There are two types of links alternating in the bush roller chain. The initial type is inner links, having two internal plates held jointly by two sleeves or bushings upon which rotate two rollers. Internal links alternate with the second type, the external links, consisting of two external plates held together by pins passing through the bushings of the inner links. The “bushingless” roller chain is comparable in operation though not in structure; instead of separate bushings or sleeves keeping 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 external plates held by pins which straight contacted the agricultural Chain sprocket the teeth; however this configuration exhibited incredibly rapid put on of both the sprocket tooth, and the plates where they pivoted on the pins. This problem was partially solved by the development of bushed chains, with the pins holding the outer plates passing through bushings or sleeves connecting the internal plates. This distributed the wear over a greater area; however the tooth of the sprockets still wore more rapidly than is desired, from the sliding friction against the bushings. The addition of rollers surrounding the bushing sleeves of the chain and supplied rolling 
contact with the teeth of the sprockets leading to excellent resistance to use of both sprockets and chain as well. There is even very low friction, so long as the chain is definitely sufficiently lubricated. Continuous, clean, lubrication of roller chains is definitely of principal importance for efficient operation and also correct tensioning