Fluid pressure expansible rotary drill bits

Claim 1

IN A ROTARY DRILL BIT TO BE LOWERED IN A WELL BORE ON A ROTARY DRILL STRING: A BODY; CUTTER MEANS MOUNTED ON SAID BODY FOR EXPANSION LATERALLY OF SAID BODY; A MANDREL LONGITUDINALLY MOVABLE RELATIVE TO AND IN SAID BODY; COENGAGEABLE EXPANDER MEANS ON SAID MANDREL AND CUTTER MEANS; UPPER AND LOWER CYLINDERS ON SAID BODY; UPPER AND LOWER PISTONS ON SAID MANDREL MOVABLE IN SAID UPPER AND LOWER CYLINDERS, RESPECTIVELY; SAID UPPER CYLINDER INCLUDING A CYLINDER WALL; SAID LOWER CYLINDER INCLUDING A CYLINDER WALL INTEGRAL WITH SAID UPPER CYLINDER WALL AND AN ANNULAR CYLINDER HEAD SEPARATE FROM SAID LOWER CYLINDER WALL AND SURROUNDING SAID MANDREL BETWEEN SAID PISTION; MEANS DETACHABLY SECURING ONE OF SAID PISTONS TO SAID MANDREL TO PERMIT DISPOSITION OF SAID CYLINDER HEAD ON SAID MANDREL BETWEEN SAID PISTON; MEANS DETACHABLY SECURING SAID CYLINDER HEAD TO SAID LOWER CYLINDER WALL; AND MEANS FOR DIRECTING FLUID UNDER PRESSURE INTO SAID UPPER AND LOWER CYLINDER ABOVE SAID UPPER AND LOWER PISTON, RESPECTIVELY, FOR SIMULTANEOUS ACTION ON SAID PISTON AND CYLINDERS TO RELATIVELY SHIFT SAID MANDREL DOWNWARDLY IN SAID BODY AND EXPAND SAID CUTTER MEANS OUTWARDLY.