| 摘要 |
A self-tightening hammer-drill chuck has a chuck body centered on and rotatable about an axis, a guide rotatable about the axis on the body, and a plurality of jaws radially displaceable on the guide and engaged with a screwthread of the body so that rotation of the guide in a forward tightening direction on the body moves the jaws radially together and opposite rotation moves them apart. A ring formed with an annular row of teeth is axially nondisplaceable on the bodies and angularly spaced abutment formations fixed on the guide are engageable with the ring. A tightening spring urges the ring angularly in the forward direction on the guide. A holding sleeve axially displaceable on the body has an annular row of teeth meshable in a locking position with the teeth of the ring. A return spring urges the holding sleeve axially into the locking position. Front and back abutments operatively effective on the body and holding sleeve permit only limited angular movement of the holding sleeve on the body and define relative to the forward tightening direction front and back end positions of the holding sleeve on the body. A cam surface operatively engageable with the holding sleeve axially displaces the holding sleeve into the freeing position when engaged with either of the front and back abutments and for displacement of the holding sleeve into the locking position when between the front and back abutments. |
