Wear Problems
Damage, wear, deformation, and loss of balance in the drive shaft can cause unusual noise and vibration during driving, and in severe cases, damage to related components. A "dinging" sound may be heard during starting or sudden acceleration, and the component may feel loose. If the drive axle gear is not loose, then the drive shaft is clearly loose. Loose parts are typically the universal joint cross bearing, the steel cup and flange fork, or the telescopic sleeve spline shaft and spline sleeve. Generally, the clearance between the cross shaft diameter and the bearing should not exceed 0.13mm, and the meshing clearance between the telescopic spline shaft and spline sleeve should not exceed 0.3mm. If the clearance exceeds the service limit, the component should be repaired or replaced.
If the chassis makes a "humming" sound while driving, and the sound becomes louder at higher speeds, this is generally due to wear and tear in the universal joint cross shaft and bearing, wear on the drive shaft intermediate bearing, damage to the intermediate rubber support, a loose hanger, or improper hanger positioning.
1) Traditional methods: Repairing drive shaft wear in China typically involves welding, inserting sleeves, and pitting. However, when the shaft is made of 45-grade steel (quenched and tempered), overlay welding alone can generate internal weld stresses. Under heavy loads or high-speed operation, cracks or even fractures may occur at the shaft shoulder. Stress relief annealing is difficult to perform, resulting in long processing cycles and high maintenance costs. Cast iron welding is also not ideal for HT200 shafts. Some companies with advanced repair techniques utilize brush plating, laser welding, micro-arc welding, and even cold welding, all of which often require high standards and are expensive.
2) New Repair Methods: These repair techniques are no longer common in European, American, Japanese, and Korean companies. Developed countries generally utilize polymer composite materials and nanotechnology. Polymer technologies can be operated on-site, effectively improving repair efficiency while reducing costs and intensity. The most widely used of these technologies is the Meijiahua technology system. Compared to traditional technologies, polymer composites possess the strength and hardness required of metals while also offering a yield (variable relationship) that metals lack. Through processes such as mold repair, component matching, and machining, the dimensional fit between the repaired area and the mating component can be maximized. Furthermore, the composite material's inherent advantages in compression, bending resistance, and elongation effectively absorb external impacts, significantly reducing and offsetting radial impact forces from the bearing on the shaft. This prevents the possibility of play and secondary wear caused by increased play.
Balance Problems
Symptoms and Diagnosis: When a 6x4 vehicle is heavily loaded and occasionally makes a knocking noise, especially during bumpy driving, check the center and rear axle balance shafts for displacement and interference with the driveshaft. If the noise increases with speed and is accompanied by vibration, this is generally due to an imbalanced driveshaft. This vibration is most noticeable in the cab. The driveshaft's dynamic balance imbalance should be less than 100 g/cm. Severe driveshaft dynamic balance failure can lead to damage to related components. The most common problems are cracks in the clutch housing and fatigue damage in the intermediate rubber bearings.
Solution
Screw the front wheels securely with wood, and use a jack to lift the center and rear drive axles on one side of the vehicle. Start the engine, shift into high gear, and observe the drive shaft for shimmy. Note that if the shimmy increases significantly as the revs drop, it indicates a bent drive shaft or misaligned flange.
Bent drive shafts are often caused by a bent axle tube, mostly due to vehicle overloading. Coal transport vehicles are prone to bent and broken drive shafts due to overloading and overloading. For example, some vehicles, coupled with trailers, were carrying over 60 tons of coal, and the drive shafts were severely damaged due to overloading and overloading. Despite reinforcing the intermediate drive shaft bearings and strengthening the flange forks, breakage and damage still occurred.
After replacing and straightening the drive shaft components, a balance check should be performed. The imbalance should meet standard requirements. The technical condition of the universal joint fork and drive shaft hanger should also be checked in detail. If the installation is not in compliance with the requirements, the cross shaft and roller are damaged, causing looseness and vibration, which may also cause the drive shaft to lose balance.