GB805288A - An hydraulic percussion tool - Google Patents

Abstract

805,288. Percussive tools. HUPPERT & CO. Ltd., C. Nov. 20, 1956 [Nov. 23, 1955], No. 35488/56. Class 124. A hydraulically operated percussive tool comprising a casing, a cylinder having a piston therein, and a striker operatable by and movable in unison with the piston has at least one pneumatic pressure accumulator coacting with the pressure liquid, a high pressure liquid conduit communicating with the working side of the piston, a second conduit, in which high and low pressure conditions alternate, communicating with the return side of the piston, the pneumatic pressure accumulator being continuously associated with the high pressure conduit and intermittently with the second conduit, the latter being in intermittent communication with a low-pressure return line to conduct pressure liquid from the return side of the piston during the working stroke. As shown, a piston 4 having a striker 5 is acted upon by pressure liquid in a blind cylinder 8 to drive it downwardly and strike the shank of a drill steel 7, rotary valves 18 and 19 driven by a hydraulic motor 20, 21 controlling the supply of pressure liquid to a space 10 (of greater crosssectional area than the cylinder 8) to return the piston. Pneumatic accumulators 13 and 15 are provided in the pressure line and return line respectively to ensure a constant liquid pressure. Starting and stopping the machine is controlled by a valve 27 which when open allows the pressure liquid to circulate and the tool is inoperative. On closing the valve 27 liquid under pressure is supplied to the cylinder 8 and with the valve 18 closing the port 47 and the valve 19 opening the port 25 the space 10 is connected to the return line and the piston moves downwardly in a working stroke. Further rotation of the valves 18 and 19 causes opening of ports 23 and 47 and closing of port 25 thus connecting the pressure liquid to the space 10 and returning the piston. The accumulator 13 is always in contact with high pressure liquid and when the valve 18 is closed is in a compressed condition but when valve 18 opens it expands and a constant pressure is maintained in the liquid. The accumulators comprise flexible containers and are charged to a predetermined pressure, e.g. high pressure accumulator 13 to 450 lbs. per sq. in. and low pressure accumulator 15 to atmospheric pressure when the liquid pressure is 800 lbs. per sq. in. on the high side and 70 lbs. per sq. in. on the low side. A detailed description of a practical embodiment of the invention is given. Figs. 2-8 (not shown).