GB190423268A - Improvements relating to Pneumatic Hammers and similar Tools - Google Patents

Abstract

23,268. Tierney, J. W. Oct. 28. Percussive hand tools. -In the handle of a pneumatic hammer or other tool for riveting &c., a valve D for controlling the inlet of motive fluid through the inlet D<1> is moved by a lever D<4> against a spring D<3>. To produce the initial impulse of the piston B, the fluid passes into the chamber a and through the passage c' to the groove c<18>, whence it enters the space a' behind the piston by a duct c<19>. Part of the fluid presses against the shoulder c<x> on the slide valve C, which has two external diameters with grooves in each, and the annular groove ax is filled with the fluid through the groove c<4> and passage c<5>. When the piston has passed the groove a<x>, it is driven outwards at full pressure. A portion of the fluid in front of the piston passes into the atmosphere through ports a<8>, and on these being closed the rest passes through the ducts a<4>, a<3> to the passage c<9> in the valve-box and through passages c<11>, c<10>, c<12> into the space c<13> and finally into the air by the outlet a<5>. When the piston B passes the port a<6>, the driving-fluid passes through the passage a<7> to the recess c<16> and forces out the slide valve. The fluid from the opening D<1> then passes through the port c<7> to the groove c<6> and through the port c<8> to the passages c<@>, a<2> and forces up the piston, the exhaust at the same time taking place through the recess a<x> and passages c<5>, c<15>, a<5>. The piston on uncovering the ports a<8> continues its motion by impulse received at the beginning of the stroke. When the piston covers the recess a<x>, the fluid is forced from the space a<2> through the passage c<19> against the shoulder c<x> of the slide valve, which is driven back, the fluid behind the valve escaping through passages c<16>, a<7>, a<6>, a<8>.