When the technical condition of the automobile drive shaft becomes bad, the amplitude of bending vibration increases, the vibration is severe, and even causes the body vibration, and gives out obvious periodic sound, which is called vibration and abnormal sound. The main reasons for the vibration and abnormal sound of the driving shaft are as follows:

1, drive shaft assembly out of balance drive shaft assembly assembly assembly error beyond the limit, parts size is not accurate and in use wear and deformation will make the drive shaft along the length direction of the mass distribution is not uniform and cause the transmission imbalance. Unbalanced transmission shaft in operation will produce additional bending moment, the role of additional bending moment will not only make the match impact ring, but also enhance the bending vibration of the transmission shaft, so that the vibration and abnormal sound of the transmission shaft is more obvious.

2, universal joint damage in the use of the main damage is the cross shaft neck and end face wear and needle rolling and bearing seat hole wear. The damage of the universal joint parts makes the cross shaft swing and axial movement with loose opening, which not only makes a collision sound in the work, but also weakens the bending stiffness of the transmission shaft. The center of mass of the drive shaft is further away from the axis of rotation, thus enhancing chattering and abnormal noise.

3. The driving shaft and sliding fork damage the bending of the driving shaft shaft tube, that is, increase the amplitude of the bending vibration of the driving shaft, which can increase the centrifugal force, resulting in strong vibration and abnormal sound. Drive shaft key teeth and sliding fork keyway wear, due to loose, in the work will issue a collision sound, will also weaken the bending stiffness of the drive shaft, enhance vibration and abnormal sound.

For the universal joint drive shaft with different angular speed, in order to reduce the vibration of the drive shaft and ensure the uniform rotation of the drive axle gear, the following two conditions must be met: 1) the universal joint fork at both ends of the drive shaft should be located in the same plane; 2) the input shaft, the output shaft and the drive shaft should be equal to the Angle. Drive shaft in use, due to the drive shaft key teeth and sliding fork keyway wear, universal joint cross shaft journal and needle rolling with loose, etc., will make the first condition damage; The second condition will be destroyed by the poor installation of the drive shaft, the change of the technical condition of the elastic suspension and the wear of the input shaft and output shaft of the drive shaft, which causes the change of the installation position. With the destruction of constant speed transmission conditions, the main reduction gear of the drive axle will have impact, and cause the operation of the drive shaft is unstable, and enhance the jitter and abnormal sound.

5, drive shaft critical speed to reduce the design of the highest speed is generally 0.7 times the critical speed. However, due to the destruction of the dynamic balance of the transmission shaft, the damage of the universal joint and the looseness of the intermediate supporting bearing, the critical speed of the transmission shaft will be reduced. When the critical speed is reduced to the speed of the drive shaft, the drive shaft is easy to produce resonance in operation. When the transmission shaft resonates, the amplitude is large and the vibration is severe, which often causes the transmission shaft to break.