| 摘要 |
A chuck for retaining the shank of a tool bit or accessory, having a fixed diameter, inserted in a central channel at a distal end of said chuck, comprising at least one torsion spring mounted axially within a housing and having an inner dimension and shape comparable to said shank's outer dimension and shape, and mechanical means for winding and unwinding said torsion spring to respectively grip or release the shank, said winding being in a rotational direction consistent with a normal operating rotational direction of the chuck such that the shank tends to further wind said torsion spring for further self-tightening in normal operation.
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