| 摘要 |
<p>A control unit for controlling the supply of fluid to a hydraulic jack, the control device including a main valve having a valve member normally held closed by pressure in a pressure chamber, the pressure chamber being fed with fluid through a bore in a valve member of the main valve. In one embodiment, a valve spindle slides in the bore to stop it being blocked. In another embodiment, designed to control a double-acting jack, the main valve is associated with a second similar main valve the pressure chamber of which is fed from the first main valve instead of through a bore in its valve member.</p> |
