| 摘要 |
A check valve for a rock drill comprises a valve plate carrying a cylindrical strainer. An insert is carried by the valve plate and is movable between valve-open and valve-closed positions. A spring biases the insert to a valve-closed position. The insert unit includes a lid which engages and covers the top of the strainer in a valve-open position, and a bottom plate which covers the valve plate in a valve-closed position to prevent cuttings from fouling the valve mechanism.
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