There are two types of links alternating in the bush roller chain. The 1st type is internal links, having two internal plates held collectively by two sleeves or Drive Chain bushings upon which rotate two rollers. Internal links alternate with the next type, the external links, consisting of two outer plates held collectively by pins moving through the bushings of the inner links. The “bushingless” roller chain is comparable in operation though not in structure; instead of individual bushings or sleeves holding 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 in comparison to simpler designs, leading to higher efficiency and less wear. The original 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 use of both sprocket the 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 connecting the inner plates. This distributed the wear over a larger 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 surrounding the bushing sleeves of the chain and provided rolling contact with one’s teeth of the sprockets resulting in excellent resistance to wear 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 can be of main importance for efficient procedure along with correct tensioning.