| 摘要 |
<p>The control assembly, with reversible switch valve, and double-action activating cylinder, with piston activated to valve position via two leads, are incorporated in a pressure-medium -activated device for opening and closing large doors, gratings or similar. The control assembly (7,12,13) is laid out so that pressure in the pipe (10) effecting closure is maintained, for the position of the piston (15) corresponding to the closure setting, even after the pressure-medium supply (4) has been de-activated or switched off. There is no need for an additional lock for securing the door or grating.</p> |
