Abstract: 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.

Abstract: A keyless chuck comprises a plurality of jaws slidably fitted respectively in bores formed in a body. A substantially cylindrical, first operating component is mounted on the body rotatably and axially movably, and is provided with female threads in engagement with male threads on the respective jaws. A substantially cylindrical, second operating component is mounted on the first operating component for angular and axial movement. A cam device is arranged between the second operating component and an end member fixedly mounted to the rear end of the body. When the second operating component is angularly moved in a first direction, the cam device moves the second operating component forwardly to cause at least one projection provided on the second operating component to move forwardly the first operating component and the jaws threadedly engaged therewith.