Common Repair Methods for Suspension Shock Absorber Failure After Commercial Vehicle Modification

In order to quickly attenuate the vibration of the frame and body and improve the smoothness and comfort of the vehicle, the vehicle suspension system is generally equipped with shock absorbers. At present, double-acting cylinder shock absorbers are widely used in automobiles. It affects the stability of the car's driving and the service life of other parts, so we should always keep the shock absorber in good working condition. The following methods can be used to check whether the shock absorber is working well.

1. Stop after driving 10km on a road with poor road conditions and touch the shock absorber housing with your hand. If it is not hot enough, it means that there is no resistance inside the shock absorber and the shock absorber does not work. At this time, appropriate lubricating oil can be added before the test. If the shell is hot, there is a lack of oil in the shock absorber, and sufficient oil should be added; otherwise, the shock absorber will fail.

2. Press the bumper hard and then release it. If the car jumps 2~3 times, it means that the shock absorber is working well.

3. If the vehicle vibrates violently when driving at low speed and emergency braking, it means that there is a problem with the shock absorber.
4. Remove the shock absorber, place it vertically, clamp the lower connecting ring on the vise, and pull and press the shock absorber rod several times. At this time, there should be stable resistance. The resistance to pull up should be greater than the resistance to press down. If the resistance is unstable or there is no resistance, it may be that the oil in the shock absorber is insufficient or the valve components are damaged. Repair or replace the parts.
After determining that the shock absorber has a problem or failure, check whether the shock absorber is leaking oil or has traces of old oil leakage.
The oil seal gasket and sealing gasket are broken and damaged, and the oil storage cylinder cover nut is loose. The oil seal and sealing gasket may be damaged and fail, and a new seal should be replaced. If the oil leakage still cannot be eliminated, pull out the shock absorber. If you feel the hairpin or different weight, further check whether the gap between the piston and the cylinder is too large, whether the shock absorber's piston connecting rod is bent, and whether there are scratches or pulls on the surface of the piston connecting rod and the cylinder.
If the shock absorber has no oil leakage, check whether the shock absorber connecting pin, connecting rod, connecting hole, rubber sleeve, etc. are damaged, falling off, cracked or falling off. If the above inspection is normal, the shock absorber is further disassembled to check whether the clearance between the piston and the cylinder is too large, whether the cylinder is tight, whether the valve seal is good, whether the valve disc and the valve seat are tightly matched, and whether the shock absorber telescopic spring is too soft or broken. Repair by grinding or replacing parts according to the situation.

In addition, the shock absorber will make noises in actual use, mainly due to the collision between the shock absorber and the leaf spring, frame or shaft, damage or shedding of the rubber pad, deformation of the shock absorber dust cylinder and insufficient oil. The cause should be found and repaired.

After the shock absorber is inspected and repaired, the working performance test should be carried out on a special test bench. When the resistance frequency is 100±1mm, the resistance of its extension stroke and compression stroke should meet the regulations. For example, the liberation resistance of CA091 in the extension stroke is 2156~2646N, and the resistance of the compression stroke is 392~588N; the extension stroke resistance of Dongfeng Motor is 2450~3038N, and the compression stroke resistance is 490~686N. If there is no test condition, we can also adopt the empirical method, that is, insert an iron rod into the lower ring of the shock absorber, step on both ends with both feet, put both hands on the ring and turn it back and forth 2 to 4 times. There is great resistance when pulling up, and it is effortless when pressing down. And the tensile performance has been restored compared with before repair, and there is no empty feeling, which means that the shock absorber is basically normal.