There are two types of links alternating in the bush roller chain. The initial type is internal links, having two internal 
plates held jointly by two sleeves or bushings where rotate two rollers. Internal links alternate with the next type, the outer links, comprising two external plates held together by pins moving through the bushings of the internal links. The “bushingless” roller chain is comparable in operation though not in structure; instead of separate bushings or sleeves holding the inner plates jointly, the plate includes a tube stamped into 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 inner and outer plates held by pins which straight contacted the sprocket teeth; however this configuration exhibited extremely rapid put on of both 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 keeping the outer plates passing through bushings or sleeves connecting the inner plates. This distributed the wear over a greater area; however the tooth of the sprockets still wore more rapidly than is appealing, 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 resulting in excellent resistance to put on of both sprockets and chain as well. There is even suprisingly low friction, as long as the chain is definitely sufficiently lubricated. Continuous, clean, lubrication of roller Drive Chain chains is usually of major importance for efficient procedure along with correct tensioning.