| 摘要 |
<p>The flow control valve has the valve element (36) pressed onto the valve seat (22) by a closing spring (38). The spring acts on a main piston (30) between two hydraulic chambers (44,42) with a control piston (50) pressed into a bore through the centre of the main piston to move hydraulic fluid under the main piston and lift the valve into the open position. Non-return valves (58) hold the valve open. The two fluid ducts between the two hydraulic chambers can be fitted with non return valves to hold the main valve open or closed as required. With a flow restriction bridging the non-return valves a time delay is obtained in which the valve is held open, or closed, for a set time.</p> |
