Pneumatic impact tool

Claim 1

IN A PNEUMATIC IMPACT DEVICE COMPRISING A BARREL HAVING A CYLINDER-LIKE CHAMBER THEREIN AND ADAPTED TO HAVE THE SHANK OF AN IMPACT TOOL SLIDABLY INSERTED INTO THE FORWARD END OF THE CHAMBER THEREIN, A STRIKER MEMBER PNEUMATICALLY RECIPROCABLE WITHIN SAID BARREL CHAMBER FOR IMPARTING IMPACT BLOWS TO THE END OF A TOOL SHANK EXTENDING INTO THE FORWARD END OF SAME, SAID BARREL HAVING A GENERALLY LONGITUDINALLY EXTENDING PASSAGE WITH ITS FORWARD END COMMUNICATING WITH THE FORWARD END OF SAID BARREL CHAMBER, AND SAID BARREL HAVING EXHAUST PORT MEANS ARRANGED TO BE OPENED AND CLOSED BY THE STRIKER MEMBER UPON RECIPROCATION OF THE SAME, THE IMPROVEMENT COMPRISING, A VALVE BLOCK MOUNTED IN THE REAR END OF SAID BARREL AND CHARACTERIZED BY A GENERALLY CYLINDRICAL FORWARD PORTION FITTED WITHIN AND CLOSING THE REAR END OF SAID BARREL CHAMBER AND BY AN ENLARGED DIAMETER REAR PORTION FITTED AGAINST THE REAR END OF SAID BARREL, SAID VALVE BLOCK HAVING A GENERALLY VERTICALLY DISPOSED TRANSVERSE GROOVE FORMED IN THE UPPER PORTION OF SAID FORWARD PORTION THEREOF, WHICH GROOVE COOPERATES WITH THE INSIDE WALL OF SAID BARREL TO DEFINE AN ENCLOSED SPACE, SAID VALVE BLOCK HAVING FIRST PASSAGE MEANS EXTENDING FROM THE FORWARD FACE OF SAID GROOVE AND COMMUNICATION WITH THE REAR END OF SAID BARREL CHAMBER, SAID VALVE BLOCK HAVING SECOND PASSAGE MEANS EXTENDING FROM THE REAR FACE OF SAID GROOVE AND COMMUNICATING WITH THE REAR END OF SAID GENERALLY LONGITUDINAL PASSAGE FORMED IN SAID BARREL, SAID BARREL HAVING PASSAGEWAY MEANS ADJACENT THE REAR END THEREOF AND COMMUNICATING WITH THE PERIPHERY OF SAID GROOVE TO ALLOW FLUID UNDER PRESSURE FROM A PRESSURE SOURCE TO BE ADMITTED TO SAID ENCLOSED SPACE, A PRESSURE ACTUATED VALVE LOOSELY DISPOSED IN SAID ENCLOSED SPACE AND HAVING A THICKNESS LESS THAN THE DISTANCE BETWEEN THE FORWARD AND REAR FACES OF SAID GROOVE, SAID VALVE BEING SHIFTABLE BETWEEN POSITIONS AGAINST THE REAR AND FRONT FACES OF SAID GROOVE FOR ALTERNATELY CLOSING SAID SECOND AND FIRST PASSAGE MEANS THEREBY TO DIRECT AIR UNDER PRESSURE INTO THE REAR AND FRONT ENDS OF SAID BARREL CHAMBER, RESPECTIVELY, TO RECIPROCABLY PROPEL SAID STRIKER MEMBER FORWARDLY AND REARWARDLY IN SAID BARREL CHAMBER WHEREBY SAME DELIVERS IMPACT BLOWS TO A TOOL SHANK EXTENDING INTO THE FORWARD END OF THE BARREL, SAID VALVE BEING CONTAINED IN SAID ENCLOSED SPACE SOLELY BY REASON OF THE ENGAGEMENT OF SAID FORWARD PORTION OF THE VALVE BLOCK WITH THE REAR END OF SAID BARREL CHAMBER.