A mechanism driven by the rotary motion or reciprocating motion of a cam to perform a prescribed reciprocating motion or swing. Cams have curved contours or grooves, including disk cams, cylindrical cams and moving cams. The groove curve of cylindrical cam is a spatial curve, so it belongs to spatial cam. The follower is in point contact or line contact with the cam, including roller follower, flat bottom follower and tip follower. The follower of the tip can keep contact with any complex cam profile and realize any movement, but the tip is easy to wear, which is suitable for low-speed mechanisms with small transmission force. In order to keep the follower always in contact with the cam, a spring or gravity can be used. Grooved cam can make the follower transmit definite motion, and it is a positive cam. Generally speaking, cams are movable, but there are also driven cams or fixed cams. Most cams have only one degree of freedom, but there are also wedge cams with two degrees of freedom. The cam mechanism has a compact structure, which is most suitable for occasions requiring intermittent motion of the follower. Compared with similar hydraulic and pneumatic mechanisms, it is reliable in motion, so it is widely used in automatic machine tools, internal combustion engines, printing presses and textile machinery. However, the cam mechanism is easy to wear and has noise, and the design of high-speed cam is more complicated and the manufacturing requirements are higher.