When the technical condition of the automobile transmission shaft deteriorates, the amplitude of the bending vibration increases, the vibration is severe, and even the body is shaken, and an obvious periodic sound is emitted, which is called vibration and abnormal sound. The automobile transmission shaft is intensified with the increase of the vehicle speed, and the main reasons for the vibration and abnormal noise of the transmission shaft are as follows.

1. The drive shaft assembly is out of balance

Excessive assembly error of the drive shaft assembly, inaccurate part size and wear deformation during use can cause uneven distribution of the mass of the drive shaft along the length direction, resulting in unbalanced transmission. Unbalanced drive shafts will generate additional bending moments during operation. The effect of additional bending moments will not only impact the impact of the fittings, but also enhance the bending vibration of the drive shaft, making the vibration and abnormal noise of the drive shaft more obvious. .

2. Universal joint damage

The main damages in the use of the universal joint are the wear of the cross shaft journal and end face and the wear of the needle roller and the bearing housing. The damage of the universal joint parts causes the cross shaft to cooperate with the loose shaft to generate the swing and the axial sway, which not only makes a crash sound during the work, but also weakens the bending rigidity of the drive shaft. The center of mass of the drive shaft is further offset from the axis of rotation, enhancing vibration and noise.

3. Transmission shaft and sliding fork damage

The bending of the shaft of the transmission shaft, that is, increasing the amplitude of the bending vibration of the transmission shaft, can increase the centrifugal force, thereby causing strong vibration and abnormal noise. The drive shaft key and the sliding fork keyway are worn out. Due to the loose fitting, the impact sound will be generated during the work, and the bending rigidity of the drive shaft will be weakened, and the vibration and abnormal noise will be enhanced.

4. The installation position of the two ends of the drive shaft changes.

For the unequal-speed universal joint drive shaft, 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 forks at both ends of the drive shaft should be in the same plane;

2) The two angles of the input shaft, output shaft and drive shaft should be equal. When the drive shaft is in use, the drive shaft key and the sliding fork keyway are worn out, and the universal joint cross shaft journal and the needle roller are loosely matched, which may cause the first condition to be destroyed; and the transmission shaft is poorly mounted and the elastic suspension technology is in a state of being broken. The change and the input shaft and output shaft of the drive shaft are worn to change the mounting position, etc., and the second condition is destroyed. With the destruction of the constant speed transmission condition, the drive axle main reduction gear will be impacted, and the drive shaft will be unstable, and the jitter and abnormal noise will be enhanced.

5. The drive shaft critical speed is reduced

The maximum speed of the drive shaft design is generally 0.7 times the critical speed. However, due to the damage of the dynamic balance of the transmission shaft, the damage of the universal joint and the looseness of the intermediate support bearing, the critical speed of the transmission shaft is reduced. When the critical speed is reduced to the speed of the drive shaft, the drive shaft is prone to resonance during operation. When the drive shaft resonates, the amplitude is the largest and the vibration is severe, which often causes the drive shaft to break.