A concrete mixer is a machine that mixes cement, sand and gravel aggregates and water into concrete mixtures. It is mainly composed of mixing drum, feeding and discharging mechanism, water supply system, prime mover, transmission mechanism, frame and supporting device. According to the working nature, it can be divided into batch type (batch type) and continuous type; according to the stirring principle, it can be divided into self-falling type and forced type; according to the installation method, it can be divided into fixed type and mobile type; According to the structure of the mixing drum, it is divided into pear type, drum type, double cone, disc vertical shaft type and circular groove horizontal shaft type.

2. The mixer should implement secondary leakage protection. After the power supply is turned on before going to work, it must be carefully checked, and it can be used only after the test transfer of the empty car is deemed qualified. During the trial operation, it should be checked whether the rotating speed of the mixing drum is appropriate. In general, the speed of the empty car is slightly faster than that of the car (after loading) by 2~3 revolutions. If the difference is large, the ratio of the driving wheel to the transmission wheel should be adjusted.