| 摘要 |
The present invention generally relates to methods and apparatus for impact drilling. A drilling tool with a housing and a piston is provided. The drilling tool may be configured to impact while simultaneously rotating a drill head, independent from the rotation of a drill string. The drilling tool may include a rolling key assembly disposed between the housing and the piston that includes a bearing adapted to roll during a first direction of the piston and slide during a second direction of the piston. The drilling tool may include a clutch mechanism configured to rotate the drill head as the piston is directed in the first direction.
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