There are two types of links alternating in the bush roller chain. The 1st type is internal links, having two internal plates held collectively by two sleeves or bushings where rotate two rollers. Inner links alternate with the second type, the external links, comprising two external plates held jointly by pins passing through the bushings of the internal links. The “bushingless” roller chain is similar in operation though not in structure; instead of individual bushings or sleeves holding the inner plates together, the plate has a tube stamped into it protruding from the hole which serves the same agricultural Chain purpose. This has the advantage of removing one step in assembly of the chain.
The roller chain design reduces friction in comparison to simpler designs, resulting in higher efficiency and less wear. The initial power transmission chain types lacked rollers and bushings, with both inner and outer plates held by pins which directly contacted the sprocket teeth; nevertheless this configuration exhibited incredibly rapid use of both the sprocket teeth, 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 wear over a greater area; however the teeth 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 aswell. There is even very low friction, so long as the chain is sufficiently lubricated. Continuous, clean, lubrication of roller chains is of major importance for efficient operation in addition to correct tensioning.