There are two types of links alternating in the bush roller chain. The 1st type is inner links, having two internal plates held collectively by two sleeves or bushings upon which rotate two 
rollers. Internal links alternate with the next type, the external links, comprising two outer plates held with each other by pins moving through the bushings of the inner links. The “bushingless” roller chain is similar in procedure though not in construction; instead of individual bushings or sleeves holding the inner plates collectively, the plate includes a tube stamped involved with it protruding from the hole which serves the same purpose. It has the advantage of removing one part of assembly of the chain.
The roller chain design reduces friction in comparison to simpler designs, resulting in higher efficiency and less wear. The initial power transmission chain varieties lacked rollers and bushings, with both the inner and outer plates held by pins which straight contacted the sprocket the teeth; however this configuration exhibited extremely rapid wear of both sprocket tooth, and the plates where they pivoted on the pins. This issue was partially solved by the development of bushed chains, with the pins keeping the outer plates moving through bushings or sleeves connecting the internal plates. This distributed the wear over a larger area; however the the teeth of the sprockets still wore quicker than is attractive, from the sliding friction against the bushings. The addition of rollers around the bushing sleeves of the chain and offered rolling contact with the teeth of the sprockets leading to excellent resistance to wear of both sprockets and chain aswell. There is even very low friction, provided that the chain is certainly sufficiently lubricated. Constant, clean, lubrication of roller chains can be of primary importance for efficient procedure and also correct tensioning