What is meant by ABS in cars

The security gap in ABS

Contrary to popular belief, the anti-lock braking system (ABS) has less of the task of making the braking distance as short as possible, but rather of maintaining directional stability and steering ability in the event of panic braking. This is the hope that the inexperienced driver (= the vast majority) could avoid an obstacle after panic braking and thus avoid a collision.
From a technical point of view, the ABS measures the slip on the wheels. As soon as the slip becomes too great, the ABS briefly releases the brake and the wheel can roll again. The wheel (and thus the vehicle) is not braked in this short phase. Then the ABS lets the brakes grip again, but the ABS only allows a wheel to lock completely for a brief moment at most.

§41b StVZO calls these systems 'automatic blocking preventers' (ABV) and prescribes them for buses and most trucks over 3.5 t. They have also established themselves in normal cars. For a few years, Audi had a switch in the cockpit that could be used to deactivate the ABS, but an EU directive prohibits such switches.

In principle, there is no problem with ABS either, it not only maintains the ability to steer, but also shortens the braking distance - with one exception: on loose surfaces such as sand, snow and gravel, locking wheels sometimes have considerably shorter braking distances because they do Push loose ground in front of you and form a kind of wheel chock in front of the wheel - the wheel digs itself in.

Of course, you pay for the short braking distance with the loss of steering ability and in normal road traffic the ABS has certainly saved each of us from a dangerous situation, while very few could have avoided an accident with locked wheels.

It gets dangerous here

However, it becomes uncomfortable under the following circumstances: You drive up a mountain, sit down in a restaurant and eat comfortably. While you are still dining, heavy snowfall sets in. You can still look forward to the dancing snowflakes and the romantic view while eating. You drive back in heavy snowfall, but because you recently bought new M + S tires, don't worry.

But then you want to brake on a downhill gradient because you notice that gravity is making your car faster and faster. You brake, the brake pedal pumps and the ABS prevents - as expected - the wheels from locking. Unfortunately, the downhill gradient accelerates your vehicle more than the brakes controlled by the ABS can decelerate. Even though you - already in a slight panic - press the brake pedal through the floor pan, your vehicle will go even faster. You just remember the ADAC. In cases of acute brake failure, he recommends the 'sheet metal brake', i.e. you drive the body against the mountain side and the rock will ruin the sheet metal cladding of your beautiful car, so you stop.

Unfortunately, the mountain side is on the left today, but the edge of the road is pretty steep downhill and you don't dare to predict whether the guardrails in the curve that is coming your way can stop the 1.6 tons of your limousine.

"I have to go left" - when you think that, a bus is coming around the bend in front of you. It would be suicide to use the tin brake now and you don't know yet what the oncoming traffic will look like behind the curve. You feel for the card of your private supplementary insurance and hope that you will either manage the curve or the emergency doctor will quickly diagnose that you are a private patient when you are admitted to the hospital.

Then suddenly everything becomes very peaceful, you feel weightless and carefree. You see a bright light and you can still hear the voice of the seer from Steven Spielberg's' Poltergeist ', warning you'She mustn't go into the light - tell her that - not into the light'. But you don't care, everything in you strives towards the source of happiness and security ...

This dramatic portrayal is of course fictitious and perhaps a little exaggerated. But in principle it also affects off-road vehicle drivers who drive off-road and downhill on sandy ground.

What can you do about it ?

Permanently deactivating ABS would certainly be the worst option, because in most cases it is more useful to the driver than can be expected to cause damage from rare traffic situations. Right now I'm only looking at these possibilities:

  • A corresponding switch could be installed to deactivate the ABS in emergency situations. However, this invalidates the vehicle's operating license and if the braking force distribution between the front and rear axles is controlled by the ABS, the rear wheels could block in front of the front wheels, which means there is a risk of skidding.
  • If you turn the ignition key at the crucial moment, the ABS should also switch off. In addition, the brake force distribution and the power steering are probably eliminated immediately and the brake force assistance can either disappear immediately or after pumping a few times with the pedal.
  • This common tip is quite trivial: If possible, avoid such situations by planning in advance.
  • Wait for the technical progress in ABS systems.