There are two types of links alternating in the bush roller chain. The initial type is inner links, having two inner plates held jointly by two sleeves or bushings upon which rotate two rollers. Internal links alternate with the next type, the outer links, consisting of two outer plates held jointly by pins passing through the bushings of the internal links. The “bushingless” roller chain is similar in procedure though not in construction; instead of individual bushings or sleeves keeping the inner plates jointly, the plate has a tube stamped involved with it protruding from the hole which serves the same purpose. This has the advantage 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 types lacked rollers and bushings, with both the inner and outer plates held by pins which directly contacted the sprocket the teeth; nevertheless this configuration exhibited extremely rapid put on of both the sprocket teeth, and the plates where they pivoted on the pins. This issue was partially solved by the advancement of bushed chains, with the pins holding the outer plates passing through bushings or sleeves connecting the inner plates. This distributed the use over a greater area; however the the teeth of the sprockets still wore quicker than is desirable, from the sliding friction against the bushings. The addition of rollers encircling the bushing sleeves of the chain and supplied rolling contact with one’s teeth of the sprockets resulting in excellent resistance to wear of both sprockets and chain as well. There is even suprisingly low friction, so long 
as the chain is certainly sufficiently lubricated. Constant, clean, lubrication of roller chains is definitely of primary importance for efficient procedure and also correct tensioning