Mercedes of the S-class W202

1993-2000 of release

Repair and operation of the car

System of antiprobuksovochny adjustment of the drive (Antriebs-Schlupf-Regelung: ASR) is logical development of the 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 start-off, a set of speed and during a trip, for example, at various coupling of wheels, on turn and at sudden maneuvers with change of the direction. The optimum traction effort is so carried out.

ASR works in two various planes if slips one or both wheels, the corresponding wheel is braked. At the same time engine capacity automatically decreases.

The components which are available in the ABS system are supplemented for the ASR system with hydraulics, electronics and the electronic accelerator pedal (Е – Gas). When pressing an electronic pedal the butterfly valve is given by an electric motor with electronic control.

By means of four sensors the general for the ABS and ASR device measures the frequency of rotation of all four wheels and processes information.

At the beginning of pro-slipping in the corresponding brake pressure increases, and the wheel is automatically braked. If pressure of braking reaches the value braking a wheel. It is supported to constants. If speed comes nearer to optimum, then pressure decreases. Thanks to it the wheel works in the optimum range of coupling. Wheel snubbing during start-off from the place works as blocking of differential. If also the second wheel slips, it is regulated in the same way.

At start-off the most part of the driving moment can be transferred to the wheel standing on viscous soil, also start-off at unilaterally slippery road is possible.

The same occurs also during a trip when revolves one or both wheels and at the expense of automatic snubbing 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 torque of the engine decreases, and it is given to both wheels without changes.

The logic of ASR such is that at pro-slipping of a wheel at low speeds at first the wheel is braked (adjustment of a brake contour), and at high speeds at first decreases the 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 power from the engine.

The indicator of work of ASR informs the driver that the system begins adjustment and that conditions of driving approach boundary.

Work of the ABS system does not depend on ASR at all, both systems perfectly supplement each other.

At deep snow and application of wheel chains, and also, for example, at the movement on friable sand on cross-country tires thin adjustment of pro-slipping of wheels affects negatively driving conditions. 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 in such cases. At the same time the increased pro-slipping of wheels that the car could "be gnawed through" in the above-stated situations is allowed. As such adjustment has an adverse effect on stability of driving at high speeds, she acts only to the speed of 38 km/h. At achievement of the speed of 60 km/h of "the logician of chains of antisliding" it is disconnected. At the included mode the sign on the switch shines.

Also the system of adjustment of the probuksovochny moment of the engine (MSR) is built in the ASR system. 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 to lower transfer or on low transfer gas is sharply dumped. At the 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 the back drive.