GB974930A - Improvements in percussion tools - Google Patents

Abstract

974,930. Percussive tools. ATLAS COPCO A.B. Jan. 3, 1961 [Jan. 5, 1960], No. 4671/64. Divided out of 957,204. Heading B4C. A percussive tool has a housing 1, a working cylinder 6 in the housing, a hammer-piston 7 reciprocable in the cylinder under the action of a pressure fluid, a working implement 16 actuated by the hammer-piston, and a distributing valve 27 arranged to distribute fluid to the portions 9, 8 of the cylinder to reciprocate the hammer-piston with rapid working strokes and slower return strokes and to vent the fluid cushions formed at the ends of the strokes. The tool may be actuated pneumatically, hydraulically or by steam pressures. A handle member 18 has guide rods 84 slidable in the housing, and engages rubber caps 83a on rods 83 of damper pistons 23 which slide in bores 24. As soon as the tool is connected at 30 to an air supply, air passes through duct 76 to chambers (not shown) leading to chambers 73 having outlets 79 larger than the inlets to the other chambers. A low pressure develops in the chambers 73 when the outlets are uncovered by the pistons so that the pistons and chambers constitute vibration damping means for the handle member. Pressure on a trigger 54 operates a valve 50 to vent a passage 89 communicating by means of a sliding tube 90 with a chamber 57 of a valve 43 to actuate the valve 43 and connect the air supply to a duct 32 and the valve 27. If the tool is lifted by the handle member, holes 92 in the tube are closed by bush 93 so that the chamber 57 is not vented, and air is not supplied to the valve 27 to reciprocate the hammer-piston. Air reaching the valve 27 when in its upper position (shown) passes through duet 97 into the portion 8 to give the hammer-piston its working strokes whilst air escapes from the portion 9 through port 99 and duct 101. The valve 27 is moved to its lower position as a port 94 is uncovered during the working strokes. With the valve 27 in its lower position air passes through port 99 to portion 9 and escapes slowly from portion 8 through duct 100 to cause the hammer-piston to make the return strokes, the valve 27 being returned to its upper position as the hammerpiston passes a port 95. The portions 8, 9 are connected to exhaust ports (not shown) as the hammer-piston passes grooves 102, 103, and the portion 9 is connected to a reservoir 105. An anvil block 11 is interposed between the hammer-piston and the implement which is held by a retainer 14.