The Genuine Wrap Spring clutches and brakes provide hundreds of simple motion processes that can be controlled through three basic control functions: overrunning, start-stop, and single revolution. These pre-packaged, pre-assembled units are as easy to select as they are to install. The basic wrap spring clutch consists of three elements: an input hub, an output hub, and a spring whose inside diameter is slightly smaller than the outside diameter of the two hubs. When the spring is forced over the input and output hubs, rotation wraps it down tightly on the hubs, positively engaging them. The greater the force of rotation, the more tightly the spring grips the hubs. As a result, a spring clutch or brake will not slip.