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Drive shaft failure repair


       Wear problem

       The damage, wear, deformation, and loss of dynamic balance of the drive shaft components will cause abnormal noise and vibration when the car is driving, and will cause damage to related components in severe cases. When the car is running, it makes a "Gordon" sound when it starts or accelerates rapidly, and it clearly shows the feeling of loose parts. If it is not the loosening of the drive axle transmission gear, it is obviously the loosening of the drive shaft. The loose parts are nothing more than universal joint cross bearings or steel bowl and flange fork, the spline shaft and spline sleeve of the telescopic sleeve. Generally speaking, the cross shaft diameter and the bearing openness should not exceed 0.13mm, and the meshing gap between the telescopic spline shaft and the spline sleeve should not exceed 0.3mm. Exceeding the service limit should be repaired or replaced.

       If the chassis makes a "humming" sound while the car is running, and the higher the running speed, the louder the sound. This is generally due to the wear and tear of the universal joint cross shaft and the bearing, the wear of the intermediate bearing of the transmission shaft, the damage of the intermediate rubber support or the loose hanger, or the fixed position of the hanger.

       1) Traditional methods: Repair welding, bushing, pitting and other methods are generally used for the wear of transmission shaft in China. Will produce welding internal stress. Under heavy load or high-speed operation, cracks or even fractures may appear at the shaft shoulder. If stress relief annealing is used, it is difficult to operate, and the processing cycle is long, and the maintenance cost is high; When the material is HT200, the use of cast iron welding is not ideal. Some companies with higher maintenance technology will use brush plating, laser welding, micro-arc welding and even cold welding, etc. These maintenance technologies often require higher requirements and high costs.

       2) New repair methods for the above repair technologies are not very common in European, American, Japanese, and Korean companies. Developed countries generally use polymer composite technology and nanotechnology. Polymer technology can be operated on-site to effectively improve repair efficiency and reduce In terms of maintenance cost and maintenance intensity, the most widely used technology system is Mega Wah. Compared with traditional technology, polymer composite materials not only have the strength and hardness required by metal, but also have the retreat (variable relationship) that metal does not have. Through "mold repair", "part correspondence", "mechanical processing", etc. The process can ensure the size matching of the repaired part and the mating parts to the greatest extent; at the same time, the composite material itself has the comprehensive advantages of compression resistance, bending resistance, and elongation rate, which can effectively absorb the impact of external forces, and greatly resolve and offset the bearing The radial impact force on the shaft avoids the possibility of the gap, and also avoids the secondary wear of the equipment due to the increase of the gap.

       Balance problem

       Symptom diagnosis: When the 6×4 car is under heavy load, especially when driving bumps, it occasionally makes a knocking sound. Pay attention to check whether the balance shaft of the middle and rear axle is displaced and interferes with the transmission shaft. If the noise increases with the increase of the vehicle speed during the operation of the car, and is accompanied by jitter, this is generally caused by the loss of balance of the transmission shaft. This kind of vibration is most noticeable in the cab. The unbalance of the dynamic balance of the drive shaft should be less than 100 g. cm. Serious failure of the dynamic balance of the drive shaft will cause damage to related components. The most common are the clutch shell cracks and the fatigue damage of the middle rubber support.


       Tighten the front wheel of the car with mats, jack up the middle and rear drive axles on one side of the car; start the engine, put it in high gear, and observe the vibration of the drive shaft. During the observation, notice that when the speed drops, if the shimmy increases significantly, it indicates that the drive shaft is bent or the flange is skewed.

       The bending of the drive shaft is the bending of the shaft tube, and most of it is caused by the overload of the car. Due to overloading and overhanging of coal-carrying vehicles, more failures occurred due to bending and breaking of drive shafts. If some trucks and trailers transport more than 60 tons of coal, the drive shaft is seriously damaged due to overloading and overhanging. Although the intermediate support of the transmission shaft was strengthened and the strength of the flange fork was strengthened, the failure of fracture and damage still occurred.

       After replacing the transmission shaft components and straightening, check the balance, and the unbalance amount should meet the standard requirements. The technical condition of the universal joint fork and the transmission shaft hanger should also be checked in detail. If the installation fails to meet the requirements, the cross shaft and the roller damage will cause looseness and vibration, and the transmission shaft will also lose balance.