GB868920A - Piston valve - Google Patents

Abstract

868,920. Valves. SHAFER, H. J. Sept. 8, 1959 [Nov. 28, 1958], No. 30600/59. Class 135. A piston valve has aligned cylinder inlet and outlet ports 11, 12, Fig. 3, controlled by a piston 20 with a through port 22, resilient seal rings 21 around its ends, longitudinal lubricant grooves 40A straddling the outlet in closed position and split at 25, 26 longitudinally intermediate its ends transversely to the through port to compensate for distortion of the cylinder due to expansion or contraction. The piston is moved between open, Fig. 3, and closed position, Fig. 6, by pressure applied to its ends via passages 18. Lubricant is supplied in all positions of the piston from passage 43A to a longitudinal groove, to a piston groove 41A connecting the upper ends of the longitudinal grooves 40A and to a cylinder groove 42A coming opposite the lower ends of the longitudinal grooves in the valve closed position. The lubricant also passes through a piston passage 48A to a piston groove 49A at the lower end of the piston, whereby the cylinder below the outlet is lubricated. In the closed position the outlet, or both outlet and inlet, is surrounded by a lubricant seal and in opening, none of the seal rings and grooves passes over the outlet or inlet openings so that lubricant cannot be blown out of the grooves. By turning a stem 31, which acts as an indicator of the valve position, a further stem 29 turns a wedge screw 28 to force apart the halves on either side of the split and increase the sealing or lock the valve in one position. The piston is prevented from turning by stud 23 entering a piston slot 24.