IE37177B1 - Percussion apparatus - Google Patents

Abstract

1358674 Percussive tools YAMADA JUKI KK 2 Jan 1973 [25 March 1972] 276/73 Heading B4C A percussive tool comprises a hammer piston 27, 30 free to move in cylinder 21 under the influence of air cushions developed when the cylinder is reciprocated by a rotary mechanism 17, the pressure chamber above the piston being considerably greater in volume than the one below. The crank-shaft 16 shown is turned by a gear-wheel 18 driven through a flexible drive shaft by an external I.C. engine or electric motor. A chisel 31 may be resiliently mounted and struck by the hammer piston; alternatively, the impact tool may be a ramming stamp which is attached to the hammer piston. The cylinder 21 can communicate with atmosphere via ports 25, 26 when opened by the passage of the piston. During an upstroke of the cylinder 21 with the lower ports 26 closed, the air is compressed in the lower chamber until the cushion of air is such as to move the piston on its upstroke to close the upper ports 25 and compress the air trapped in the upper chamber. During the downstroke of the cylinder 21, compression of the air above the piston is completed before the piston is compelled to move downwardly on its working stroke by the compressed cushion of air. As soon as the lower ports 26 are closed, the air trapped in the lower chamber begins to be compressed. The ports may be replaced by a single large port or a slot. Handles 37 are resiliently-mounted on buffer springs 35. The rotary mechanism on the tool may be a cam or eccentric instead of the crank shown. [GB1358674A]