摘要 |
A percussor assembly having a gas inlet passageway, a gas outlet passageway, a gas sealing means therebetween, and a percussion member which is moved in response to gas pressure from the gas inlet passageway overcoming the gas sealing means, which gas pressure is then vented through the gas outlet passageway, includes a valve member for closing the gas inlet passageway when the gas pressure is vented through the gas outlet passageway.
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