Using Idlers Idlers are used to take up slack, change direction of transmission, or for clutching action. Idler failure usually occurs when the bearing fails due to lack of lubrication or foreign particles. Idlers with precision ground double sealed bearings usually will last longer than other types. Use bushings to reduce idler bores. If bushing is too tight to insert by hand, gently tap with hammer USING SUPPORT UNDER INNER RACE OF BEARING. Bushings are available with or without shoulders.