| 摘要 |
A drill chuck has a chuck body formed with an annular row of radially outwardly directed teeth. A sleeve axially fixed but rotatable about the chuck axis on the chuck body has a plurality of angularly spaced guides holding respective radially displaceable jaws. A screwthread displaces the jaws radially toward each other on rotation of the sleeve in a tightening direction on the body and displaces the jaws radially apart on rotation of the sleeve in an opposite loosening direction. A pawl pivoted on the inner sleeve has a tip radially displaceable between an inner blocking position engaging the body teeth and allowing rotation of the sleeve on the body only in the tightening direction and an outer freeing position clear of the body teeth and permitting rotation of the sleeve on the body in both of the directions. A spring urges the pawl into the inner blocking position.
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