An idler sprocket is a device used to maintain the tension in a chain or chain drive system. Often consisting of nothing more than a sprocket mounted on a spring tensioned arm, the idler sprocket pulls against the chain in a constant manner to keep the chain tight at all times.
Steel idler sprockets maintain proper chain tension, and guide the chain around obstacles and prevent excessive chain wear and vibration. You don’t need any special tightener shafts for ball bearing idler sprockets. Composite sprocket idlers require no lubrication and are corrosion resistant and wear-resistant.
The ideal installation of the idler sprocket is on the opposite side of the chain between the drive sprocket and the driven sprocket.