The precision conveyor chain, like transmission chain, consists of a series of journal bearings held in precise relationship to each other by constraining link plates. Each bearing consists of a bearing pin and bush on which the chain roller revolves. The bearing pin and bush are case-hardened to allow articulation under high pressures, and to contend with the load carrying pressure and gearing action imparted via the chain rollers. The main standards available are British Standard (BS), ISO Standard, American standard (ANSI)