How to brake properly on ice with abs?

Training at a driving school is enough to put a new driver on the roads. At the same time, during the training course, the future motorist will learn practically nothing directly about driving a car, learning the rules and performing exercises on the training ground. Finding yourself on real roads and purchasing your first car, the driver may be faced with the problem of the absence or presence of an anti-lock brake system. It is important to be able to correctly stop a car at high speed that is equipped with an ABS system or that does not have it.

A little about the device

I have already written a whole article about the ABS system - read it, it will be interesting. But today I want to remind you a little about the operating principle of this device.

WITHOUT ABS

A car that does not have such a system, on a slippery road (be it snow or rain), when you press the brake pedal, locks all 4 wheels, especially if emergency braking. Thus, the braking distance increases, because the contact patch between the rubber and the coating is the same - on an icy (snowy) road it will quickly become clogged with snow, but on an asphalt road (rain) it will float.

The trajectory will not be linear and, most likely, a skid will appear. Many professional drivers deliberately let the car go into a slight skid, then the pedal is released and pressed again - a kind of imitation of the operation of the anti-lock braking system.

With ABS

There are special devices installed in the wheel of a car: a gear, as well as a sensor that detects wheel locking. After this, the signal is sent to a special controller, where a decision is made to unlock one side or another.

Thus, the wheels are not completely blocked, and braking occurs more efficiently (roughly, the braking distance can be described as - dot - dash - dash - dot). Thus, the surface of the tire always substitutes a new part of the wheel, then another part is changed for braking, etc. All this happens automatically.

I think this is understandable. Now the lesson itself.

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ABS and classical mechanics?

When driving, the car's wheels are constantly in contact with the road surface with part of their area, which is called the contact patch. Thus, the wheels (and therefore the entire car) are constantly affected by the static friction force while it is moving. Since it is greater than the sliding friction force, it prevents the wheel from slipping. Therefore, it is logical to use the static friction force, and not the sliding friction force, to stop the car.

What happens when we press the brake pedal? The driving wheels of the car are blocked and stop rotating, and the sliding friction force begins to act on them, which, although less than the above-mentioned static friction force, is quite sufficient on roads with good, dry surfaces. Well, what if it rained, or there were frosts at night, or under the wheels of your car there is not asphalt, but a muddy primer? If you press the pedal sharply, you can easily send your car into a skid. It is to prevent this situation that the ABS system exists.

ABS is installed on most manufactured cars

Emergency Braking Basics

Used in case of emergency. It is clear that we are talking about sharply pressing the brake pedal. But even such a seemingly simple action has a number of unshakable rules. Everyone who has a driver's license needs to know them. These are the rules that will teach you how to brake properly in a car:

When pressing the brake suddenly or for a long time, do not turn the steering wheel too much. This may cause the vehicle to skid and roll over.
Don't bend your whole body forward. Try to keep your shoulders and shoulder blades touching the back of the chair. This way you will better feel the change in the car’s position relative to the road and protect yourself in the event of a possible collision.
During emergency braking on a car with a manual transmission, you cannot depress the clutch. The car will slow down further by reducing engine speed.

Be careful on the slippery road.

Should I depress the clutch pedal?

When braking without ABS, the risk of stopping the engine does not arise before stopping, as with ABS, but at the very beginning of braking. After all, blocked - stopped wheels connected to the engine by a transmission stop it... Especially on a slippery road, when braking “to the floor” in a gear, the engine stalls instantly. And subsequent acceleration attempts may fail. In addition, when the engine is turned off, the power brakes and steering are disabled, which makes it difficult to control the car.

Therefore, during emergency skidding braking, depress the clutch pedal immediately - at the beginning of braking .

Using ABS during hard braking

In a standard situation, the anti-lock braking system has virtually no effect on the braking distance - it remains the same as on cars without ABS. The advantage is that the car does not lose control and does not skid. Provided that the skidding is caused precisely by braking, and not by an incorrectly selected speed limit and a sharp turn of the steering wheel. What to do if you need to apply emergency braking? How to brake correctly with ABS in case of danger of an emergency?

On auto courses, you were probably warned against pressing the brake pedal to the floor, since this is what leads to skidding. On cars with ABS, it is better to forget about this rule. As soon as you feel the need to brake sharply, immediately press the brake and clutch pedals all the way. Yes, don’t forget about the clutch, because it is necessary to completely exclude the engine from the braking process.

Sharp braking with and without ABS

Don't try to use brake pulsations - ABS will do it for you and better than you. Your task is to press two pedals to the floor as sharply as possible and not release them until they come to a complete stop. At the same time, all the time you are braking, you will hear a terrible grinding noise - the result of the ABS system - take it for granted.

If you need to stop suddenly, even on difficult icy road surfaces, then you need to do this as quickly as possible so that the anti-lock braking system works instantly and you do not lose control of the car. When braking, try to steer yourself, keeping the car on a slippery road and avoiding collisions. After all, this is the main advantage of the ABS system - it leaves you the ability to control the car.

Braking

To stop a car equipped with ABS, you simply need to hold down the brake pedal. The system itself will distribute the required pressure across all 4 wheels.
In car models equipped with a manual transmission, to slow down, you must simultaneously press the brake pedal and clutch to exclude the engine from braking. Deceleration with the participation of the motor is carried out by reducing the speed transmission of the drive wheel.
When ABS operates, a “crunch” of the system is heard, and the driver’s foot feels a twitching of the brake pedal.
When using the anti-lock braking system, remember that it stops working at speeds below 5 km/h.
You need to understand that braking on turns using anti-lock is not only ineffective, but also unsafe. The system will not be able to cope with the redistribution of this level of load between the wheels, and the car may skid or roll over.

When braking using ABS on uneven and non-uniform surfaces, its efficiency coefficient is significantly reduced. This manifests itself in a strong increase in braking distance.

When is ABS useless?

It is important not only to know how to brake correctly with ABS, but also to be able to identify situations when you cannot rely on the system, and therefore you can only rely on your own strengths and skills.

Video testing a car with and without ABS:

On rough roads, ABS is more likely to become a hindrance, since it starts to work with some delay. The brake pads are released at the moment when the wheel is on the “approach”, respectively, when it lands, it moves for some time before the next ABS braking impulse begins to act on it again.

Approximately the same thing happens on roads with mixed surfaces, for example, on partially icy or snowy roads, where sections of dry and wet asphalt, snow and ice alternate. The ABS system simply does not have time to react in a timely manner to changing conditions, so it is better to maintain a distance and speed limit.

On loose surfaces (sand, gravel), a car with an anti-lock braking system brakes worse than without it. The point here is that the main role in braking is played by the shaft in front of it, which is heated by the locked wheel. In the case of ABS, this does not happen and the braking distance is significantly longer.

Also, anti-lock does not work at low speeds, usually below 7-10 km, so you should be careful on slippery slopes. In general, as experienced car owners say, it is best to avoid triggering the ABS - it’s the most reliable way!

How does ABS work?

A modern ABS system is a complex electrical “organism” consisting of three main elements:

speed sensors installed on the hub of each wheel of the car;
pressure valves that distribute it along the brake system line individually to each wheel;
a control unit that receives signals from speed sensors and, after processing the information, distributes pressure (braking force) to each wheel.

The necessary condition for the activation of the ABS system is that the brake pedal is pressed and at least one wheel is locked. As soon as the speed sensor (one or more) gives a signal that the wheel has stopped rotating and the sliding friction force has begun to act on it, it eliminates the braking force, allowing the wheel to rotate, but at a lower speed, since the first braking impulse has time to extinguish a little speed.

Components of the anti-lock braking system

As soon as the braking force stops acting on the wheel, it begins to rotate at a certain speed, which is again read by the sensor on the wheel hub, transmitting data to the control unit. He, in turn, having analyzed it using a complex algorithm and finding it not low enough, transmits the next braking impulse to the wheel, but at the same time selects the force in such a way that the braking is carried out on the verge of blocking - that is, the wheel does not stop completely.

The powerful processor of the anti-lock braking system manages to read data from all the wheels of the car and, analyzing it, sends short-term brake impulses, trying to slow down the speed of rotation of the wheels without completely and permanently blocking them. Essentially, ABS is a pulse braking system. Experienced Formula 1 or NASCAR racers brake in much the same way, pressing the brake pedal repeatedly so as not to deprive the car of controllability. True, even very experienced riders manage to press the pedal no more than 3-4 times per second, while ABS does this 10-15 times.

Basics of sliding safely on ice and wet roads

Although many cars are now equipped with ABS, the principles of safe stopping in a car have not changed much.

Some of our experienced motorists, accustomed to the driving style of domestic classic cars, deliberately disable ABS. For beginners, this approach is categorically not acceptable.

There are several basic ways to properly brake a car in icy conditions and on wet asphalt. Let's look at each of them. Gearbox and engine Slowdown occurs by reducing engine power and switching the gearbox to a lower level. Due to this, the wheels receive fewer revolutions and cannot rotate at a higher speed.

There is some difference between engine braking with automatic transmission and manual transmission. When slowing down in a car with a manual transmission, the driver switches gears, and with an automatic transmission, the electronics are responsible for this.

Depending on the car model, the gear shift speed of an automatic transmission may be different. Therefore, if your car has the ability to operate the box in several modes, then when braking using the engine you need to use manual.

Manual gear shift lever.

To learn how to brake using the engine and transmission, do the following:

Reduce the speed with the accelerator pedal.
Depress the clutch (for manual transmission or manual automatic transmission).
We set the position of the box handle to the next lowest level.
Release the clutch and press the gas with your right foot.

If necessary, this pattern of actions is repeated several times until switching to the lowest gear. This kind of braking is acceptable for slowing down a car on a straight section of a slippery road and when going downhill.

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Engine braking

Emergency braking and activation of ABS is an unpleasant situation in itself, which is better not to lead to. To reduce the risk of ABS chattering in winter, slow down the car in advance using engine braking.

Engine braking is an effective counter-emergency technique, relevant on long descents and slippery sections of the road. By selecting a lower gear in the transmission and thus increasing engine speed, the driver physically (by the gear ratio) limits the speed to which the car can accelerate. This dramatically reduces the risk of skidding - the car drives more stable and safer.

Engine braking is available on any transmission: mechanical, classic automatic transmission, CVT - just move the selector one or two steps lower. Even hybrids have effective engine braking, especially in forced battery charging mode. Use this technique on dangerous sections of the road.

Intermittent deceleration method

With this method, the steering wheel and foot brake are activated. The pedal is pressed in sharp jerks. Because of this, the car's wheels do not have time to completely stop. It is important to understand that this method requires some driving experience.

Apply the brakes just before the wheels completely lock. This way they don’t have time to completely stall and skid. Steer should be done when the brake pedal is depressed.

Due to alternating sharp pressure and release of the brake pedal, the pads do not have time to completely stop the wheels, and the tires do not have time to slide along the road surface. This is how the speed of the car is reduced in steps.

To understand how to properly brake intermittently on a car, you should study the procedure for this method:

Release the accelerator.
Press the brake pedal sharply.
Hold in the pressed position for a few seconds.
Then let go.

It is very important to press and release sharply. You should also try to adhere to a certain frequency of movement, at which the tires will not have time to skid.

With any method, braking efficiency depends not only on the level of professional skills of the driver. The correct selection of seasonal tires plays an important role in this.

All seasonal tire models are suitable only for summer and the spring-autumn off-season. In winter conditions, you should give preference to studded or friction (non-studded) tire models. Their tread pattern is better suited for braking on ice.

Step braking

Staged braking is in many ways similar to intermittent braking. The driver also resets the accelerator and periodically applies the brake. But unlike the intermittent one, with the stepped one, the left foot does not completely release the pedal, but keeps it slightly pressed, alternating this action with a sharp press of the brake. Thus, there is an alternation of degrees of “squeezing” of the wheel drum by the shoe (block). This method of braking a car largely copies the principle of ABS.

With the ABS system, the car remains controlled when braking.

LESSON

1) First of all, guys, you need to understand that miracles don’t happen and ABS can’t always save you. For example, in winter on an icy road with extreme braking there is not 100% protection. YES, the thorns won’t save you either. Therefore, the first rule in extreme conditions (snow, rain) is to keep an increased distance (see this lesson, everything is in detail there).

2) In such situations, I do not recommend accelerating to maximum speeds; again, this system may not save you. I repeat - miracles do not happen.

3) For those who are switching from conventional cars to variants with ABS. It just so happens that we are used to stopping the car either by coasting (we easily block the wheels - release them - block them again, etc., without causing the car to skid), or by speeding up and lowering the gear (I’m talking about winter driving). Guys, this will not work here - blocking is excluded here, because ABS will not allow you to block the wheels, the pedal will begin to resist pressing, making specific sounds. YES, and if you have an automatic, then you won’t slow down either.

4) The mistake of beginners and those who have just “moved” lies in the fact that when there is resistance to pressing the pedal, they immediately stop pressing it. Thus, only aggravating my situation, because the car did not stop. DO NOT DO THIS IN ANY CASE - IT IS IMPOSSIBLE . You need to press the pedal as hard as you can until the car stops. And the characteristic sound and resistance of the pedal should not scare you; this is how ABS works, it prevents you from locking the wheels.

5) If applied to an automatic machine, then the operating principle is as follows: we drive with our right foot on the gas pedal

– if emergency braking is necessary, simply take your foot off the gas and press the brake as hard as you can

– after the car stands up, simply remove your foot from the brake. That's it, you don't need to do anything else.

Now there is a video version of the lesson. There I tried to tell everything as simply as possible.

VIDEO

That's all guys, it's so easy and simple to brake with the ABS system. However, rely on the system - and don’t make a mistake yourself. There is no need to drive too much in bad conditions, because even the most advanced device will not be able to save you at high speeds. That's all, read our AUTOBLOG.