| 摘要 |
A spring-loaded check valve in the fluid supply line for the sink drill (12) comprises a valve cone (23) which can slide against a guide (26) so that when the valve is open, a liquid-filled region (27) is formed which is in communication with the liquid downstream from the cone via a leakage connection. The valve does not respond to pressurised fluid fluctuations during a hammer cycle, but closes quickly when the supply of pressurised fluid is cut- off. The fluid supply line is formed by the drill tube (11) and channels in the drill bit driven by the hammer are used to form outlets for the used drive fluid. |
