRESSURES TO THE CLUTCH INCLUDING THE MAXIMUM ENGAGING PRESSURE, THE SECOND PRESSURE REGULATING VALVE BEING ARRANGE TO ESTABLISH IN THE CONVERTER A BASIC PRESSURE LOWER THAN AND WHEN THE MAXIMUM PRESSURE IS APPLIED TO THE CLUTCH.