Fluid pressure control system and mechanism for control of vehicle road speed

Claim 1

A ROAD SPEED CONTROL SYSTEM FOR A VEHICLE HAVING AN ENGINE, SAID SYSTEM COMPRISING A SOURCE OF GOVERNOR PRESSURE REFLECTING ACTUAL VEHICLE SPEED, A SOURCE OF LINE PRESSURE WHICH IS GREATER THAN THE GOVERNOR PRESSURE REQUIRED TO ACCURATELY REFLECT ACTUAL VEHICLE SPEED, FIRST VALVE MEANS RESPONSIVE TO SAID GOVERNOR PRESSURE AND ESTABLISHING A SPEED SIGNAL VARYING IN DIRECT RELATION TO VARIATIONS IN SAID GOVERNOR PRESSURE ABOVE A PREDETERMINED GOVERNOR PRESSURE, LOCKING MEANS SELECTIVELY LOCKING SAID FIRST VALVE MEANS AGAINST FURTHER RESPONSE TO SAID GOVERNOR PRESSURE AND THEREFORE ESTABLISHING SAID SPEED SIGNAL AT A SELECTED VEHICLE SPEED AS A REFERENCE SPEED SIGNAL, SECOND VALVE MEANS DIFFERENTIALLY RESPONSIVE TO SAID GOVERNOR PRESSURE AND SAID REFERENCE SPEED SIGNAL AND MODIFYING LINE PRESSURE TO ESTABLISH A CONTROL PRESSURE REFLECTING CHANGES IN ENGINE POWER DEMAND REQUIRED TO MAINTAIN SAID GOVERNOR PRESSURE AT A FIXED PRESSURE REFLECTING AN ACTUAL VEHICLE SPEED EQUAL TO THE VEHICLE SPEED REFLECTED BY SAID REFERENCE SPEED SIGNAL, AND AN ENGINE CONTROL INCLUDING A SERVOMOTOR RECEIVING SAID CONTROL PRESSURE TO CONTROL THE VEHICLE ENGINE TO MAINTAIN THE VEHICLE SPEED AT THE SELECTED VEHICLE SPEED REFLECTED BY THE REFERENCE SPEED SIGNAL.