| 摘要 |
A fluid actuated percussion rock drill comprising a hollow wear sleeve (12) and a piston (14) slidingly disposed within the wear sleeve. Drive (58) and return pressure surfaces (32) bias the piston between drive and return positions, respectively. A high pressure port (18) is included. A return chamber (22) is exposed to the return pressure surface (32). A drive chamber (36) is exposed to the drive pressure surface (58). A pressure sensitive valve (42) is movable between an open and a closed position. When the valve (42) is in the open position, the high pressure port (18) is connected to the drive chamber (36). The valve means (42) includes a first valve pressure surface (48) for exposure to the drive chamber and a second pressure surface (46) for exposure to the high pressure port. A third valve pressure surface (50) is exposed to an outlet pressure port (54). The volume of fluid travels between the high pressure port (18) and the drive chamber (36) when the valve (42) is in an open position and can be limited as desired for different drill applications. The use of the valve (42) to control the high pressure into the drive chamber (36) also results in a condition which is more desirable in a rock drill. The condition allows the high pressure port (18) to be disconnected to the drive chamber (36) for most of the piston return stroke, but to stay connected for most of the piston drive stroke.
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