| 摘要 |
A valveless-type down-the-hole hammer drill which has an inner tube extending from the upper end of the hammer body into a central opening in a cutter bit reciprocably mounted in a chuck on the opposite end of the hammer body. High pressure fluid is supplied to the interior of the inner tube and a piston surrounding the inner tube has internal surfaces controlling connection of a port to chambers above and below the piston. The external surface of the piston controls connection of these chambers to an exhaust port A valve sleeve on the chuck coacts with the piston in this respect. |
