GB1161445A - Impact Tools - Google Patents

Abstract

1,161,445. Percussive tools. WORTHING- TON CORP. 27 Sept., 1967 [27 Sept., 1966], No. 43987/67. Heading B4C. A percussive tool comprises an impact piston 36 having operative surface area 52, 53, an inlet passage 47 for supplying pressurized liquid to the surface area 53 continuously and valve means 38 for controlling the flow of liquid to the surface area 52 in order to effect a working stroke, a land 51 on the piston being adapted to close off communication between the pressurized liquid and the surface area 52 while the valve means is still positioned to supply pressurized liquid thereto. The valve means 38 is actuated, in one direction, by means of small diameter pins 62 in direct communication with the inlet passage 47 ; and, in the other direction, by means of larger diameter pins 60 communicating with the inlet passage via ports 70, 71, 72 and a bore 35 controlled by the land 51. In operation, with the apparatus in the position shown a pilot valve 40 is actuated by means of a trigger 44 so as to admit pressurized liquid from an inlet port 30 into the passage 47 and then via a passage 76, bore 37 and passage 75, to act on the surface area 52 so as to cause the piston to effect a working stroke. Towards the end of the stroke, liquid which has been acting on the pins 60 to maintain the valve 38 in the position shown, is exhausted so as to allow the valve to be moved to its other position by liquid acting on the pins 62. The valve 38 then permits the liquid acting on the surface area 52 to be exhausted via bore 35, passage 75, bore 38 and exhaust passage 79 (Fig. 4); the impact piston is then returned by liquid acting on the surface area 53. During operation of the tool only build-up of pressure in the passage 75 is relieved by means of a bumper 52 which is loaded by a spring 93 and by pressurized liquid via a passage 94. A pneumatic-piston type accumulator 48 is also connected to the inlet passage 47.