Chuck

摘要

A chuck includes a generally cylindrical body having a nose section and a tail section. A plurality of jaws are movably disposed with respect to the body to and away from the chuck's axial bore. A generally cylindrical sleeve is in driving communication with the jaws. The sleeve engages the body or the jaws by a first set of interengaged threads so that relative rotation between the first threads drives the jaws toward or away from the chuck axis. The sleeve engages the body or the jaws by a second set of interengaged threads so that relative rotation between the second threads drives the jaws toward or away from the chuck axis. The first thread set defines a first pitch so that when the jaws close, the first threads rotationally lock in the closing direction. The second thread set defines a second pitch that is higher than the first pitch so that when the jaws close, the second threads are relatively rotatable in the closing direction.