Abstract: A nut assembly comprises two end-to-end nuts threaded onto a screw and coupled by splines which prevent relative rotation between the nuts while permitting relative axial movement. A sleeve surrounds the nuts and is threaded onto one of the nuts. The other nut is formed with ratchet teeth adapted to fit into angularly spaced notches in the sleeve. When the sleeve is rotated relative to the nuts, it forces the nuts away from one another to take up backlash between the nuts and the screw. During such rotation, the teeth ratchet into and out of successive notches and ultimately prevent relative rotation between the sleeve and the nuts during normal service use.