In order to quickly attenuate the vibration of the automobile frame and the automobile body and improve the driving smoothness and comfort, the automotive suspension system is commonly equipped with the shock absorber; at present, the bi-directional action telescopic shock absorber is mostly widely used in automobiles. 
The shock absorber is wearing parts, and whether the shock absorber can normally work will directly affect the driving smoothness and the life spans of other components, so that you must always keep the shock absorber in a good working state. You can check the working state of the shock absorber by the following methods.
1. When the automobile runs 10km on a bumpy road and stops, touch the shell of the shock absorber by hands, if the shell is not hot enough, it means that there is no resistance in the shock absorber, and the shock absorber doesn’t work. You must add a proper amount of lubricating oil and test it again, if the shell is hot, it means that the oil in the shock absorber is insufficient, you must add enough oil, otherwise, the shock absorber is ineffective;
2. Forcibly press down the bumper, and then release it, if the automobile bounds for 2 to 3 times, it means that the shock absorber is in a good working state;
3. When the automobile is of emergency braking while running at a low speed, if the automobile is greatly vibrated, it means that there is something wrong with the shock absorber;
4. Remove the shock absorber, erect it, clip the connecting ring at the lower end to bench table, forcibly pull up and press down the shock absorbing rod for several times, at this time, you can sense stable resistance, and the pulling-up (resetting) resistance should be greater than the pressing-down resistance; if the resistance is unstable or doesn’t exist, it is quite possible that the oil in the shock absorber is insufficient or valve parts are damaged, you should repair or replace the damaged parts.
After you confirm the shock absorber has a problem or is completely ineffective, you should check oil leakage of the shock absorber first.
Oil seal gaskets and seal gaskets are broken, and the nuts on the cover of the oil storage cylinder are loosened. It is possible that the oil seal and seal gaskets are damaged, and you should replace them with new ones. If the oil leakage still exists, you should pull out the shock absorber, if you feel resistance or uneven weight, you further check the gap between the piston and the cylinder, the bending of the connecting rod of the piston of the shock absorber and scratches on the surface of the connecting rod of the piston and the cylinder.
If the shock absorber doesn’t leak oil, you should check whether connecting pins, connecting rods, connecting holes, rubber liners, etc. of the shock absorber are of damage, unsoldering, breakage or falling off; if no problem is found, you should further check the shock absorber: whether the clearance fit between the piston and the cylinder is too big, whether the cylinder is damaged, whether the valves are well sealed, whether the valve flaps and the valve holders are closely contacted and whether the stretching spring of the shock absorber is too flexible and easily broken, you must repair or replace them according to actual conditions.
In addition, in actual use, the shock absorber will make noise, the main causes are that: the shock absorber bumps the steel plate springs, automobile frame or shafts, the rubber cushions are of damage or falling off, the dustproof cylinder of the shock absorber is deformed, the oil is insufficient, etc. you must find the true cause and solve it.
After repairing and maintenance, the shock absorber must undergo working performance tests on a special test table, and when the resistance frequency is 100±1mm, the resistances in the stretching stroke and the compression stroke should be in line with regulations, it means that the shock absorber can normally work.