In mechanical transmission, torque is transmitted between the shaft and the shaft. In the master-slave drive, the torque must be transmitted by a coupling or other transmission method, and with the improvement of the degree of mechanical automation and machining accuracy, especially for the use of servo motors, stepper motors, encoders and other high-precision automation. In the case of precision machinery, the coupling becomes an indispensable coupling. The reason for this is that the coupling has its own unique advantages.