There are two types of links alternating in the bush roller chain. The 1st type is inner links, having two inner plates held collectively by two sleeves or bushings upon which rotate two rollers. Inner links alternate with the second type, the external links, comprising two outer plates held jointly by pins moving through the bushings of the internal links. The “bushingless” roller chain is similar in procedure though not in building; instead of separate bushings or sleeves holding the inner plates with each other, 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, leading to higher efficiency and less wear. The initial power transmission chain types lacked rollers and bushings, with both the inner and outer plates held by pins which directly contacted the sprocket tooth; nevertheless this configuration exhibited incredibly rapid wear of both the sprocket teeth, and the plates where they pivoted on the pins. This problem was partially solved by the development of bushed chains, with the pins agricultural Chain keeping the outer plates moving through bushings or sleeves linking the inner plates.
This distributed the use over a larger area; however the teeth 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 leading to excellent resistance to wear of both sprockets and chain as well. There is even suprisingly low friction, so long as the chain is sufficiently lubricated. Continuous, clean, lubrication of roller chains is usually of main importance for efficient operation as well as correct tensioning.