A basic type of drill chuck has a chuck body or sleeve rotatable about an axis and formed with three angled guides equispaced about the axis. Respective jaws in the guides can bear rearwardly on an axially displaceable pusher for movement axially forward and radially together and opposite movement axially back and radially apart. The radially and axially displaceable jaws, pusher, and chuck body are all rotationally linked. An axially rearwardly projecting threaded stem on the pusher fits in a nut that is rotatable about the axis but axially fixed.
As described in German utility model 93 12 839 published 9 Dec. 1993, a key-operated driver gear can rotate this nut to move the pusher and jaws axially forward and back. In German patent 3,114,503 of E. Wezel the nut is fixed on the actual drive spindle so that normal forward rotation of the spindle relative to the chuck sleeve will move the jaws axially forward and radially inward, and opposite rotation relative to the sleeve will loosen them, so that for tightening or loosening it is necessary to relatively rotate the chuck sleeve and the drive spindle.
Such a chuck can be provided with quick-tightening action, that is the ability to tighten the jaws onto a tool or loosen them from a tool by a few turns of a part of the chuck, regardless of the size of the tool. This is done as described in German utility model 94 09 258 published 15 Sep. 1994 by providing radially displaceable coupling jaws that are carried on the nut and that can be moved between a coupling position engaging the pusher and coupling it to the actuating member, and a decoupling position permitting the actuating member and pusher to move axially relative to each other. The nut here is axially fixed in the chuck sleeve and rotated by a small key-driven gear. When the nut is rotated forward, the jaws are cammed inward into engagement with the stem so as to couple the nut to the pusher and transmit further forward movement of the nut to the pusher. When rotated backward, the jaws pull out of engagement with the pusher and free it. This movement can take irrespective of the axial position of the pusher so that a few turns in one directions tightens the chuck and a few in the opposite loosens it, regardless of the diameter of the tool shank held in the jaws.
Such a system is fairly complex and are not intuitive in operation. It is necessary to use a key for the final tightening and initial loosening of the chuck. The only real time saver is that, once the jaws and pusher are decoupled from the nut, a tool of any diameter can be pushed between the jaws which will move against spring force to accommodate the tool.
USPTO Backgrounds
USPTO Backgrounds