Antilock Braking System

Principle of operation

The ABS was originally designed to help the driver maintain control of his vehicle, in the case of braking under conditions of precarious grip (rain, snow, ice, gravel ...). This keeps the directivity of the vehicle so, perform evasive action possible, while optimizing the braking distance, it increases significantly when the wheels lock and slide the tires on the pavement.

During emergency braking, ABS regulates the pressure in the brake system by adjusting the maximum hydraulic pressure for each wheel by means of solenoid valves: If one wheel slows down abnormally, it releases the pressure of instant brake at the wheel and this, as it does not adequately re-accelerates. The system works by releasing pulses (so that the wheels tend to re-lock when the pressure rises enough in their respective brake circuits), something you feel in general that the brake pedal will vibrate at the rate of pressure variations of the brake.

The ABS prevents the wheels from locking, the driver keeps the maximum deceleration, the braking coefficient of friction of a tire that slips around 30% against 80% in normal conditions. Similarly, the tires do not slip, they keep their directional capability.

A good braking without ABS will be more effective than the ABS (since the principle of operation of the ABS is the reduction of braking). Therefore, in sports use, the driver brakes better without ABS in the presence of this system. But, taken by surprise in a routine traffic situation (a child crossing the road behind a truck for example), the driver will carry a much less reflective and braking is likely to lock the wheels: in this case, the ABS allows a more efficient braking in the end.

Even with ABS, studies, some in a driving simulator showed that the driver in emergency situations, tends not to press hard enough on the brake pedal. So when the system detects an abnormally fast passing the gas pedal to the brake pedal, he decides to put the maximum pressure brake. And that is why we are now on many a vehicle with emergency braking. This allows for a more aggressive attack when braking, even release the pressure if the brake can be quieter (more distance than expected).

So to make a good braking, it is better to start slow and then hard to ease pressure on the brake pedal to suit the conditions, rather than vice versa (of course, heavy braking is less comfortable for passengers). By the time the driver realizes that the brake is not enough support-at least 1 second, was then transformed into a distance too great.

Finally, if in theory on dry surface, the experienced driver can be more effective than the ABS, in practice, with all the risks that driving on the road and some situations are difficult to predict, a braking system with ABS is often a efficient and safer.

The operation of the ABS is also very dependent on the quality of the damping system running gear of the vehicle. Indeed, a defective damping can no longer keep the wheels of the vehicle in optimum contact with the road, causing loss of adhesion that promotes blockages wheels event of rapid deceleration.

Marco 110;