A tool chuck suitable for use with manual or powered impact drivers is described. The chuck comprises a body which carries a rotatable nut and a plurality of slidable jaws, driven by the rotatable nut. An anti-friction bearing is disposed between the rotatable nut and a bearing thrust ring mounted on the body. The bearing thrust ring has a plurality of detents and may cooperate with a compression spring to prevent the chuck from loosening during operation. <IMAGE>
