GB1343857A - Pressure-medium operated percussion or impact apparatus - Google Patents

Abstract

1343857 Power hammers MOELVEN BRUG A S 17 May 1972 23203/72 Heading B3H [Also in Divisions B4-B5] A percussive tool, e.g. a hammer, includes a striker piston having an axial groove in its cylindrical surface and fluid pressure chambers in the cylinder at opposite ends of the piston, the groove extending partway along the piston to open into one of the chambers. The piston is rotated to bring the groove alternately into communication with pressure and exhaust conduits. Grooves may extend from opposite ends of the piston to communicate with both chambers. In one arrangement, Fig. 4, applied to a drill, grooves 11, 12 communicating with upper and lower chambers 9, 10 alternate round the piston which, as it reciprocates is carried to rotate in one direction only. This is achieved by splined extensions 28, 29 sliding in matching nuts 30, 31 permitted to rotate in opposite directions only by pawl and ratchet means, Fig. 5 (not shown). Rotation is imparted to the drill holder via a sliding connection 34, 35. In other arrangements, the piston and drill holder are integral and rotated by a motor (1) on the upper end of the piston-rod through a splined connection, Fig. 1 (not shown). The drill holder may be separate and rotated by a separate motor 22, Fig. 3 (not shown). In another embodiment, Fig. 6, the piston ends are of different areas and the grooves communicate only with the chamber 37 at the larger end. The small end chamber 38 is in constant connection with pressure fluid but its influence will only raise the piston when the upper chamber 37 is opened to exhaust.