A cam's a projecting part of a rotating wheel or shaft that strikes a lever at one or more points on its circular path. The cam can be a simple tooth, as's used to deliver pulses of power to a steam hammer, for example, or an eccentric disc or other shape that produces a smooth reciprocating (back and forth) motion in the follower which's a lever making contact with the cam. The reason the cam acts as a lever's because the hole isn't directly in the centre, therefore moving the cam rather than… (More on Cam)