mecanism

A mechanism is a system of moving parts that transmits, transforms, or distributes motion and force to achieve a specific function. Mechanisms are central to machines and can be found in engineering, biology, and social systems.

Mechanical mechanisms consist of rigid bodies joined by joints and guided by constraints, producing planned motion. Classic examples include levers, inclined planes, screws, wedges, pulleys, gears, and linkages such as the four-bar. Cam-and-follower and rack-and-pinion arrangements are also mechanisms.

In biology, mechanisms describe how processes operate at various scales, from molecular motors like myosin converting chemical energy to motion, to signaling cascades and motor control in organisms.

In technology and design, mechanism analysis uses kinematics to describe motion without considering forces, while dynamics adds forces. Degrees of freedom, constraints, and mobility are key ideas; Gruebler's equation relates the number of links to mobility in planar mechanisms.

The term originates from French mécanisme, from Greek mechane “device” via Latin mechanismus. In English, mechanism is standard; mecanism appears rarely, often as variant spelling or in non-English contexts. In economics, mechanism design studies institutions that lead to desired outcomes given agents' information.