An idler sprocket is a device used to keep up the strain in a chain or chain drive system. Often consisting of only a sprocket installed on a spring tensioned arm, the 
idler sprocket pulls against the chain in a continuous manner to keep the chain limited all the time. How big is the sprocket used in an idler sprocket assembly has no effect on the performance of the chain drive; however; a more substantial sprocket will often last longer due to the slower rate of the sprocket, which saves use on the sprocket’s bearings. Maintenance for the idler assembly is often no more than an intermittent greasing of the sprocket’s bearings.
When traveling a machine simply by chain, the strain of the chain should be kept at a continuous to avoid the chain approaching from the travel sprockets. By installing an idler sprocket in the get program, the chain can be kept taut without being over-tightened. Operating a chain in an over-restricted condition can lead to premature bearing and chain failing while an idler sprocket positioned in the machine is usually a way to greatly lengthen the life span of the chain, sprockets and the bearings on the machine’s sprocket shafts.
The ideal installation of the idler sprocket is on the opposite side of the chain between the get sprocket and the driven sprocket. The application should place the idler sprocket ready which has the sprocket pressing or pulling the chain towards itself as it loops the two main sprockets in a form like the letter B. This style will allow the pulleys to draw the chain hard without hindering the idler at all as the drive chain passes over the sprocket. If a condition occurs which needs the travel to exert surplus pressure on the drive chain, the idler will flex against the chain, allowing it to expand while staying in contact with the drive sprockets.
While the the greater part of idler sprockets are manufactured of steel, many components are used to produce an idler sprocket. Many poly or composite sprockets have been used in combination with great achievement plus some wooden sprockets have also been applied to some machinery without issue. Many machines, so that they can reduce the wear on the drive chain, use an aluminum, cast iron or steel sprocket coated in a nylon materials. The metallic hub enables the idler sprocket to remain very strong while the nylon covering is usually soft on the chain links.