Cams used for function generation may have grooves that require several revolutions to cover the complete function, and in this case, the function generally needs to be invertible so that the groove does not self intersect, and the function output value must differ enough at corresponding rotations that there is sufficient material separating the adjacent groove segments.A common form is the constant lead cam, where displacement of the follower is linear with rotation, such as the scroll plate in a scroll chuck.
A cylinder may have several grooves cut into the surface and drive several followers.
Cylindrical cams can provide motions that involve more than a single rotation of the cylinder and generally provide positive positioning, removing the need for a spring or other provision to keep the follower in contact with the control surface.
Face cams may also be used to reference a single output to two inputs, typically where one input is rotation of the cam and the other is radial position of the follower. These were once common is mechanical analog computation and special functions in control systems.
A face cam that implements three outputs for a single rotational input is the stereo phonograph, where a relatively constant lead groove guides the stylus and tone arm unit, acting as either a rocker-type (tone arm) or linear (linear tracking turntable) follower, and the stylus alone acting as the follower for two orthogonal outputs to representing the audio signals.
The purpose and detail of implementation influence whether this application is called a cam or a screw thread, but in some cases, the nomenclature may be ambiguous.
Cylindrical cams may also be used to reference an output to two inputs, where one input is rotation of the cylinder, and the second is position of the follower axially along the cam. These were once common for special functions in control systems, such as fire control mechanisms for guns on naval vessels A face cam produces motion by using a follower riding on the face of a disk.A common example is the traditional sash window lock, where the cam is mounted to the top of the lower sash, and the follower is the hook on the upper sash.In this application, the cam is used to provide mechanical advantage in forcing the window shut, and also provides a self-locking action, like some worm gears, due to friction.A common example is the camshaft of an automobile, which takes the rotary motion of the engine and translates it into the reciprocating motion necessary to operate the intake and exhaust valves of the cylinders.Certain cams can be characterized by their displacement diagrams, which reflect the changing position a roller follower (a shaft with a rotating wheel at the end) would make as the cam rotates about an axis.The most common type has the follower ride in a slot so that the captive follower produces radial motion with positive positioning without the need for a spring or other mechanism to keep the follower in contact with the control surface.