Commonly found in power transmission applications, shaft collars are ring-shaped plastic or metal devices that clamp around a shaft. The purpose of the collar is usually to hold motor components, gear assemblies, sprockets, bearings, and other parts in place and sometimes facilitate their proper movement. The collars may specifically locate components, keep them appropriately spaced, or limit their movement. Shaft collars may also be used to connect one end of the shaft itself to a part or surface.