| 摘要 |
<p>1,251,178. Valves. ROSS OPERATING VALVE CO. 4 June, 1970 [6 Aug., 1969], No. 27089/70. Heading F2V. Four-way valve comprises a body 12 having a central inlet port 24, a pair of work ports 25, 26 outwardly of the inlet port, and a pair of exhaust ports 27, 28 outwardly of the work ports. Three valve elements 29, 30, 31 carried by a spindle 22, 23 are of poppet type and carry closure seals 32, 36 and 41, 42. Elements 29, 31 face inwardly toward seats 33, 37 between the exhaust and work ports. Element 30 is positioned in the inlet chamber and co-operates with opposed seats 43, 44. The outer elements constitute sealed pistons of which one is biased by a constant loading pressure through a connection 35 and the other is subject to control pressure through connection 39 for selectively operating the valve between extreme positions. The middle element 30 has slight axial play on the spindle. As shown, the closure seals are all of equal diameter and element 31 is of larger piston diameter than element 29.</p> |
