| 摘要 |
<p>A hammer drill includes a housing, a first ratchet fixed to the housing, a spindle rotatably supported by the housing about an axis, and a second ratchet coupled for co-rotation with the spindle. The second ratchet is engageable with the first ratchet in response to rearward displacement of the spindle to impart a hammering action on the spindle. The hammer drill further includes a thrust bearing having an arm extending away from the axis, and a selector ring having a post extending toward the arm. The selector ring is rotatable between a first position in which the post is engageable with the arm to limit the rearward displacement of the spindle and prevent engagement of the first and second ratchets, and a second position in which the post is misaligned with the arm to permit the rearward displacement of the spindle and engagement of the first and second ratchets.</p> |
