GB539124A - Improvements in or relating to valve assemblies - Google Patents

Abstract

539,124. Valves. PARKER, A. LA R. April 23, 1940, No. 7274. [Class 135] A multiple way valve having a valve member pressed into contact with its seat by fluid pressure acting on the opposite face has means for byepassing this pressure to facilitate displacement of the valve member. As shown in Fig. 5 a rotary disc valve 39 has arcuate recesses 17, 18 one of greater cross-section than the other adapted to connect a pair of ports leading to the opposite sides of a double-acting piston alternately to pressure and exhaust conduits. The valve actuating spindle 26 pivoted in the valve seat 20a carries a transverse pin 41 adapted to work with lost-motion between diametrically opposed pairs of upstanding lugs on the valve member. Inlet pressure is admitted to the back of the valve member through a port 22 and is exhausted through a port 52 under the control of a valve 43. This valve is mounted on a lever pivoted on the pin 41 and is opened against the action of a spring 44a during the initial movement of the spindle 26 by a cam surface engaging a pallet on the face end of the lever. The cam surface is formed on a plate 32 held against rotation in a cap 21 by a radial projection backing between lugs on the cap. The valve has projections adapted to co-operate with a stop pin screwed into the cap to limit its movement to 90 degrees. During the movement of the valve from one extreme position to the other the valve 43 remains open and so'relieves the pressure on the back of the valve member and also maintains a byepass connection between the supply and exhaust conduits. In the modification shown in Fig. 9, the byepassing valve is housed in a chamber formed by recesses 71, 72 in the valve member and actuating spindle respectively and is opened by depressing a main valve operating handle 83 pivoted at 82 to an arm 81 secured to the spindle 61 of the main valve. Ball catches 70 arranged in recesses on the back of the valve member co-operate with depressions in a plate 62 to hold the valve member in its adjusted position.