There are two 
types of links alternating in the bush roller chain. The first type is internal links, having two internal plates held jointly by two sleeves or bushings upon which rotate two rollers. Internal links alternate with the next type, the external links, consisting of two external plates held together by pins passing through the bushings of the internal links. The “bushingless” roller chain is similar in procedure though not in building; instead of individual bushings or sleeves holding the inner plates collectively, the plate includes 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 in comparison to simpler designs, resulting in higher efficiency and less wear. The original power transmission chain varieties lacked rollers and bushings, with both the inner and external plates kept by pins which directly contacted the sprocket teeth; however this configuration exhibited incredibly rapid put on of both the sprocket teeth, and the plates where they pivoted on the pins. This issue was partially solved by the development 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 Stainless Steel Chain 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 leading to excellent resistance to put on of both sprockets and chain aswell. There is even very low friction, as long as the chain is certainly sufficiently lubricated. Continuous, clean, lubrication of roller chains can be of major importance for efficient operation in addition to correct tensioning.