Hydraulically powered drive system with pneumatic control circuit

Claim 1

IN COMBINATION: A SOURCE OF CONSTANT-PRESSURE HIGH PRESSURE FLUID AND A SOURCE OF LOW PRESSURE FLUID, A VARIABLE-SPEED FLUID MOTOR, A SUPPLY LINE BETWEEN SAID HIGH PRESSURE SOURCE AND THE MOTOR, A NORMALLY CLOSED VALVE AT THE INGRESS END OF SAID SUPPLY LINE, A MEANS WHICH OPERATES WHEN SUBJECTED TO PRESSURE TO OPEN SAID VALVE SO AS TO DELIVER FLUID FROM THE HIGH-PRESSURE SOURCE INTO SAID SUPPLY LINE, A LINE FROM THE LOW PRESSURE SOURCE FOR SUPPLYING SAID PRESSURE TO THE VALVE-OPENING MEANS, A MANUALLY OPERATED CONTROL VALVE FOR SAID LAST-NAMED SUPPLY LINE ACTING BY THE DEGREE TO WHICH IT IS OPENED TO VARIABLY GOVERN THE PRESSURE, WITHIN A RANGE THE CEILING OF WHICH IS PRESCRIBED BY SAID LOW-PRESSURE SOURCE, OF THE FLUID FED TO THE SUPPLY LINE, AND MEANS GOVERNED AUTOMATICALLY BY SAID GOVERNED VARIABLE PRESSURE WHICH OBTAINS IN THE LOW-PRESSURE SUPPLY LINE FOR DUMPING FLUID FROM THE HIGH-PRESSURE SUPPLY LINE UNTIL THE PRESSURE IN THE LATTER IS A PREDETERMINED MULTIPLE OF THE GOVERNED PRESSURE OBTAINING IN THE LOW PRESSURE SUPPLY LINE.