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Animated functional principle of a cam
Cams on the printing unit of a table calculating machine

A cam (engl. Cam ) is a machine element for controlling of uneven movements in a purely mechanical basis. The functional unit of cam and lever is also called a cam gear . It is primarily a component of machines . The cam disk usually consists of a flat disk with a non-uniform edge and is set in a uniform rotation . The movement resulting from the rotation of the disc is picked up from its edge via a spring-loaded lever and used to control technical processes such as switching operations . Instead of a spring, a second control disk or a disk with a groove can be used to hold the guide roller on the cam disk, as shown in the adjacent picture.

The cam is used in machine tool and textile machine construction and, in a modified form, as a cam on the camshaft in combustion engines . A special form of this machine element is the Maltese cross gear .


  • In contrast to coupling gears , the functional relationship between the input and output movement can be adapted exactly as required.
  • Almost all (continuous and differentiable) curve geometries can be implemented. So you can realize complex functions as they can result from measured values.
  • inexpensive
  • very reliable due to the simple structure


  • The power transmission is limited due to the linear contact.
  • At high speeds, the contact lever can lift if the spring forces are not sufficient to achieve the necessary accelerations. This problem is eliminated by using closed cams. The contact roller runs in a milled path instead of on an outer contour and is guided on both sides.
  • Cam disks cannot be reprogrammed and therefore only have a limited area of ​​application. In today's mechanical engineering , they are increasingly being replaced by electrical controls. Electronic systems can thus also be optimized much better.