There are two types of links alternating in the bush roller chain. The 1st type is inner links, having two internal plates held jointly by two sleeves or Leaf Chain bushings upon which rotate two rollers. Internal links alternate with the second type, the outer links, consisting of two outer plates held collectively by pins moving through the bushings of the inner links. The “bushingless” roller chain is similar in operation though not in structure; instead of separate bushings or sleeves holding the inner plates with each other, the plate includes a tube stamped into it protruding from the hole which serves the same purpose. This has the benefit of removing one step in assembly of the chain.
The roller chain design reduces friction in comparison to simpler designs, leading to higher efficiency and less wear. The initial power transmission chain types lacked rollers and bushings, with both inner and external plates kept by 
pins which straight contacted the sprocket teeth; nevertheless this configuration exhibited extremely rapid use 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 keeping the outer plates passing through bushings or sleeves connecting the inner plates. This distributed the use over a greater area; however the teeth of the sprockets still wore quicker than is desirable, from the sliding friction against the bushings. The addition of rollers surrounding the bushing sleeves of the chain and supplied rolling contact with one’s teeth of the sprockets leading to excellent resistance to put on of both sprockets and chain aswell. There is even very low friction, so long as the chain is certainly sufficiently lubricated. Constant, clean, lubrication of roller chains is certainly of major importance for efficient procedure as well as correct tensioning.