There are two types of links alternating in the bush roller chain. The initial type is inner links, having two internal plates held with each other by two sleeves or bushings upon which rotate two rollers. Inner links alternate with the second type, the outer links, comprising two external plates held jointly by pins passing through the bushings of the inner links. The “bushingless” roller chain is comparable in procedure though not in building; instead of separate bushings or sleeves holding the inner plates together, 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 compared to simpler designs, resulting in 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; nevertheless this configuration exhibited incredibly rapid wear of both the sprocket the teeth, and the plates where they pivoted on the pins. This problem was partially solved by the advancement of bushed chains, with the pins keeping the outer plates passing through bushings or sleeves connecting the internal plates. This distributed the put on over a greater area; however the teeth 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 provided 
rolling contact with one’s teeth of the sprockets leading to excellent resistance to wear of both sprockets and chain aswell. There is even suprisingly low friction, as long as the chain can be sufficiently lubricated. Continuous, clean, lubrication of roller chains is certainly of principal importance for efficient operation as well as correct tensioning.