GB817873A - Sliding gate valve - Google Patents

Abstract

817,873. Valves. SANGSTER, O. B. July 20, 1956, No. 22604/56. Class 135. In a sliding gate valve connecting aligned passageways 12, 14 in a valve body 10, a screw-actuated sliding valve stem 44 carries a pair of channel-shaped plates 126 forming valve members which are pressed apart to engage apertured valve seat discs 22, by a spring 142. The valve members are movably carried on, and spring-pressed downwardly on, an extension 114 of the valve stem 44 by spring-embraced bolts 138 which loosely extend through conical apertures in projections on the stem and allow both rocking and vertical movements of the valve members relative to the valve stem. The extension 114, Fig. 7, has longitudinal notches 116 to receive V-shaped guides on the valve body, and two pairs of ribs 120 with inclined upper surfaces, Fig. 2, engaging correspondingly inclined lugs on the valve members 126. The inclined upper surfaces move the members 126 laterally from their seats as the valve stem rises. Similarly, inclined outer surfaces on the ribs 120 press the members 126 against their seats as the valve is finally closed. The valve seat discs 22 and walls of the bore 16 in the valve body 10 are slightly inclined to the axis of the valve stem, and bevel scraper edges are provided on the lower ends of the members 126. The outward movement of the members 126 under the action of spring 142 is limited by a slotted retainerplate 144. The upper part of the valve body 10 is flanged and bolted to a flanged bonnet 30 with the interposition of a stuffing-box plate 32 slidably supporting the valve stem 44, the plate 32 carrying a conical scraper sleeve 54. Packing 48 in the plate 32 is compressed by the bevelled lower end of a ring 56 adjusted by two or more screws 64 engaging the ring through antifriction means such as a single ball seated in the bottom of each screw. The screws 64 pass through bores and stuffing-boxes in the top of the bonnet 30, the bores preferably being of conical, oval or other shape providing exaggerated clearance facilitating adjustment of the screws. The upper end of the valve stem 44 is threaded to engage a screwed part 78 of an actuating shaft 74 having a hand wheel 76. A collar 80 on the shaft 74 is supported between ball-bearing assemblies in the bormet 30, a closure plate for the bearing being secured by a plate 96 and interposed packing member. Either or both sides of the bonnet 30 are provided. with removable cover-plates giving access to the chamber therein, the chamber being filled with lubricant which may be arranged in a circulating system. In order to allow lubricant to enter the valve stem 44 the bore in the ring 56 through which the stem passes is conical, thereby providing clearance, and transverse passages are formed in the wall of the upper end of the stem. A cup-shaped member 108 on the stem 44 carries a resilient packing-ring co-operating with the scraper 54 to form additional sealing means when the valve is fully open so that the packing 48 may be replaced without danger of leakage.