An idler sprocket is a gadget used to maintain the tension in a chain or 
chain drive system. Often consisting of nothing more than a sprocket installed on a springtime tensioned arm, the idler sprocket pulls against the chain in a continuous way to keep the chain restricted at all times. The size of the sprocket used in an idler sprocket assembly has no influence on the performance of the chain travel; however; a larger sprocket will often last longer due to the slower rate of the sprocket, which saves wear on the sprocket’s bearings. Maintenance for the idler assembly is commonly no more than an intermittent greasing of the sprocket’s bearings.
When driving a machine by chain, the strain of the chain should be kept at a continuous in order to avoid the chain coming from the drive sprockets. By setting up an idler sprocket in the get system, the chain is usually kept taut while not being over-tightened. Operating a chain in an over-limited condition can lead to premature bearing and chain failure while an idler sprocket positioned in the machine is usually a method to greatly extend the life of the chain, sprockets and the bearings on the machine’s sprocket shafts.
The ideal installing the idler sprocket is on the contrary side of the chain between your drive 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 both principal sprockets in a form like the letter B. This design will allow the pulleys to pull the chain hard without hindering the idler in any way as the drive chain passes over the sprocket. If a condition occurs which requires the drive to exert excess strain on the drive chain, the idler will flex against the chain, allowing it to expand while remaining in contact with the travel sprockets.
While the vast majority of idler sprockets are manufactured of steel, many components are used to produce an idler sprocket. Many poly or composite sprockets have already been used with great success plus some wooden sprockets have also been used on some machinery without concern. Many machines, so that they can reduce the wear on the drive chain, use an light weight aluminum, cast iron or steel sprocket coated in a nylon materials. The metallic hub enables the idler sprocket to stay very strong while the nylon covering is mild on the chain links.