There are actually two types of links alternating in the bush roller chain. The first type is inner links, having two internal plates held jointly by two sleeves or bushings where rotate two rollers. Internal links alternate with the next type, the external links, comprising two external plates held together by pins passing through the bushings of the inner links. The “bushingless” roller chain is comparable in procedure though not in structure; instead of individual bushings or sleeves holding the inner plates collectively, the plate has a tube stamped into 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 varieties lacked rollers and bushings, with both inner and external plates kept by pins which directly contacted the sprocket the 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 Conveyor Chain solved by the advancement of bushed chains, with the pins holding the outer plates moving through bushings or sleeves linking the internal plates. This distributed the wear over a greater area; however the tooth 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 the teeth of the sprockets leading to excellent resistance to wear of both sprockets and chain as well. There is even very low friction, so long as the chain is certainly sufficiently lubricated. Constant, clean, lubrication of roller chains is usually of main importance for efficient procedure and also correct tensioning.