Malfunction repair
Detect
In order to quickly attenuate the vibration of the frame and the body, and improve the ride comfort and comfort of the car, the car suspension system is generally equipped with shock absorbers, and the two-way-acting cylinder shock absorber is widely used in the car.
Shock absorber testing includes shock absorber performance test, shock absorber durability test, shock absorber double excitation test. Perform indicator test, friction test, temperature characteristic test, etc. for various types of shock absorbers.
1. Make the car stop after driving 10km on the road with poor road conditions and touch the shock absorber shell with your hands. 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, you can add appropriate lubricating oil, and then carry out the test. If the outer shell heats up, the shock absorber is short of oil, and enough oil should be added; otherwise, the shock absorber has failed.
Second, press the bumper firmly and then release it. If the car jumps 2 or 3 times, it means that the shock absorber is working well.
3. When the car is driving slowly and braking urgently, if the car vibrates violently, it indicates that there is a problem with the shock absorber.
Fourth, remove the shock absorber and stand it upright, and clamp the lower end connecting ring on the vise, and then forcefully pull the shock absorber rod several times. At this time, there should be a stable resistance. The resistance when pressing down, such as unstable or no resistance, may be the lack of oil inside the shock absorber or damage to the valve parts. Repair or replacement of parts should be carried out.
Repair
After determining that the shock absorber is faulty or invalid, first check whether the shock absorber is leaking or has traces of old oil leakage.
The oil seal washer and sealing washer are broken and damaged, and the oil storage cylinder head nut is loose. It may be that the oil seal and sealing gasket are damaged and invalid. Replace with new seals. If the oil leakage still cannot be eliminated, pull out the shock absorber. If you feel a hairpin or change in weight, check whether the gap between the piston and the cylinder is too large, whether the piston connecting rod of the shock absorber is bent, and the piston connecting rod Whether there are scratches or pull marks on the surface and cylinder.
If the shock absorber does not leak oil, check the shock absorber connecting pin, connecting rod, connecting hole, rubber bushing, etc. for damage, desoldering, cracking or falling off. If the above inspection is normal, the shock absorber should be further disassembled to check whether the matching clearance between the piston and the cylinder is too large, whether the cylinder is strained, whether the valve seal is good, whether the valve clack and the valve seat are tightly attached, and whether the extension spring of the shock is too soft or broken, it should be repaired by grinding or replacing parts according to the situation.
In addition, the shock absorber may have noise failure in actual use. This is mainly due to the shock absorber colliding with the leaf spring, the frame or the axle, the rubber pad is damaged or falling off, and the shock absorber dust tube is deformed, and the oil If it is caused by insufficient or other reasons, the cause shall be found out and repaired.
After the shock absorber is inspected and repaired, the performance test should be carried out on a special test bench. When the resistance frequency is 100±1mm, the resistance of the extension stroke and compression stroke should meet the requirements. For example, the maximum resistance of Jiefang CA1091′s extension stroke is 2156~2646N, the maximum resistance of compression stroke is 392~588N; the maximum resistance of Dongfeng Motor’s extension stroke is 2450~3038N, and the maximum resistance of compression stroke is 490~686N.
If there is no test condition, we can also adopt an empirical approach, that is, use an iron rod to penetrate the lower end of the shock absorber ring, which indicates that the shock absorber is basically normal.
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Post time: Dec-03-2021