| 摘要 |
A power tool includes manually operated selector means for alternately establishing rotary-hammer and hammer-only modes of operation for the associated drill bit. The attachment is in the form of an elongated member having a longitudinally extending blind bore for receiving the drill bit; retaining means are provided for releasably mounting the attachment on the drill bit. An annular shoulder defining the mouth of the blind bore is in abutting engagement with another annular shoulder, the latter being arranged to receive impact blows from the hammer mechanism of the power tool. In one embodiment, this second mentioned annular shoulder is constituted by a tappet forming part of the hammer mechanism. In another embodiment, this second mentioned annular shoulder is an integral part of the drill bit. Impact blows are transmitted to the attachment only through the area of engagement of the aforesaid annular shoulders. In one embodiment, the attachment has its working end in the form of a blunt end cylinder adapted to install concrete anchors. In another embodiment, the working end of the attachment is in the form of a chisel.
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