There are two types of links alternating in the bush roller chain. The first type is inner links, having two internal plates held with each other by two Drive Chain sleeves or bushings where rotate two rollers. Inner links alternate with the next type, the outer links, comprising two external plates held collectively by pins passing through the bushings of the internal links. The “bushingless” roller chain is similar in procedure though not in construction; instead of separate 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. This has the advantage of removing one part of assembly of the chain.
The roller chain design reduces friction in comparison to simpler designs, leading to higher efficiency and less wear. The original power transmission chain varieties lacked rollers and bushings, with both inner and outer plates kept by pins which directly contacted the sprocket teeth; nevertheless this configuration exhibited extremely rapid wear of both the sprocket teeth, and the plates where they pivoted on the pins. This issue was partially solved by the advancement of bushed chains, with the pins keeping the outer plates passing through bushings or sleeves linking the internal plates. This distributed the use over a greater area; however the teeth of the sprockets still wore quicker than is desired, 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 use of both sprockets and chain as well. There is even suprisingly low friction, as long as the chain is usually sufficiently lubricated. Continuous, clean, lubrication of roller chains is certainly of primary importance for efficient procedure along with correct tensioning