| 摘要 |
<p>A valve assembly is provided for use in controlling a plurality of fluid operated functions. The assembly comprises a plurality of valve members 14, each movable independently to carry out a fluid flow control function for example, a function of a hydraulic mine roof support. There are means 39 for supplying hydraulic fluid to all the valve members 14 thus tending to move all the valve members, but there is also an interposer device 18 positionable in the path of at least one of the valve members to prevent the said one of the valve members from carrying out its fluid control function, thus enabling the valve members to be selectively operable.</p> |
