| 摘要 |
<p>The operating arm (6) of the butterfly valve (7) is terminated in a fork (60) which has one branch (61) longer than the other (62). A counterweight (80) is also fitted to the valve. Below the valve, on the outside of the pipe, is a hydraulic cylinder (2) supported between the brackets (11,12). The cylinder is opened by upstream water pressure via a connecting pipe (5) and closed by a return spring (4). During normal operation, the hydraulic force in the cylinder overcomes the compressive force of the spring and allows the forked operating arm catch-plate (3) to move freely to the right to keep the valve open.</p> |
