There are actually two types of links alternating in the bush roller chain. The 1st type is inner links, having two internal plates held collectively by two Stainless Steel Chain sleeves or bushings where rotate two rollers. Inner links alternate with the next type, the outer links, comprising two outer plates held together by pins passing through the bushings of the internal links. The "bushingless" roller chain is comparable in operation though not in construction; instead of separate bushings or sleeves keeping the inner plates together, the plate has a tube stamped involved with it protruding from the hole which serves the same purpose. This has the advantage of removing one part of assembly of the chain.
The roller chain design reduces friction compared to simpler designs, leading to higher efficiency and less wear. The initial power transmission chain types lacked rollers and bushings, with both inner and outer plates held by pins which directly contacted the sprocket teeth; however this configuration exhibited extremely rapid put on of both sprocket the teeth, and the plates where they pivoted on the pins. This issue was partially solved by the development of bushed chains, with the pins holding the outer plates passing through bushings or sleeves linking the internal plates. This distributed the put on over a larger area; however the tooth of the sprockets still wore quicker than is attractive, from the sliding friction against the bushings. The addition of rollers surrounding the bushing sleeves of the chain and offered rolling contact with one's teeth of the sprockets resulting in excellent resistance to wear of both sprockets and chain aswell. There is even very low friction, as long as the chain can be sufficiently lubricated. Continuous, clean, lubrication of roller chains can be of main importance for efficient operation in addition to correct tensioning.