| 摘要 |
In a water driven down-the-hole rock drill, the rearward end of an associated hammer is provided with a drive piston reciprocable in a cylinder located adjacent the rear of the drill. The front end of the hammer is guided for reciprocation in a bearing located adjacent an anvil of a drill bit. Between the cylinder and the bearing the hammer is elongated and enlarged diametrically relative to the piston. The enlarged hammer portion reciprocates freely in a chamber formed by an outer casing of the drill. Drive water is expelled from the cylinder and flushes the hole drilled by the bit. An open ended tubular valve reciprocates to control a duct connecting the interior of the valve to coaxial through-flushing channels in the hammer and the drill bit. |
