Hydraulic control system for variable displacement pump

Claim 1

IN A HYDRAULIC CONTROL SYSTEM FOR A VARIABLE DISPLACEMENT PUMP HAVING AN ACTUATING MEMBER FOR VARYING DISPLACEMENT, AND A HYDRAULICALLY ACTUABLE DEVICE OPERABLE BY FLUID FROM SAID PUMP: ACTUATING MEANS MOVABLE IN RESPONSE TO A SUPPLY OF FLUID UNDER PRESSURE THERETO FOR MOVING SAID ACTUATING MEMBER TO AND FROM A FIRST POSITION IN WHICH THE DISPLACEMENT OF SAID PUMP IS ZERO AND A SECOND POSITION IN WHICH SAID DISPLACEMENT IS MAXIMUM; FLUID SUPPLY AND RETURN LINES CONNECTING SAID PUMP AND SAID DEVICE; MEANS INDEPENDENT OF SAID PUMP FOR SUPPLY ING FLUID AT A CONTROL PRESSURE; VALVE MEANS FOR COMMUNICATING SAID FLUID AT CONTROL PRESSURE TO SAID ACTUATING MEANS TO MOVE SAID MEMBER TO INCREASE THE DISPLACEMENT AND HENCE OUTPUT OF SAID PUMP, AND MEANS RESPONSIVE TO THE PRESSURE OF THE OUTPUT FLUID FROM SAID PUMP IN SAID SUPPLY LINE TO COMMUNICATE SAID OUTPUT FLUID TO SAID ACTUATING MEANS TO MOVE SAID MEMBER IN THE OPPOSITE DIRECTION TO DECREASE THE DISPLACEMENT OF SAID PUMP TO A SUBSTANTIALLY ZERO-FLOW EQUILIBRIUM POSITION WHEN SAID OUTPUT PRESSURE REACHES A PREDETERMINED HIGH PRESSURE.