GB359779A - Improvements in valve for rock drills - Google Patents

Abstract

359,779. Valve-gear for rock drills. INGERSOLL-RAND CO., 15, Exchange Place, Jersey City, New Jersey, U.S.A. Dec. 3, 1930, No. 36474. Convention date, Jan. 16. [Class 122 (ii).] A rock drill has a fluidactuated lift valve S provided with a pair of flanges V, Wand a stem T which is housed in a chest O at the rear of the tool. The valve has a recess U the end of which constitutes an actuating area j, the exterior of the stem forming another area o to which pressure fluid passes through a port p. The fluid is supplied through an inlet Y, an annular passage Z, and ports X to the space between the flanges. Ports e, f in the flanges allow pressure fluid to pass to the areas g, h on the exterior of the flanges V, W respectively and to the cylinder ends during working. Fluid passes to the ends of the cylinder through a port b in a plate H closing the cylinder end and passages c, d. The ports e are larger than the ports f. An actuating area b is also provided on the flange W. When during forward motion the piston passes the exhaust port E, the pressure of the fluid on areas h, o and the front cylinder end compression on the area k move the valve forward ; the additional pressure on the area k as the supply fluid passes to the forward end of the cylinder accelerates the valve motion. An auxiliary exhaust passage r opens the end of the stem to atmosphere on the completion of the valve motion. During the return stroke, when the top of the piston passes the exhaust port E, the pressure on the area g and the compression pressure on the area j reverse the valve.