| 摘要 |
2079457 9213673 PCTABS00014 An improved drilling head comprising a machine quill (2) for receiving a drill bit (1), means for rotating the machine quill (2) and thereby also the drill bit (1) received therein, hydraulic or pneumatic apparatus for exerting a downward force on the machine quill (2), and a rack (6) and pinion gear (8) for exerting a reactionary force on the machine quill (2) for regulating downward movement of the quill (2) and thereby eliminating backlash in the drilling head.
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