Pneumatic driver

Claim 1

A PNEUMATIC DRIVER COMPRISING, IN COMBINATION, A CYLINDER HAVING A LOWER BORE OF ONE DIAMETER AND AN UPPER COUNTERBORE OF LARGER DIAMETER, A DOUBLE ACTING PISTON RECIPROCABLE IN BOTH OF SAID BORES, AN ANNULAR FLANGE EXTENDING BETWEEN SAID PISTON AND SAID COUNTERBORE, SAID LARGER DIAMETER BORE DEFINING AN ANNULAR CHAMBER EXTERIORLY OF SAID PISTON BELOW SAID FLANGE, THE AREA OF SAID FLANGE BEING SMALLER THAN THE AREA OF SAID BORE, SAID PISTON HAVING A CYLINDRICAL WALL DEFINING AN INTERNAL RECESS IN THE TOP OF SAID PISTON WITH UNRESTRICTED ACCESS TO THE TOP OF SAID CYLINDER AND SAID COUNTER BORE ABOVE SAID FLANGE, SAID WALL SEPARATING AND PREVENTING COMMUNICATION BETWEEN SAID RECESS AND SAID ANNULAR CHAMBER AT ALL TIMES, A FEEDER MECHANISM RECIPROCABLE SUBSTANTIALLY AT RIGHT ANGLES ONLY TO THE AXIS OF SAID LOWER BORE, A DRIVING MEMBER CONNECTED TO SAID PISTON, SAID LOWER BORE HAVING MEANS IN THE LOWER PORTION THEREOF TO VENT THE SPACE BELOW SAID PISTON, A PORT IN SAID CYLINDER ABOVE THE UPPERMOST POSITION OF SAID PISTON, A FURTHER PORT SUBSTANTIALLY POSITIONED IN THE LOWER PART OF SAID ANNULAR CHAMBER BELOW THE LOWERMOST POSITION OF SAID FLANGE, MOVABLE MEANS TO ADMIT PRESSURE FLUID TO SAID FIRST-NAMED PORT IN ONE POSITION OF SAID MEANS TO MOVE SAID PISTON IN A DRIVING STROKE AND TO EXHAUST PRESSURE FLUID FROM SAID ANNULAR CHAMBER THROUGH SAID SECONDNAMED PORT, MEANS OPERATIVELY ASSOCIATED WITH SAID VALVE MEANS TO MOVE SAID FEEDER MECHANISM IN A NON-FEEDING DIRECTION DURING SAID DRIVING STROKE AND IN A FEEDING DIRECTION UPON RETURN OF SAID VALVE MEANS TO A NORMAL RETURN POSITION FROM SAID ONE POSITION, A TRIGGER ADAPTED TO BE PRESSED AND OPERATIVELY ASSOCIATED WITH SAID VALVE MEANS TO MOVE SAID VALVE MEANS TO SAID ONE POSITION, MEANS FOR AUTOMATICALLY RETURNING SAID VALVE MEANS TO A NORMAL RETURN POSITION FROM SAID ONE POSITION WHEN SAID TRIGGER IS NOT PRESSED, SAID VALVE MEANS IN NORMAL RETURN POSITION OPERATIVELY CONNECTING THE SPACE ABOVE SAID PISTON TO EXHAUST AND SAID ANNULAR CHAMBER TO A SOURCE OF SAID PRESSURE FLUID.