There are two types of links alternating in the bush roller chain. The 1st type is internal links, having two inner plates held collectively by two sleeves or bushings upon which rotate two rollers. Internal links alternate with the next type, the external links, consisting of two external plates held with each other by pins moving through the bushings of the inner links. The “bushingless” roller chain is similar in operation though not in building; instead of individual bushings or sleeves keeping the inner plates with each other, the plate has a tube stamped involved with it protruding from the hole which serves the same purpose. It has the benefit of removing one step in assembly of the chain.
The roller chain design reduces friction compared to simpler designs, leading to higher efficiency and less wear. The original power transmission chain types lacked rollers and bushings, with both the inner and outer plates kept by pins which directly contacted the sprocket teeth; however this configuration exhibited extremely rapid use of both sprocket the teeth, and the plates where they pivoted on the pins. This problem was partially solved by the advancement of bushed chains, with the pins keeping the outer plates moving through bushings or sleeves connecting the inner plates. This distributed the use over a greater area; however the 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 supplied rolling contact with the teeth of the sprockets leading to excellent resistance to wear of both sprockets and chain as well. There is even very low friction, provided that the chain is sufficiently lubricated. Constant, clean, lubrication of roller chains can be of primary importance for efficient procedure along with correct tensioning.