| 摘要 |
A drill has a drill spindle centered on and rotatable about an axis and having a front externally threaded end and immediately thereadjacent a shank. A chuck element centered on the axis is formed with a forwardly open tool hole, axially therebehind with a threaded bore complimentarily engaging the spindle end, and immediately therebehind with a coaxial unthreaded bore surrounding the shank. An adjustment element is rotatable about the axis on the chuck element. One of the elements is formed with a plurality of angled guide passages and the other element is formed with a screwthread centered on the axis. Respective jaws in the passages and exposed in the tool hole each have a toothed edge meshing with the other-element screwthread so that relative rotation of the elements displaces the jaws along the respective passages.
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