GB191012324A - Improvements in Valves for Percussive Rock Drills, Pneumatic Hammers, Pneumatic Hammer Drills, Direct Acting Pumps and Engines. - Google Patents

Abstract

12,324. Daw, A. W., and Daw, Z. W. May 19. Fluid-actuated gears. -Relates to the distribution of motive fluid in percussive rock-drills, hammers, direct-acting pumps andengines by the class of valve described in Specification 18,027/07. Referring to Figs. 1, 2, and 3, the piston valve 2 is formed with annular recesses 3, 4, and with end cylinders 5 in which work pistons 7 on the ends of the casing 1. The casing is preferably fitted with a liner 1<a> formed with a supply port 9, branches 11, 12, and exhaust ports 10, 10<a>, 13, 14. The ports 13, 14 lead from the ends of the casing 1 to the opposite ends of the main cylinder 20 by branches 13<a>, 13<b>, 14<a>, 14<b>, as shown in Fig. 2. In operation, with the valve in the position of Fig. 1, fluid is entering the left hand end of the main cylinder by the recess 3 and port 11. When the piston 15 uncovers the port 14<b>, fluid is admitted through the passage 14 to the right-hand end of the valve cylinder to throw over the valve. At the same time, the left-hand end of the valve cylinder is put in communication with exhaust by the opening-up of the passages 13, 13<a>, and 10<c> through the annular recesses 16 in the piston 15. In order to lock the valve in each operative position, ports lead from the end cylinders 5 of the valve to the recesses 3, 4, which are each alternately open to exhaust and supply. The arrangement of the cylinders 5 and pistons 7 may be reversed. In cases where the main piston is not formed with a recess 16, a small port at each end of the valve casing is open to exhaust continuously. In modifications, the valve casing is arranged at the end of, and perpendicular to, the main cylinder. The Specification describes the method of boring-out the ports and passages especially in cases where the valve casing and main cylinder are cast or forged in one piece.