Device for automatic feed of cutting bit in well drilling

Claim 1

IN A WELL DRILLING APPARATUS INCLUDING A DRILL BIT CARRIED BY A DRILL STRING, A ROTARY TABLE FOR DRIVING THE DRILL STRING AND MEANS INCLUDING A HOISTING DRUM FOR RAISING AND LOWERING THE DRILL STRING, AN APPARATUS FOR CONTROLLING THE FEED OF THE DRILL STRING IN ACCORDANCE WITH THE FORCE OF GRAVITY AND THE TORQUE APPLIED TO THE DRILL STRING THROUGH THE ROTARY TABLE, SAID CONTROL APPARATUS COMPRISING A COMBINATION MOTOR-PUMP DRIVINGLY CONNECTED TO SAID DRUM AND HAVING AN INTAKE AND DISCHARGE, A LIQUID TANK CONNECTED TO SAID INTAKE, A PRESSURE RESPONSIVE VALVE CONNECTED TO SAID DISCHARGE, A RETURN PIPE FROM SAID VALVE TO SAID TANK AND A PLANETARY REDUCTION GEAR FOR DRIVING SAID ROTARY TABLE, SAID REDUCTION GEAR HAVING A HOUSING MOUNTED FOR PIVOTAL MOVEMENT IN PROPORTION TO THE TORQUE APPLIED TO THE DRILL THROUGH SAID ROTARY TABLE, WHEREBY SAID MOTORPUMP CONTROLLED BY SAID PRESSURE RESPONSIVE VALVE OPERATES AS A BRAKE TO MAINTAIN THE DOWNWARD FORCE EXERTED BY GRAVITY ON THE DRILL STRING SUBSTANTIALLY CONSTANT, SAID CONTROL APPARATUS FURTHER INCLUDING CONTROL MEANS CONNECTED TO SAID MOTOR-PUMP FOR CONTROLLING THE OPERATION THEREOF, AND MEANS DISPOSED IN THE PATH OF MOVEMENT OF SAID HOUSING TO ACTUATE SAID CONTROL MEANS FOR CONTROLLING THE OPERATION OF SAID MOTOR-PUMP AND THE FEED OF SAID DRILL STRING IN ACCORDANCE WITH THE TORQUE APPLIED TO THE DRILL STRING.