Planetary reducer high precision low back gap planetary reducer in the CNC machine tool application structure is compact, small size, rigid, can produce high torque density, coaxial input and output make the design more flexible, light weight. More than 96% of the high transmission efficiency, maintenance-free, long life, modular design applications and installation is easy, positive and inverse can be applied, good thermal conductivity, not easy to temperature rise, so the best choice for CNC machine tools components.