To understand why a shock absorber is needed, try to ride without it...
In order for the car not to perceive all the bumps on the road, some kind of elastic element is necessarily used in the suspension of the car. Usually a spring is used. In addition to the spring, a spring can be used, but this is already a complete archaic. Other Spring Alternatives - Air Suspension "Citroen" or hydropneumatic suspension "Rover", that run on compressed gas. But back to the spring. When driving on the road, the car begins to sway, and this is unacceptable. The main task of the shock absorber is to dampen these vibrations, or dampen them.
All shock absorbers work according to this principle: inside the shock absorber cylinder there is a piston rod, which "walks" In oil. Oil during the operation of the shock absorber flows through a special hole in the piston. This creates the necessary resistance to the movement of the rod. Also, the shock absorber should have a capacity (compensatory chamber) with compressed gas (air or nitrogen). A piston moves inside the shock absorber and displaces excess fluid, causing the gas to compress.
When air is used as gas, this shock absorber is called hydraulic ("Soviet" shock absorbers "SAAZ"). The lack of air is that it is constantly shaking "froths oil", and with stronger shaking, low pressure bubbles may occur, which significantly reduces the effectiveness of the shock absorber.
Nitrogen is often used instead of air. Sometimes it is pumped under low pressure of several atmospheres. Such shock absorbers are called gas-filled low pressure. But low-pressure nitrogen does not solve the cardinal problem "foaming oil" and cavitation (i.e. the formation of low pressure bubbles).
The solution was found when the French engineer De Carbone pumped nitrogen into the expansion chamber at a pressure of more than 20 atmospheres and separated the nitrogen from the oil with a piston gasket that does not allow nitrogen and oil to come into contact with each other. This removed the problem of oil foaming and cavitation. The high-pressure nitrogen allows the piston valves to operate silently and quickly, and creates additional force on the stem. These shock absorbers work efficiently and accurately.
Gas-filled shock absorbers are not recommended for use on small cars, since the additional force exerted on the body by such shock absorbers is harmful to "crumbs".
Recently there have been new developments. For example, a firm "Koni" manufactures shock absorbers with stiffness adjustment. Most "heaped up" allows you to do this directly from the cabin. Such "steepness" installed on a Maserati car. In turn, the firm "BOGE" developed an automatic ride height control system (system "Nivomat"). Its meaning is that when the car is loaded, it "sags" and it changes ground clearance (clearance). As soon as the car is loaded, the vibrations of the wheels during movement actuate a pump built into the shock absorber structure. This pump already after a few hundred meters restores the necessary ground clearance. After unloading the machine, the pump automatically adjusts to the old ground clearance.
The shock absorber is that part of the car that you don’t think about until the moment it breaks. Once the shock absorber "covered himself", we realize how bad it is without him and how good it is with him.
A car with non-working shock absorbers after driving through any hillock begins to sway dangerously, you can even catch asphalt with its belly. The shock absorber can jam, then the car turns into "stool". If this happens, then the baby understands that the shock absorbers need to be changed or repaired.
But usually shock absorbers wear out gradually and the driver does not notice this. According to Western experts, in Europe, about 30% of cars older than 5 years drive with damaged shock absorbers. And what is being done in the CIS countries with our roads is generally unknown.
But shock absorbers affect not only comfort, but also traffic safety. Here it is appropriate to present the results of the work of an independent research organization "Tuv Rheinland", which conducted an examination on the impact of a shock absorber on traffic safety.
When braking at a speed of 50 km/h on a dry road with one shock absorber worn by 50%, the stopping distance of the car increases by two meters. Whether it's a lot or a little, you be the judge. But how often these two meters are not enough to avoid tragedy.
When a car with 50% worn shock absorbers drives into a puddle with a layer of water of 6 mm, the effect of hydroplaning (when the car "pops up" over the coating and becomes unmanageable) occurs at a speed of 81 km / h. With normal shock absorbers, this speed is 85 km / h. In addition to the above, "killed" Shock absorbers increase the risk of vehicle skidding in tight corners. Also, worn out shock absorbers disable many parts of the car: tires, springs, wheel suspensions, ball joints, etc.
Often, motorists think about replacing a shock absorber only when oil flows out of it: "the racks are leaking - it will be necessary to replace somehow". But this is the last stage of life (Or rather, death!) shock absorber. It is not recommended to bring the car to this state. And to check the operation of shock absorbers, it is not necessary to go to special stands. We only need "to live" every corner of the car, and if there is more than one full swing after the roll, then the shock absorbers "won't survive". They need to be replaced.
Manufacturers recommend checking the condition of the shock absorber after every 20 thousand kilometers of the car.
So, you have decided to replace the shock absorbers. But how to choose? Remember that shock absorbers largely determine the nature of the car's handling. By replacing the shock absorber, you can turn a soft suspension into a sports one. If you are at high speeds, for example, "eight", you are annoyed by excessive buildup of the body, our advice: buy shock absorbers of a sporty nature (Koni, Bistein, etc.), but be aware that the suspension may be stiff, and the road profile will be transmitted in detail to those sitting in the cabin.
"Soviet" shock absorbers, of course, are cheaper than foreign ones. And the owners "our" cars can choose. You can buy SAAZs, or you can buy products from foreign companies.
For foreign car owners, the choice lies between "relatives" shock absorbers, that is, those that are supplied directly to the conveyor of the manufacturer, and products of companies operating in the secondary market. There are shock absorbers specifically for used cars. These products are usually much cheaper "relatives", and the quality and characteristics of such products are not worse, and sometimes better than factory ones.
But replacing shock absorbers is not an easy task. There are many subtleties and tricks here. And therefore, many companies give a guarantee only with proper installation at service centers.
Now about guarantees. Normal city warranty should be 1 year, regardless of mileage. We would recommend buying shock absorbers in company stores, and not in the markets. In the markets, of course, it is cheaper, but then the racks can be changed every six months. As the saying goes, a miser pays twice.
We will give a description of the main manufacturers of shock absorbers, whose products can be purchased.
SACHS is the European leader in the supply of shock absorbers to the conveyor. Installed as standard on BMW, Audi, etc.
BOGE - manufactures hydraulic and gas shock absorbers. Supplied to BMW, Saab, Volvo.
MONROE - ranks first in Europe in the sale of shock absorbers to the secondary market. Manufactures hydraulic and gas-filled low pressure shock absorbers. Supplied by Volvo.
Gabriel is an American company. Second place in Europe in sales of products on the secondary market. Produces hydraulic and gas shock absorbers.
KAYAVA is a Japanese company. Products are supplied to many assembly lines of Japanese automakers. Shock absorbers for European-made cars are also produced.
DE CARBON is a French company that was the first to produce high pressure gas shock absorbers for Mc Ferson suspension.
BILSTEIN - sports shock absorbers. Are delivered on some German cars, for example, Mercedes-Benz.
KONI - elite Dutch shock absorbers. Supplied to Ferrari, Porsche. They are used in "Formula 1", racing Indycar. Shock absorbers of this company are also used in front-wheel drive VAZs.