The coupling between WGP drum gear and brake disc in the workplace, two relative angular displacements, periodic tooth surface sliding of internal and external gears relative to the shaft will inevitably lead to tooth wear and power consumption. Therefore, the combination of gears needs good state and sealing operation. The radial size of the toothed joint is large and the load capacity is large. It is usually used to support transmission under low speed and heavy load. High precision dynamic balance gear coupling can be used for high speed transmission.