A power drill has a rotatable spindle extending from a power-unit housing, a chuck body rotationally fixed to the spindle, a jaw guide carried on the chuck body and rotatable relative thereto about the axis, jaws carried in the chuck body, and a pusher element rotatable about the axis in the chuck body and fixed to and bearing axially on the jaws. Screwthreads between the pusher element and the spindle is effective to move the jaws radially on rotation of the spindle about the axis relative to the guide. A coupling sleeve rotationally fixed to the jaw guide is movable between a tightening position rotationally fixed to the housing for movement of the jaws by the pusher element on rotation of the spindle and a drilling position rotationally fixed to the spindle and rotatable relative to the guide for joint rotation of the guide, jaws, and spindle.