There are actually two types of links alternating in the bush roller chain. The initial type is internal links, having two internal plates held collectively by two sleeves or bushings upon which rotate two rollers. Inner links alternate with the second type, the external links, Conveyor Chain comprising two external plates held collectively by pins moving through the bushings of the inner links. The “bushingless” roller chain is similar in procedure though not in structure; instead of separate bushings or sleeves holding 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 benefit of removing one step in assembly of the chain.
The roller chain design reduces friction compared to simpler designs, resulting in higher efficiency and less wear. The initial power transmission chain varieties 
lacked rollers and bushings, with both inner and external plates kept by pins which straight contacted the sprocket the teeth; nevertheless this configuration exhibited incredibly rapid put on of both the sprocket the teeth, and the plates where they pivoted on the pins. This problem was partially solved by the development of bushed chains, with the pins keeping the outer plates passing through bushings or sleeves linking the inner plates. This distributed the put on over a larger area; however the tooth of the sprockets still wore quicker than is desired, from the sliding friction against the bushings. The addition of rollers around the bushing sleeves of the chain and supplied 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 can be sufficiently lubricated. Constant, clean, lubrication of roller chains is of primary importance for efficient operation in addition to correct tensioning.