There are actually two types of links alternating in the bush Conveyor Chain roller chain. The first type is internal links, having two internal plates held jointly by two sleeves or bushings upon which rotate two rollers. Inner links alternate with the second type, the outer links, comprising two outer plates held jointly by pins moving through the bushings of the inner links. The “bushingless” roller chain is similar in procedure though not in construction; instead of separate bushings or sleeves keeping the inner plates jointly, the plate has a tube stamped into it protruding from the hole which serves the same purpose. This has the benefit of removing one step in assembly of the chain.
The roller chain design reduces friction in comparison to simpler designs, leading to higher efficiency and less wear. The original power transmission chain varieties lacked rollers and bushings, with both the 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 problem was partially solved 
by the advancement of bushed chains, with the pins keeping the outer plates moving through bushings or sleeves linking the inner plates. This distributed the put on over a larger area; however the the teeth of the sprockets still wore quicker than is desired, from the sliding friction against the bushings. The addition of rollers surrounding the bushing sleeves of the chain and supplied rolling contact with one’s teeth of the sprockets resulting in excellent resistance to use of both sprockets and chain aswell. There is even very low friction, provided that the chain is definitely sufficiently lubricated. Constant, clean, lubrication of roller chains can be of major importance for efficient procedure as well as correct tensioning.