Control system for infinitely variable automatic transmission

Claim 1

IN A CONTROL SYSTEM FOR AN INFINITELY VARIABLE HYDROSTATIC TRANSMISSION OF THE TYPE HAVING A PUMP AND MOTOR WITH INTERCONNECTING FLUID PRESSURE AND RETURN CONDUITS, AND AN ASSOCIATED PRIME MOVER, IN COMBINATION, A CENTRIFUGAL PRESSURE GOVERNOR DRIVEN BY THE PRIME MOVER AT A SPEED DIRECTLY PROPORTIONAL TO THE PRIME MOVER SPEED, SAID GOVERNOR SERVING TO PRODUCE AN OUTPUT PRESSURE WHICH VARIES AS THE SQUARE OF SPEED FROM A MINIMUM EQUAL TO A REGULATED PRESSURE SUPPLY TO A MAXIMUM, A MODULATING VALVE CONNECTED TO THE OUTPUT OF SAID GOVERNOR, SAID MODULATING VALVE PRODUCING A PRESSURE OUTPUT SUBSTANTIALLY LINEAR WITH RESPECT TO PRIME MOVER SPEED FROM IDLING SPEED TO THE PRIME MOVER MAXIMUM, A PILOT VALVE FOR DETERMINING THE RATIO SETTING OF THE TRANSMISSION, MEANS APPLYING THE OUTPUT PRESSURE FROM SAID MODULATING VALVE TO SAID PILOT VALVE TO URGE SAID PILOT VALVE TO POSITION TO EFFECT SHIFTING OF THE RATIO IN ONE DIRECTION AND MEANS APPLYING A PRESSURE PROPORTIONAL TO PRIME MOVER THROTTLE SETTING TO URGE SAID PILOT VALVE IN THE OPPOSITE DIRECTION TO A POSITION TO EFFECT SHIFTING OF THE TRANSMISSION RATIO IN THE OPPOSITE DIRECTION.