S-class W202 Mercedes
1993-2000 of release
Repair and car operation
+ 1.2. General information
+ 2. Maintenance
+ 3. Engines
+ 4. Greasing system
+ 5. Cooling system
+ 6. Heating, ventilation
+ 7. Ignition system
+ 8. Fuel system
+ 9. Transmission
+ 10. Running gear
+ 11. Steering
- 12. Brake system
12.2. Anti-blocking system – ABS
12.3. The additional equipment – ASR system
12.4. Specifications of brake system
12.5. Overlays of forward brake shoes
+ 12.6. Overlays of back disk brakes
12.8. Forward brake disk
12.9. Back brake disk
12.10. Brake liquid
12.11. Air removal from brake system
12.12. Brake pipelines / hoses
12.13. Replacement of brake highways
12.14. Brake shoes of the parking brake
12.15. Adjustment of the parking brake
12.16. Stoplight switch
12.17. Diagnostics of malfunctions of brakes
+ 12.18. Wheels and tires
+ 13. Body
+ 14. Electric equipment
+ 14.2. Electroschemes
12.3. The additional equipment – ASR system
System of antiprobuksovochny adjustment of a drive (Antriebs-Schlupf-Regelung: ASR) is logic development of ABS system.
ABS prevents blocking of wheels when braking. Thanks to it the car when braking remains operated and does not change the direction.
The ASR system prevents pro-slipping of driving wheels at a troganiye, a set of speed and during a trip, for example, at various coupling of wheels, on turn and at sudden maneuvers with direction change. So the optimum traction effort is carried out.
ASR operates in two various planes if slips one or both wheels, the corresponding wheel are braked. Thus engine capacity automatically decreases.
Components available in ABS system are supplemented for ASR system with hydraulics, electronics and an electronic pedal of gas (Е – Gas). By pressing of an electronic pedal the butterfly valve is given by the electromotor with electronic control.
By means of four sensors the general for ABS and the ASR device measures frequency of rotation of all four wheels and processes information.
At the pro-slipping beginning in the corresponding brake pressure raises, and the wheel is automatically braked. If pressure of braking reaches the value braking a wheel. It is supported to constants. If the number of turns comes nearer to optimum, pressure decreases. Thanks to it the wheel works in an optimum range of coupling. Pritormazhivaniye of a wheel during a troganiye from a place acts as differential blocking. If the second wheel slips also, it is regulated in the same way.
At a troganiye on a wheel standing on viscous soil, the most part of the driving moment, probably also trogany can be transferred at unilaterally slippery road.
The same occurs and during a trip when revolves one or both wheels and at the expense of an automatic pritormazhivaniye course stability of the car remains.
If pro-slipping of a back wheel leads to automatic braking, and the second wheel is on pro-slipping border, the electronic system defines effort to wheels as too big and in only a few milliseconds by means of an electronic pedal gives less gas. It occurs when the driver in an extreme situation gives full gas. Thanks to electronic control the engine torque decreases, and it is transferred to both wheels without changes.
The logic of ASR such is that at wheel pro-slipping at low speeds at first a wheel is braked (adjustment of a brake contour), and on high speeds at first decreases engine capacity (adjustment of the driving moment).
At the same time the system constantly checks, whether improved, for example, quality of coupling of wheels with soil and at improvement transfers to wheels all capacity from the engine.
The indicator of work of ASR informs the driver that the system begins adjustment and that conditions of driving come nearer to the boundary.
Work of ABS system does not depend at all on ASR, both systems perfectly supplement each other.
At deep snow and application of wheel chains, and also, for example, at movement on friable sand on cross-country tires thin adjustment of pro-slipping of wheels affects negatively driving conditions. In such cases the special program of work of the control unit, chosen by the driver by means of the Schneekettenschalter switch (the switch of chains of antisliding) is provided. The increased pro-slipping of wheels that the car could "be gnawed through" in the above-stated situations is thus allowed. As such adjustment negatively affects stability of driving at high speeds, she acts only till speed of 38 km/h. At achievement of speed of 60 km/h "the logic of chains of antisliding" is disconnected. At the included mode the sign on the switch is shone.
The system of adjustment of the probuksovochny moment of the engine (MSR) is built in ASR system also. It prevents too strong zatormozhivaniye of wheels when braking by the engine and pro-slipping if, for example, on the slippery road there is a switching on lower transfer or on low transfer gas is sharply dumped. At beginning pro-slipping the brake moment of the engine at the expense of an automatic priotkryvaniye of a butterfly valve decreases. Thanks to it the car is stabilized that means effectiveness of a back drive.