Transmission roller chain is famous for its high strength an continuous antifatigue. It is articulated by roller link and pin link. it is interference fit between pin and outer link, bush and inner link; while clearance fit between pin and bush. the roller can roll freely around the bush for reduction of friction and wear and mitigation of impingement, which is used for driving. According to varied working conditions ,it may choose the chain with different coating treatment ,such as zinc plating ,nickel plating ,chrome plating and dacromet plating etc.