| 摘要 |
<p>1509286 Valves BENNES MARREL 28 May 1975 [31 May 1974] 23271/75 Heading F2V An hydraulic remote control system comprising a pilot valve controlling flow to a relay valve distributing fluid to a jack or the like includes port means enabling the input crosssection of the pilot line to the relay valve to be varied whilst the exhaust cross-section of the pilot line remains constant. In one arrangement a pair of pilot valves operated by a common manual lever acting on pistons 5 each have inlet and outlet ports 2, 3 and control flow of pilot fluid via respective ports 23, 24 to pistons 17, 18 at opposite ends of relay valve spool 19. Each pilot piston 5 includes radial ports 13 which when one piston is depressed variably communicate input chamber 8 with a blind bore within the piston and thence with port 3. Simultaneously the other piston 5 is raised under the action of spring 6 to fully communicate radial ports in the piston with exhaust chamber 9 connected via port 4 to drain. Thus relay spool 19 is moved, e.g. rightwards, the displaced exhaust pilot fluid discharging through restricted passage 25 in piston 18 and thence via drain line 28, in addition to the flow through ports 24 and 4. In a modification, no port 4 is provided and all pilot fluid discharge occurs via passage 25 and drain 28. In another arrangement (Fig. 4, not shown) no drains 28 are provided in the relay valve but a restricted passage (35) extends axially through the spool to permanently connect the opposing actuating chambers (31, 32). Several pilot valves may be associated with each relay valve.</p> |
