Improved cam mechanism of low vibration pneumatic screwdriver

The utility model relates to an improved cam mechanism of a pneumatic screwdriver with low vibration, which is suitable to a clutch of an electric screwdriver or a pneumatic screwdriver, and is capable of reducing the work vibration greatly. Particularly, three groups of circular travel sections which are formed by a highest upper dead point and a highest lower dead point continuously and are wholly formed on an orbital plane above the cam body, wherein each group of the circular travel sections with the highest upper dead point and the highest lower dead point comprises an A travel section, a B travel section, a C travel section and a D travel section; in addition, a concave arc surface which provides the running tracks of steel balls is formed on the orbital plane of each travel section. Due to the structure, on one hand, the vibration state during the operation of the cam can be effectively reduced, and the whole manufacture cost of the electric screwdriver or the pneumatic screwdriver is reduced; on the other hand, the friction area between the cam body and each steel ball is enlarged, so that the service life of the cam mechanism is lengthened.