GB550937A - Improvements relating to pneumatically-operated tools - Google Patents

Abstract

550,937. Valves. CLIMAX ROCK DRILL & ENGINEERING WORKS, Ltd., and STEPHENS, R. DE H. ST. Feb. 28, 1942, No. 2661. [Class 135] [Also in Group XXIII] In a pneumatic rock drill provided in the back head with an automatic valve 5 through which water passes to the drilling point and which shuts off the air if the water pressure fails or falls below a predetermined amount, a separate manually-operable valve 22 is arranged in series with the automatic valve 5 in the path of flow of the air to the distributing valve 27 of the drill, whereby the air can be shut off independently of the automatic valve. Some of the water supplied to a central connection 1 is byepassed through a passage 4b to a space 17 between a fixed guide 8 and piston 11 which operates the valve 5. When the water pressure is sufficient to overcome a spring 14, the piston 11 opens the valve 5 which uncovers a ring of air admission ports 18. Air supplied by a hose 15 passes through segmental chambers 19, longitudinal passages 20, segmental spaces 19a, and the ports 18 to a chamber 21 within the manually-operable plug valve 22. When the latter is opened by the handle 30, the air passes through an outlet port 23, a passage 24, an annular space 25, and longitudinal passages 26 to the distributing valve 27. The supply of air is regulated by a spring plunger 32 engaging any one of a series of circumferential notches 33 in the valve 22. Any air or water leaking along the stem 7 of the valve 5 collects in an annular groove 9 and escapes to atmosphere through ports 10, any air-lock tending to prevent operation of the valve 5 is prevented by a bleeder passage 16 behind the piston 11, and axial holes 34 in the valve 5 balance the air pressure on its two sides.