Abstract: A zero-backlash anti-friction nut construction for engagement with the threads of a screw. The device comprises a pair of nut sections having aligned through bores to receive the screw, pairs of rollers respectively carried by the sections and having generally conical tip portions engageable with the walls of the screw grooves, and bearings mounting each roller for rotation about its respective axis during such engagement. The rollers have Belleville springs urging them radially inward, and in addition, a coil spring carried by one of the sections biases the two toward one another against the action of the Belleville springs, so as to minimize looseness with the screw. The arrangement is such that the coil spring loads the nut sections sufficiently to effect slight retraction of each roller against the action of its Belleville springs. Improved performance and lowbacklash tracking of the nut sections along the screw thereby result.