Mercedes S-class W202

1993-2000 of release

Repair and car operation

Mercedes W202
+ 1.2. The general data
+ 2. Maintenance service
+ 3. Engines
+ 4. Greasing system
+ 5. Cooling system
+ 6. Heating, ventilation
+ 7. Ignition system
+ 8. Fuel system
+ 9. Transmission
- 10. A running gear
   + 10.1.2. Shock-absorbers
   + 10.1.3. Forward springs
   10.1.4. The stabilizer of cross-section stability
   + 10.2. The back bridge
   10.3. What for the shock-absorber is necessary
   10.4. Types of shock-absorbers
   10.5. Additional protection of spherical hinges of steering draughts
   10.6. "Artful" bolts and nuts
+ 11. A steering
+ 12. Brake system
+ 13. A body
+ 14. An electric equipment
+ 14.2. Electroschemes

10.3. What for the shock-absorber is necessary

To understand, the shock-absorber what for is necessary, – try to do a bit of travelling without it...

That the car did not perceive all roughnesses on road, in a car suspension bracket any elastic element is necessarily used. Usually применятеся a spring. Besides a spring, the spring can be used, but it is already full архаика. Other alternatives of a spring – a pneumosuspension bracket "Citroen" or гидропневмоподвеска "Rover" which work on the compressed gas. But we will return to a spring. At movement on road the car starts to be shaken, and it is inadmissible. The main task of the shock-absorber also consists in extinguishing these fluctuations, or демпфировать.

All shock-absorbers work by such principle: in the shock-absorber cylinder there is a rod with the piston, which "goes" in oil. Oil at shock-absorber work flows through a special aperture of the piston. It also creates necessary resistance to rod movement. Also in the shock-absorber there should be a capacity (компенсаторная the chamber) with the compressed gas (air or nitrogen). In the shock-absorber the piston goes and supersedes surpluses of a liquid, forcing to be compressed by gas.

When as gas air is used, this shock-absorber name hydraulic ("the Soviet" shock-absorbers "SAAZES"). A lack of air that it at constant jolting "makes foam oil", and at stronger jolting there can be vials of low pressure that considerably reduces a shock-absorber overall performance.

Instead of air nitrogen is often used. Sometimes it закачивают under low pressure in some atmospheres. Such shock-absorbers name газонаполеннными low pressure. But nitrogen under low pressure does not solve a cardinal problem of "oil foaming" and кавитации (that is formations of vials of low pressure).

The exit has been found, when the French engineer De Karbon закачал in компенсаторную the chamber nitrogen under the pressure of more than 20 atmospheres and has separated nitrogen from oil a lining-piston which does not allow nitrogen and oil to contact among themselves. It has removed a problem of foaming of oil and кавитации. Nitrogen under a high pressure allows piston valves to work silently and quickly, and also creates additional effort to a rod. Such shock-absorbers work effectively and precisely.

Gazonapolnennye shock-absorbers are not recommended to be used by small cars as the additional effort to a body, rendered by such shock-absorbers, is harmful to "crumbs".

Recently there were new workings out. For example, firm "Koni" makes shock-absorbers with rigidity adjustment. "Heap most up" allows to do it directly of salon. Such "steepness" is put on car Maserati. In turn firm "BOGE" has developed system of automatic control of a road gleam (system "Nivomat"). Its sense that when the car is loaded it "gives" and at it the road gleam (road clearance) changes. As soon as the car is loaded, fluctuations of wheels at movement put in action the pump which has been built in a design of the shock-absorber. This pump already after several hundreds metres restores a necessary road gleam. After unloading the car the pump is automatically adjusted on old size of a road gleam.

The shock-absorber is that part of the car on which you do not reflect until while it will not break. As soon as the shock-absorber "was covered", we realise, as without it it is bad and as with it it is good.

The car with idle shock-absorbers after journey of any hillock starts to be shaken dangerously, it is possible even to hook a belly on asphalt. The shock-absorber can and jam, then the car turns to "stool". If it has occurred, also to the baby it is clear – shock-absorbers should be changed or repaired.

But usually shock-absorbers wear out gradually and the driver of it does not notice. By estimations of the western experts, in Europe about 30 % of cars is more senior 5 years go with the spoilt shock-absorbers. And that becomes in the CIS countries with our roads – in general it is not known.

And after all shock-absorbers influence not only comfort, but also on traffic safety. Here pertinently to result results of work of the independent research organisation "Tuv Rheinland" which examined about influence of the shock-absorber on traffic safety.

At braking for the speeds of 50 km/h on dry road with one shock-absorber which has been worn out on 50 %, the brake way of the car increases by two metres. It is a lot of it or a little – to judge to you. But as it is frequent these two metres and does not suffice for tragedy avoidance.

When the car with the shock-absorbers worn out on 50 % drives to a pool with a sheet of water in 6 mm, effect of hydroplaning (when the car "emerges" over a covering and becomes uncontrollable) comes at speed of 81 km/h. At normal shock-absorbers this speed equals 85 km/h. Besides the aforesaid, "the killed" shock-absorbers raise risk of a pulling down of the car on abrupt turns. Also the worn out shock-absorbers put out of action many details of the car: tyres, springs, suspension brackets of wheels, spherical support etc.

Often motorists reflect on shock-absorber replacement only when from it oil will begin to flow: "racks have begun to flow – it will be necessary to replace somehow". But it already last stage of a life (is more true, already death!) the shock-absorber. To this condition to lead up the car it is not recommended. And to check up work of shock-absorbers, it is unessential to go on special stands. It is necessary only "прожать" each corner of the car and if after rolling will be more than one full wave then, shock-absorbers "will not sustain". It is necessary to replace them.

Firms-manufacturers recommend to check a condition of the shock-absorber after each 20 thousand in km of run of the car.

So, you have decided to replace shock-absorbers. But how to choose? Remember that shock-absorbers in many respects define character of controllability the car. Shock-absorber replacement it is possible to transform a soft suspension bracket into the sports. If you on high speeds, for example, on "eight", you are irritated with an excessive swing of a body, our council: buy shock-absorbers of sports character (Koni, Bistein, etc.), but know that the suspension bracket, probably, will be rigid, and the road profile will be transferred in detail sitting in salon.

"The Soviet" shock-absorbers are, of course, cheaper than the foreign. And owners of "our" cars can choose. It is possible to buy SAAZES, and it is possible to buy production of the foreign companies.

At owners of foreign cars the choice lies between "native" shock-absorbers, that is what are delivered directly on the manufacturer conveyor, and production of the firms working on the secondary market. There are shock-absorbers specially for second-hand cars. Such production usually much is cheaper "native", and quality and characteristics of such products is not worse, and sometimes and better, than factory.

But replacement of shock-absorbers not such simple business. Here it is a lot of subtleties and cunnings. And consequently many firms give a guarantee only at correct installation on the services-centres.

Now about guarantees. The normal guarantee on a city should make 1 year, irrespective of run. We would recommend to buy shock-absorbers in firm shops, instead of in the markets. In the markets is, of course, cheaper, but then also racks it is possible to change everyone half a year. As they say, avaricious pays twice.

Let's give the characteristic of the basic manufacturers of shock-absorbers, whose goods can be got.

SACHS – is the European leader on delivery of shock-absorbers to the conveyor. It is established serially on BMW, Audiи other

BOGE – makes hydraulic and gas shock-absorbers. It is delivered on BMW, Saab, Volvo.

MONROE – wins first place in Europe on realisation of shock-absorbers on the secondary market. Makes гадравлические and газонаполненные shock-absorbers of low pressure. It is delivered on Volvo.

GABRIEL – the American firm. The second place in Europe on production realisation in the secondary market. Makes гадравлические and gas shock-absorbers.

KAYAVA – the Japanese firm. Production is delivered on many conveyors of the Japanese motor-car manufacturers. Shock-absorbers for cars of the European manufacture are issued also.

DE CARBON – the French firm, the first let out gas shock-absorbers of a high pressure for suspension bracket Mc Ferson.

BILSTEIN – sports shock-absorbers. Are delivered on some German cars, for example, Mersedes-Benz.

KONI – elite Dutch shock-absorbers. Are delivered on Ferrari, Porshe. Them use in "Formule-1", races of Indikar. Shock-absorbers of this firm are used also in front-wheel VAZs.