Machine element

A machine element is an elementary component from which a machine is built, and the term is also used for the hardware of a machine in general. Engineers group these parts into three basic kinds: structural components such as frame members, bearings, axles, splines, fasteners, seals and lubricants; mechanisms that control movement, including gear trains, belt and chain drives, linkages, cams and followers, brakes and clutches; and control components such as switches, sensors, actuators and computer controllers. Most elements are standardized to common sizes, though custom versions are common for specialized uses. An element may be a feature of a larger part, like a screw thread, or a discrete part such as a wheel, pulley or gear. Designing machines largely means choosing and combining these elements.