Overview Of Cardan Shaft Balancing Issues

What is the Cardan Shaft?
Cardan shaft is an important part in the automotive transmission system. Its role is to work with the gearbox and drive axle to transfer the power of engine to the car wheels, so that the vehicle will generate driving force. For cardan shaft which in the front-engine rear-wheel drive car, it transfer the rotating of transmission to the main decelerator. 
The drive shaft can be multi pieces, such as two-piece drive shaft, three-piece drive shaft, and the joints can be connected by universal joint.
Why cardan shaft need dynamic balance?
The Cardan Shaft is a shaft that can transmit power in the universal joint transmisison unit. It's a high-speed rotating body with few supports, so its dynamic balance was very important. Usually, the drive shaft must do dynamic balance measurement before leaving factory.

Balancing problems
When the car is under heavy load, especially in the bumpy driving with occasional knocking sound, attention shall be paid to check whether the balance shaft of the middle and rear axle is out of position and interferes with the transmission shaft. If in driving, the noise increases with the increase of vehicle speed, and is accompanied by jitter, this is usually caused by the cardan shaft losing its balance. This vibration is most apparent in the driver cab. The unbalance amount of the drive shaft should be less than 100 g·cm.
Serious failure of the drive shaft dynamic balance can result in damage to related components. The most common are the crack in clutch housing and the fatigue damage of the intermediate rubber bearing.
Stuff the front wheels tightly with a mat, and also jack up the middle and rear drive axle on one side of the car; Start the engine and hung it into the high gear, and then observe the shimmy situation of the drive shaft. If the shimmy obviously increases when the rotating speed decrease, indicates that the drive shaft is bent or the flange is skewed.
Drive shaft bending are all shaft tube bending, and most of them were caused by the car overloading. Due to overloading and over-hanging for coal, there are many bending and fracture failures of the drive shaft in coal-carrying truck. 

Such as some trucks with trailer which carrying more than 60 tons of coal, the drive shaft is seriously damaged due to overloading and over-hanging. Although they strengthened the middle support  and flange fork strength, the failure of the breakage still occurs.
First, replace the drive shaft components, Second, straightening, Third, balance measuring should be carried out after straightening. And the unbalance amount should meet the standard requirements. 
The technical condition of the universal joint fork and the drive shaft hanger should also be examined in detail. If the installation didn't meet the requirements, and causes the cross shaft and the roller damaged, and finally result in the looseness and vibration of drive shaft, the cardan shaft will also be out of balance.
After the dynamic balance measurement of the drive shaft, process a convex solder joints in the balancing weight and then welding it to the drive shaft with projection welding process.
At last
JP Balancer have completely balancing solution for cardan shaft, including hard bearing and soft bearing balancing machine, which can suitable for one-piece, two-piece and three-piece drive shaft. Whether you are drive shaft manufacturer or repairer, you can find a suitable drive shaft balancing machine here for your using.