| 摘要 |
<p>1289995 Valves MARTONAIR Ltd 11 Aug 1970 [26 Aug 1969] 42403/69 Heading F2V [Also in Division F1] In a fluid operated piston valve having a housing 11 through which open a plurality of ports A to E and a piston 10 through which extend three transverse passages, movement of this piston to the upper position, shown, is effected by the selective application of fluid pressure to a port 13. When in this upper position fluid applied to port C is communicated, via one of the piston passages, to a further housing port F wherefrom it passes into a tube 16 restricted at 17. Tube 16 communicates both with a manually operable venting valve 18 and with a housing port 12. With valve 18 open to atmosphere, the pressure within port 12 is rendered insufficient to impart any movement to the piston, whereas closure of the valve causes a consequential pressure build-up in port 12 and hence downward movement of the piston 10 to its other operative position (Fig. 2B, not shown). Such downward movement is accompanied by an interruption of the communication between the supply to port C and the passage 16 and hence in the prevention of any unnecessary pressure forces acting upon the piston end most proximate to port 12.</p> |
