A cam is a rotating or sliding piece in a mechanical linkage used especially in transforming rotary motion into linear motion. The cam can be a simple tooth, as is used to deliver pulses of power to a steam hammerfor example, or an eccentric disc or other shape that produces a smooth reciprocating back and forth motion in the followerwhich is a lever making contact with the cam. The cam can Cam s com seen as a device that rotates from circular to reciprocating or sometimes oscillating motion.
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. These diagrams relate angular position, usually in degrees, to the radial displacement experienced at that position. Displacement diagrams are traditionally presented as graphs with non-negative values.
A simple displacement diagram illustrates the follower motion at a constant velocity rise followed by a similar return with a dwell in between as depicted in figure 2. However, the most common type is in the valve actuators in internal combustion engines. Here, the cam profile is commonly symmetric and at rotational speeds generally met with, very high acceleration forces develop.
Ideally, a convex curve between the onset Cam s com maximum position of lift reduces acceleration, Cam s com this requires impractically large shaft diameters relative to lift.
Thus, in practice, the points at which lift begins and ends mean that a tangent to the base circle appears on the profile. This is continuous Cam s com a tangent to the tip circle. The most commonly used cam is the cam plate also known Cam s com disc cam or radial cam  which is cut out of a piece of flat metal or plate.
A once common, but now outdated, application of this type of cam was automatic machine tool programming cams. Each tool movement or operation was controlled directly by one or more cams. Instructions for producing programming cams and cam generation data for the most common makes of machine were included in engineering references well into the modern CNC era.
This type of cam is used in many simple electromechanical appliance controllerssuch as dishwashers and clothes washing machines, to actuate mechanical switches that control the various parts.
A cylindrical cam or barrel cam is a cam in which the follower rides on the surface of a cylinder. In the most common type, the follower rides in a groove cut into the surface of a cylinder. Cam s com cams are principally used to convert rotational motion to linear motion parallel to the rotational axis of the cylinder. 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 Cam s com 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.
Applications include machine tool drives, such as reciprocating saws, and shift control barrels in sequential transmissionssuch as on most modern motorcycles.
A special case of this cam is constant leadwhere the position of the follower is linear with rotation, as in a lead screw. The purpose and detail of implementation Cam s com 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. The output is radial to the cylinder. These were once common for special functions in control systems, such as fire control mechanisms for guns on naval vessels  and mechanical analog computers.
An example Cam s com a cylindrical cam with two inputs is Cam s com by a duplicating lathe, an example of which is the Klotz axe handle lathe,  which cuts an axe handle to a form controlled by a pattern acting as a cam for the lathe mechanism.
A face cam produces motion by using a follower riding on the face of a disk. 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. A face cam of this type generally has only one slot for a Cam s com on each face. In some applications, a single element, such as a gear, a barrel cam, or other rotating element with a flat face, may do duty as a face cam in addition to other purposes.