There are two types of links alternating in the bush roller chain. The initial type is internal links, having two internal Auto Chain 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 outer plates held together by pins passing 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 keeping the inner plates jointly, 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 kept by pins which straight contacted the sprocket 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 advancement of bushed chains, with the pins holding the outer plates passing through bushings or sleeves connecting the internal plates. This distributed the put on over a greater area; however the tooth of the sprockets still wore more rapidly than is appealing, from the sliding friction against the bushings. 
The addition of rollers encircling 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 aswell. There is even very low friction, provided that the chain is definitely sufficiently lubricated. Continuous, clean, lubrication of roller chains can be of principal importance for efficient procedure along with correct tensioning.