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 and 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. Manufacture of low pressure hydraulic and gas-filled 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 McFerson suspension.
BILSTEIN - sports shock absorbers. Supplied on some German cars, for example, Mersedes-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 vases.
Shock absorbers according to their design are divided into two main types: double-tube and single-tube shock absorbers.
Single tube damper
1. Atmospheric pressure.
2. Valve that regulates compression resistance.
3. Tensile strength control valve.
4. Bypass valves.
Double tube shock absorber
1. Atmospheric pressure.
2. Backup camera.
3. Basic one-pipe system.
A damper is an additional mass that provides springiness and dampens the vibrations of the vehicle. The damper assimilates the oscillations of the main system, that is, the main system stops vibrating - the movement is limited by the vibration damper. Dampers minimize body movements. Can be used as a damper element; like a liquid (oil shock absorbers), and gas (gas shock absorbers).
A single-tube shock absorber is characterized by a high degree of reliability, low sensitivity to overloads, non-criticality to the installation position. The disadvantages include the dependence of the degree of quenching on the compression parameters (which in recent developments is compensated by installing additional bypass valves in the piston) and that the monotube damper is a long type damper.
The twin tube shock absorber is technologically known as the atmospheric, low pressure double tube type.
Advantages: insensitive to external damage. Here, in contrast to a single-tube shock absorber, mechanical influences can also be received by the outer tube, the adjusted position of the machine is limited by the area of the body structure. This is a short type of shock absorber because the balance chamber is located behind the working cylinder.
Disadvantages: the shock absorber is sensitive to overload (damping stops). Only certain installation positions are possible, precision matching of pipe diameters.
The damping characteristics are the result of the sum function of the orifice damping and the spring-loaded valve that closes the passage; the spring responds to pressure by increasing the free aperture of the exit port. The piston bore and spring can be specially adapted to ensure the damping function is linear and soft. An internal adjustment mechanism is used to obtain several performance characteristics for an individual damper. Compression ratio values are often only 30...50% of the recoil capacity.
Shock absorbers with electronically adjustable characteristic (active refinement) are used to extend the range of driving comfort and increase safety. Controlling the damping parameters, on the other hand, results in a link between comfort and safety.