GB1344182A - Percussive implement - Google Patents

Abstract

1344182 Percussive tools NIPPON PNEUMATIC MFG CO Ltd 3 May 1971 [1 May 1970 (2)] 12796/71 Heading B4C A percussive tool comprises a reciprocable hammer piston 14, 15, 20 movable on an impact stroke by compressed air and movable on a return stroke by a liquid, e.g. oil admitted to annular space 22 via a port 30 and ports 28 in a slidable valve member 19. As the piston approaches the end of its return stroke, air in the cylinder above the piston will be compressed and will, upon the valve member 46 being raised by the piston, via passage 49, act on the under surface of piston 24 integral with the slidable valve member 19 which will thus be raised to terminate supply of liquid to the space 22 and open that space to exhaust via port 27. As a consequence the air above the piston will force the latter on an impact stroke. When the head 14 of the piston passes ports 52, 54, air pressures above and below the piston 24 will be equalized and the valve member 19 will be returned to its illustrated position. A further cycle will then occur. With the piston in its illustrated position compressed air will, if the air pressure in the cylinder is below a predetermined value, flow into the cylinder from bottle 59 via a pressure regulator 61 and a check valve 60. Supply of liquid to port 30 is controlled by a manually operable ON-OFF valve (not shown).