Pneumatic reducer

The utility model relates to a pneumatic motor retarder, shell terminal of which is provided with an output shaft, inner of which is provided with an airway; the airway is provided with impellers; the impellers and the output shaft are coaxially positioned; tail of the shell is provided with an air inlet and an aid outlet; a planet retarder is connected between an impeller shaft and the output shaft. In the utility model, a multi stage planet retarder is arranged between the impeller shaft and the output shaft; moreover, the impeller shaft, the multi stage planet retarder and the output shaft are coaxially positioned, thus the utility model is compact in structure and excellent in retardment effect; as a three stage retarder is arranged in the shell, thus length of the complete machine is lengthened, the pneumatic motor is away from a high temperature environment, and the pneumatic motor service life is enhanced. Through utilization of the planet retarder, the utility model is excellent in retardment effect a