Patent ID: 7562596

Claim:
A fixed torque preload piece radially positioned between two nuts of a ball screw, and a clearance left between the nuts and the preload piece, the fixed torque preload piece being characterized in that: the preload piece is annular-shaped and is formed with at least three through holes located in an axial direction of the two nuts, at least three threaded holes are formed in an outer periphery of the preload piece and arranged in a radial direction thereof, and the threaded holes are vertical to and in communication with the through holes; at least three adjusting members each has an abutting surface formed at an end thereof, each of the adjusting members is moveably inserted in the respective threaded holes such that the abutting surface faces the through holes of the preload piece; at least three elastic members, each of which is received in each of the threaded holes such that an end of each of the elastic members is connected to each of the adjusting members; at least three adjusting screws, each of which is screwed in each of the threaded holes and serve to abut against the elastic members; and at least two steel balls are received in each of the through holes, at least one steel ball is disposed at either side of the respective through holes such that the steels ball protrude into a clearance between the nuts and the preload piece, one end of the respective steel balls abuts against the abutting surface of the adjusting members and another end of the respective steel balls abuts against the nuts.