| 摘要 |
A drilling machine has a tool holder shaft on which are mounted a spring and a blocking sleeve which abuts one or the other of two eccentric abutment faces of a manually turnable member. In a first position of the manually turnable member, the spring permits movement of the shaft due to pressure against the workpiece to a first axial position in which the shaft is axially reciprocated by suitable displacement means during rotation, and performs a percussion drilling operation. In a second position of the manually turnable member, the blocking sleeve engages the shaft directly, and blocks the same in a second axial position in which the shaft is not reciprocated but only rotated during drilling, irrespective of the pressure applied by the shaft to the workpiece.
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