Concrete mixer drum gear ring - comprises plastic segments with tapped metal inserts having non-round flanges

摘要

The concrete mixer drum gear ring is screwed to the mating flanges of the top and bottom drum halves. It consists of segments, each having an undercut boss at one end engaging in a mating recess in the next one open towards the flanges, near which a screw engages in a tapped hole in the segment. - The segments (10) are of plastics, and the tapped holes are formed in metal inserts (20) embedded in the plastics. The inserts each have two non-round larger diameter flange sections and a narrower shank between. The flanges can be slightly proud of the adjacent segment surfaces. - The design is simple to manufacture, avoiding wrong fitting of the insert in the plastics mould and giving the necessary strength where the screws engage.