The drive shaft is a rotating body with high speed and low support, which is very important for the dynamic balance of the car. Therefore, the drive shaft of the car must be tested for dynamic balance before the car leaves the factory, and it is adjusted on the dynamic balancing machine. For front-engine rear-wheel drive vehicles, the drive shaft of the car is a very important part. The drive shaft is composed of a shaft tube, a telescopic sleeve and a universal joint, which can automatically adjust the distance between the transmission and the drive axle. The function of the universal joint is the key part on the drive shaft of the automobile, which is installed between the output shaft of the transmission and the input shaft of the drive axle final reducer. The relative position of the two shafts can be ensured, and the power is transmitted within the expected range.