| 摘要 |
<p>Pressure relief valve for hydraulic pit prop, comprises a casing, a valve seat and a valve body movable in the casing a gas cushion being provided between the valve body and the casing, adapted to bias the valve body in the direction of closure, and the gas cushion is provided inside a bellows in gastight sealing relationship on one side relative to the valve body and on the other side relative to the casing.</p> |
