| 摘要 |
A keyless chuck for fastening or releasing a tool, in which a plurality of oblique holes are formed in a body, jaws are inserted into these holes, and a nut engaging with rear portions of the jaws is rotated in a normal or a reverse direction so that the jaws either advance or retreat. This keyless chuck is provided with a grip member loosely fitted around the outer periphery of the body, a pair of opposed groups of lugs provided on the nut and the grip member and capable of engaging with or disengaging from each other, and at least one spring provided on one of the groups of engaging portions and adapted for constantly urging this group of engaging portions toward the other. If the grip member is fixed, the nut is rotated in the opposite direction relative to the body so as to make the jaws advance or retreat, thereby fastening or releasing the tool. If, in the fastening operation, the torque exceeds a certain value, the groups of engaging portions are disengaged and are again engaged with each other by the spring so that the nut is rotated impulsively, thereby further increasing the fastening force. |
