Air disc brake slack adjuster

The present invention discloses an air disc brake slack adjuster, comprising a positioning pin, double screw, a mandrel, the mandrel spacer, the core holder, an elastic spacer, shaft ring, dial sleeve, ball bushing , a spring, a one-way needle bearing, locking fingers, circlip, and internal splines of the sleeve, the sleeve and the bush are open dial hemispherical grooves, the ball is placed hemispherical groove, the one-way cylindrical and needle roller bearings with internal splines of the sleeve, the inner spline mandrel sleeve internal splines with the external splines, the one-way needle bearing outer ring with an interference fit bushing, said dial the mandrel sleeve with clearance, said clearance fit with the mandrel sleeve, one end of the spring against the bushing, and the other end against the locking piece, the clamping spring clamping mandrel in the mandrel groove end the locking plate against the mandrel with internal threads, the stud is externally threaded screw, and both threaded engagement. The present invention can automatically adjust the brake lining and the brake disc gap, simple structure, reliable performance.