Abnormal sound of transmission shaft: what should we do with abnormal sound of automobile transmission shaft?

Release Time：2020-03-23    

     Analysis of the abnormal noise of the transmission shaft, the common failures of the transmission shaft are as follows:

    (1) When the car starts or when the gear is shifted during driving, there will be a knocking sound on the transmission shaft, especially when the low-speed driving is performed in the high-speed gear.

    (2) There is no abnormal noise in the transmission shaft when the car starts, and there is a collision noise in the transmission shaft when the car is driving.

   (3) There is no abnormal noise in the transmission shaft when the car starts, but the transmission shaft 

squeaks when the car jumps.

   (4) The car keeps making noises throughout the driving process.The following is an example: a car lengthening 

car has abnormal noise when it runs at high speed. If the speed does not reach the design specification, and the

 car body vibrates when driving at high speed. Asked the reason, this car had this common fault before. After a 

continuous inspection in a personal auto repair factory, it was considered to be the abnormal noise from the

 main reducer. After that, the main reducer was disassembled and replaced. The common faults were not 

eliminated.

   Inspection result and root cause: During the road test, it is found that the abnormal sound of "Woo, Woo" 

will occur when the speed is above 60 km / h, and it is arc-shaped, and there will still be sound when jumping

 out of gear. The higher the speed of the car, the more obvious the abnormal noise and the stronger the vibration.

 In order to find out the causes of common failures, the rear axle of the car and the car were erected, and the

 high-end high-speed operation was hung, and there were still obvious abnormal sounds at a speed of about 

50 kilometers per hour. No obvious bending phenomenon of the transmission shaft was found in the low-speed

 operation. Check the interface mode of the transmission shaft, and find that the cross shaft forks on the two sides 

of the transmission shaft in the first and second sections are not in the same plane. After removing the middle 

support plate, it was found that the rolling bearing was slightly loose, the deviation of the parallelism of the 

drive shaft was within the required range, and the marks of the telescopic parts were unclear. After inspection,

 a middle support plate rolling bearing was replaced to maintain the first and second drive shafts The two sides 

of the cross shaft fork are in the same plane, and the two sides of the main drive shaft are installed in the same

 plane as the original position. During the trial operation, it was found that the abnormal noise at the speed of 

60 km / h was further relieved. There was still a humming sound at a speed of 70 km / h. The speed increased at

 any time, and the vibration was still increasing. After returning to the factory, replace the main drive shaft 

retractor with 190 ° and install it for trial operation. There is no abnormal noise and obvious vibration. The speed 

can be increased to more than 85 km / h, which proves that the common faults have been eliminated. In the 

universal drive without the main reducer. The universal transmission device is connected by a non-constant 

speed universal joint. This cross shaft must achieve two conditions to achieve a constant speed transmission 

system. Second, the driven fork of the cross shaft I is connected to the driving fork of the cross shaft II with

 the drive shaft III, and the cross shaft forks on both sides of the drive shaft are in the same plane; sixth, the 

intersection angle of the input shaft and the output shaft and the drive shaft Should be the same ie a1 = a2.

       For the next condition, it is generally determined by the car structure. In the rear axle of a car that is not 

independently suspended, the relative angle of view and position of the input shaft of the drive axle and the

 intermediate shaft and the output shaft of the transmission vary greatly due to the deformation of the

 suspension and the damage of the connecting hole of the intermediate support plate. The first condition

 can be guaranteed by the correct assembly process. During installation, the above two basic conditions must 

be ensured. If the above two conditions are not met during installation, the drive shaft will generate vibration

 and abnormal noise due to the uneven speed transmission system of the input shaft and the output shaft 

during operation. The installation of section 1 and 2 transmission shaft does not meet the requirements. In 

addition, for the main drive shaft, maintenance workers often only pay attention to keep the two cross shaft 

forks in the same plan during installation, and ignore the marks during disassembly, or do not mark the 

disassembly and assembly, although the cross shaft forks on both sides of the drive shaft are at the same 

The plan view, but it may still make the cross shaft fork 190 ° away from the original balance position, 

thereby destroying the original balance, and causing the transmission shaft to vibrate and abnormal 

noise due to the centripetal force during operation. In general, the main reason for the abnormal noise

 and vibration of the transmission system of this car is the incorrect installation of the transmission shaft.