Hydraulically controlled drive system

Claim 1

A DRIVE SYSTEM COMPRISING, IN COMBINATION, DRIVE MEANS INCLUDING OUTPUT MEANS AND ADJUSTING MEANS FOR ADJUSTING THE OUTPUT TORQUE OF SAID OUTPUT MEANS; A SHAFT DRIVEN BY SAID OUTPUT MEANS AND ADAPTED TO DRIVE A MACHINE SUBJECTED TO A VARIABLE LOAD; A FIRSTR CONTROL PUMP; MEANS FOR DRIVING SAID FIRST CONTROL PUMP AT A SELECTED CONSTANT SPEED; A SECOND CONTROL PUMP; MEANS FOR DRIVING SAID SECOND CONTROL PUMP FROM SAID SHAFT; CONDUIT MEANS CONNECTING THE OUTLET OF SAID FIRST CONTROL PUMP WITH THE INLET OF SAID SECOND CONTROL PUMP AND THE OUTLET OF SAID SECOND CONTROL PUMP WITH THE INLET OF SAID FIRST CONTROL PUMP WHEREBY AN OPERATING LIQUID IS CIRCULATED THROUGH SAID CONDUIT MENS SO THAT THE PRESSURES AT SAID INLET AND OUTLET OF SAID SECOND CONTROL PUMP ARE EQUAL WHEN SAID SHAFT RUNS AT A DESIRED SPEED; AND A PRESSURE RESPONSIVE MEANS HAVING CHAMBER MEANS COMMUNICATING WITH SAID CONDUIT MEANS AT TWO POINTS LOCATED IN THE REGION OF SAID INLET AND OUTLET OF SAID SECOND CONTROL PUMP, RESPECTIVELY, SAID PRESSURE RESPONSIVE MEANS INCLUDING A MOVABLE CONTROL ELEMENT MOVING IN OPPOSITE DIRECTIONS WHEN THE PRESSURE AT ANY OF SAID POINTS EXCEEDS THE PRESSURE AT THE OTHER OF SAID POINTS, SAID CONTROL ELEMENT BEING OPERATIVELY CONNECTED TO SAID ADJUSTING MEANS SO THAT SAID OUTPUT MEANS IS ADJUSTED TO PRODUCE A GREATER OR SMALLER OUTPUT TORQUE WHEN A PRESSURE DIFFERENTIAL AT SAID POINTS IS CAUSED BY A SPEED CHANGE OF SAID SHAFT, AND THEREBY OF SAID SECOND CONTROL PUMP, DUE TO A LOAD VARIATION.