There are two types of links alternating in the bush roller chain. The initial type is internal links, having two inner plates held jointly by two sleeves or bushings where rotate two rollers. Internal links alternate with the second type, the external links, comprising two outer plates held jointly by pins moving through the bushings of the inner links. The “bushingless” roller chain is similar in operation though not in building; instead of separate bushings or sleeves holding the inner plates together, the plate includes a tube stamped into 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 initial 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 extremely rapid put on of both sprocket tooth, 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 Conveyor Chain linking the inner plates. This distributed the put on over a greater area; however the tooth of the sprockets still wore more rapidly than is desirable, from the sliding friction against the bushings. The addition of rollers around the bushing sleeves of the chain and offered rolling contact with the teeth of the sprockets resulting in excellent resistance to use of both sprockets and chain aswell. There is even very low friction, so long as the chain is certainly sufficiently lubricated. Continuous, clean, lubrication of roller chains is certainly of primary importance for efficient operation along with correct tensioning.