Hydraulic screw feed mechanism

Claim 1

IN A RECIPROCATING HYDRAULIC MOTOR INCLUDING MEANS FOR CONTROLLING THE SPEED OF RECIPROCATION THEREOF; A CYLINDER, A PLUNGER EXTENDING INTO THE CYLINDER, A PISTON ON THE PLUNGER IN THE CYLINDER, SAID PISTON HAVING AN ADVANCING SIDE ON THE SIDE OPPOSITE THE PLUNGER AND HAVING A RETRACTION SIDE ON THE PLUNGER SIDE THEREOF, A NUT CARRIED BY THE PISTON, A SCREW IN THE CYLINDER THREADEDLY ENGAGING SAID NUT, A DRIVE MOTOR CARRIED BY THE CYLINDER, MEANS FOR SELECTIVELY CONNECTING THE DRIVE MOTOR TO THE SCREW FOR CONTROLLING THE SPEED OF ROTATION THEREOF, AND, THEREFORE, CONTROLLING THE SPEED OF MOVEMENT OF THE PISTON AND PLUNGER IN THE CYLINDER, PRESSURE SENSITIVE MEANS BETWEEN THE CYLINDER AND SCREW SENSITIVE TO AXIAL THRUSTS EXERTED ON THE SCREW BY THE PISTON FOR DEVELOPING A SIGNAL, A SOURCE OF FLUID UNDER PRESSURE, A FIRST VALVE HAVING A FIRST POSITION WHEREIN THE SOURCE OF PRESSURE IS CONNECTED WITH THE ADVANCING SIDE OF THE PISTON WHILE THE RETRACTING SIDE THEREOF IS CONNECTED WITH EXHAUST AND HAVING A SECOND POSITION WHERE THE RETRACTING SIDE OF THE PISTON IS CONNECTED WITH THE SAID SOURCE WHILE THE ADVANCING SIDE THEREOF IS CONNECTED WITH EXHAUST, A SECOND VALVE INTERPOSED BETWEEN SAID FIRST VALVE AND THE ADVANCING SIDE OF SAID PISTON HAVING A FIRST POSITION WHERE THE CONNECTION BETWEEN THE FIRST VALVE AND THE SAID ADVANCING SIDE OF THE PISTON IS ESTABLISHED AND HAVING A SECOND POSITION WHEREIN THE SAID CONNECTION IS INTERRUPTED AND FLUID IS ENTRAPPED ON THE ADVANCING SIDE OF SAID PISTON, MEANS FOR SHIFTING FIRST AND SECOND VALVES TO THEIR RESPECTIVE FIRST POSITIONS TO INITIATE AN ADVANCING MOVEMENT OF SAID PISTON, MEANS OPERABLE DURING SAID ADVANCING MOVEMENT FOR CONNECTING THE SCREW TO THE SAID DRIVE MOTOR THEREFORE TO CONTROL THE RATE OF MOVEMENT OF THE PISTON, AND MEANS SENSITIVE TO THE SIGNAL FROM SAID PRESSURE SENSITIVE MEANS FOR SHIFTING SAID FIRST VALVE TO ITS SECOND POSITION UPON THE DEVELOPMENT OF A PREDETERMINED RESISTANCE TO MOVEMENT OF THE SAID PISTON IN ITS ADVANCING DIRECTION THEREBY TO BRING ABOUT IMMEDIATE RETRACTION OF SAID PISTON WHENEVER THE PISTON ENCOUNTERS A PREDETERMINED AMOUNT OF RESISTANCE, THERE BEING MANUALLY OPERABLE MEANS AND ALSO MEANS OPERABLE IN RESPONSE TO A PREDETERMINED ADVANCING MOVEMENT OF SAID PISTON AND PLUNGER FOR SHIFTING SAID FIRST VALVE TO ITS SAID SECOND POSITION, TO CAUSE RETRACTION OF THE PISTON AND PLUNGER, AND MEANS MANUALLY OPERABLE FOR SELECTIVELY SHIFTING SAID SECOND VALVE TO ITS SAID SECOND POSITION TO HALT SAID PISTON AND PLUNGER.