It is an indispensable item for everyday driving. But what happens when you try to stop the car in winter snow covered road? Can it help you in this case ABS system? Actually yes and no. How the car stops in the snow will determine how you press the brake pedal.
We offer you a video and an explanation of how to properly stop a car equipped with ABS.
The main secret proper braking on snow, it is not to press the brake pedal sharply. That is, if you gently and smoothly press the brake pedal, then a car equipped with an ABS system will stop much faster. Otherwise, if you hold the brake pedal too hard, your braking distances there will be more on snow, even if the ABS system prevents the wheels from locking up.
Here is an example for you small video, which shows us that if you press the brake pedal incorrectly in a car equipped with an anti-lock braking system, then the braking distance will be loose snow will be very large. Also, the video shows us the difference in braking distance in the case of pressing the brake pedal more gently and smoothly.
Why is this happening? Why does the same vehicle with ABS behave differently on the road due to different braking techniques? After all, during braking on a slippery and snowy road, the ABS system should intervene, which should prevent the wheels from locking.
Here's an explanation why drivers need to depress the brake pedal more gently and smoothly when stopping in the snow. To do this, we need to understand how the ABS system works..
The basic idea behind an anti-lock braking system (ABS) boils down to the difference between kinetic friction and static friction. Imagine you're trying to move heavy box on the floor. First you start to put pressure on her with your body. To move the box from its place, you will need to make a lot of effort. And finally, after spending a lot of effort, you will move the box from its place, and it will slowly begin to move.
This is due to the difference in static friction ( static friction- friction between two objects that are not moving relative to each other) and kinetic friction ( sliding friction).
Here is the basic formula for the force of friction:
F = μN ,
Where "N" - this is a normal force (as a rule, any force that presses an object to the ground - downforce etc.), but "μ " is the coefficient of friction.
Static friction coefficients are greater than kinetic friction coefficients. When you press the brake pedal in your car, you want your car to decelerate primarily through static friction (also called rolling friction) rather than kinetic friction (sliding friction).
You understand that if the car stops due to kinetic friction, then the car can skid.
And due to static friction during correct technique braking by increasing the friction force, the stopping distance of the car may be significantly reduced. Especially on a snowy road.
Standard ABS system
The standard anti-lock braking system uses four speed sensors that are mounted on each wheel, hydraulic pump, four hydraulic valves (provided that your car uses a 4-channel ABS system) and an electronic controller (ABS control unit).
The ABS control unit monitors the rotational speed of each wheel using wheel speed sensors, the principle of which is based on the Hall effect.
If the ABS controller sees that the wheel is decelerating at a rate that does not match the rate of deceleration of the entire vehicle (does not match the speed of rotation and deceleration of other wheels), then it sets in motion hydraulic valve in the brake line (system) of this wheel. This reduces pressure in brake system distributed for this too fast decelerating wheel.
As a result, this wheel begins to turn faster and gradually its speed is compared with the rest of the wheels. The ABS system then uses the hydraulic pump in the brake system to repressurize the wheel so that it can again evenly distribute the braking force between the 4 wheels to continue stopping the vehicle.
When the ABS electronic controller sees excessive wheel braking again, it activates the valve again. This cycle repeats approximately 15 times per second.
Thanks to this control over the pressure in the brake system of each wheel (rapid injection or release of braking forces), the wheels of the car do not block, which helps to maintain traction and prevents skidding.
The only thing is that ideally it only works on asphalt. But not in the snow. Unfortunately, on snow covered surface road to press the brake pedal to the floor and wait for the car to stop is not enough.
In order to reduce the stopping distance on snow on a vehicle with ABS, you will need to apply a softer (and smoother) brake pedal.
The formula here is simple. The softer you press the brake pedal, the less likely it is that the car will stop using kinetic friction (slip). Accordingly, the less slip of the car's wheels, the more efficiently it will stop on a snowy road due to static friction. This means that the braking distance will be significantly less.
During hard braking slippery road may have problems. Anti-lock braking system (ABS) takes over this action and saves your nerves. In fact, on a slippery road, even professional driver can't brake as fast without ABS as the average driver with it. In this article we will look at anti-lock braking systems - why do we need them, how they are arranged, how they work, what they are, and what problems can arise when using them?
Location of anti-lock braking system components.
ABS pump and valves
ABS system
In theory, anti-lock system set up quite simply. If you are skidding on ice, you will see the wheels spin, but there is no traction. This is due to slippage of the bearing area of the wheel on the ice. The anti-lock braking system prevents the wheels from locking up and spinning, which gives you two benefits: stopping is faster and you keep control of the car during the stop. ABS includes the following components:- Speed sensors
- Pump
- valves
- Control block
Speed sensors
The anti-lock braking system needs to track the moment that is borderline with the wheel lock. Speed sensors mounted on each wheel, or in some cases, on the differential, read this information.valves
The braking system has valves for each brake controlled by the ABS. In some systems, the valve has 3 positions:- In position 1 the valve is open; pressure from the master cylinder is transferred to the brake.
- In position 2, the valve blocks the line, isolating the brake from the master cylinder. This prevents pressure build-up when the brake pedal is pressed harder.
- In position 3, the valve slightly reduces the pressure in the brake.
Pump
Because the valve can weaken the pressure of the brakes, it is necessary to somehow force it to its original position. For this, a pump is used; when the valve depressurizes the line, the pump pressurizes it to the required level.Control block
The control unit is a computer. It monitors speed sensors and controls valves.ABS operation
Exist various options algorithms and their combinations for ABS control. We will consider the principle of operation of the most simple system. The control unit continuously reads the readings of the speed sensors. It monitors for any slowdowns that are not normal. For example, before a wheel locks up, its speed drops sharply. If this is ignored, the wheel stops much faster than the car. Under ideal conditions, it takes the car approximately 5 seconds to stop at a speed of 100 km/h, but the wheel locks up in less than 1 second. The ABS control unit knows that such a sudden interruption of movement is not possible, so it reduces the pressure on the brakes until acceleration begins, then again increases the pressure until repeated braking. This happens so fast that the wheel does not have time to change speed sharply. As a result, the wheels are braked at the same speed as the car, while the wheels are braked in a position bordering on blocking. In this case, the system achieves maximum braking force. When the ABS is activated, you will feel the pulsation of the brake pedal; this is due to the rapid opening and closing of the valves. Some ABSs have up to 15 valve open/close cycles per second.Types of anti-lock systems
Used in cars Various types anti-lock braking systems, depending on the type of brakes installed. We will consider ABS by the number of channels - i.e. the number of valves that are controlled individually - and the number of speed sensors.Four-channel ABS with four sensors
This type is the best. Speed sensors are installed on each wheel, and a separate valve is installed for each wheel. With this type of ABS, the control unit controls each wheel individually to provide the highest braking force.Three-channel ABS with three sensors
Usually this type is used on small trucks (pickup trucks) when ABS action on all four wheels. The front wheels have two sensors and valves, one for each wheel, and one sensor and valve for the rear wheels. The rear wheel speed sensor is located on rear axle. Such a system provides individual control for each front wheel, providing maximum braking force. The rear wheels are tracked in pairs, i.e. both rear wheels must be locked for the ABS to work. Such ABS type allows the blocking of one rear wheel during braking, which reduces its effectiveness.Single channel ABS with one sensor
This type is usually installed on small trucks (pickup trucks) with ABS acting only on rear wheels. Such an ABS has only one valve to control both rear wheels and one sensor located on the rear axle. This type works in the same way as rear end three-channel ABS. The rear wheels are tracked as a pair, i.e. both rear wheels must be locked for the ABS to work. This type of ABS allows one rear wheel to lock up when braking, which reduces its effectiveness. This ABS is easy to recognize. She usually has one brake line going to both rear wheels through a tee. You can also find the speed sensor on the electrical connection next to the rear axle differential.Frequently Asked Questions about ABS
Do I need to brake intermittently on a slippery road?
When driving a car equipped with ABS, it is not necessary to brake by intermittent depressing the pedal. Intermittent brake application is used when braking a non-ABS vehicle to prevent wheel lockup and maintain vehicle control. In cars with ABS, the wheels never lock up, so intermittent pedaling will only prolong the stopping time. At emergency braking on a vehicle with ABS, firmly depress the brake pedal and hold it down while the ABS brakes. You may feel a strong pulsation in the pedal, but that's how it should be, don't let go of the pedal.Does the anti-lock braking system really work?
ABS makes braking more efficient. It prevents the wheels from locking up and provides the shortest braking distance on slippery roads. But does ABS help prevent accidents? American Institute road safety conducted a series of studies to determine how often ABS cars involved in road accidents fatal. The results of a 1996 study showed that ABS does not prevent fatal crashes. It has also been noted that vehicles with ABS are less likely to be involved in fatal crashes for the driver and passengers of the vehicle with which the collision occurred, but more fatal for the driver and passengers of the vehicle with ABS, especially in single-vehicle crashes. For this reason, there is still debate about the effectiveness of ABS. Some people think that drivers of vehicles with ABS brake incorrectly and release the pedal when they feel it pulsing. Some believe that if ABS allows you to drive a car during emergency braking, then many in a fit of panic drive off the road and crash. Recent studies show that vehicles equipped with ABS are less likely to be involved in accidents, but this is not yet a reason to believe that ABS improves driving safety.ABS Component Layout
Components of the anti-lock braking system.Let's put all the parts of ABS together and see how it works. The figure shows both an example and a close-up of the location of the ABS components in the car.
Many have heard that in a skid on rear wheel drive gas must be dropped, and on the front - add. And also turn the steering wheel in the direction of skidding and never slow down. But these "commandments" were relevant 15 years ago, and now they can be simply dangerous.
As the saying goes, the military is always preparing for last war. Most of the authors of "valuable" advice on driving a car are busy with exactly the same thing. Books become obsolete, and revisions in reprints fail to reflect the essence of the changes that have taken place.
A few words about modern electronic assistants
Over the past ten years, there are almost no cars left on the roads without ABS, and four-wheel drive on most machines became automatically connected with electronic control. ESP today is increasingly included in basic equipment, and the automatic transmission is gradually replacing the "mechanics". Yes and active systems steering is slowly penetrating into our lives - one Infiniti Q50 without a mechanical connection between the steering wheel and wheels is worth something ...
Against the backdrop of these changes, advice like "Squeeze the clutch and turn the steering wheel in the direction of skidding" does not even look like an anachronism - they are simply not applicable in practice. What about guru advice? sports driving, then again, they are only true for prepared machines, without "smart" electronics, with powerful motors and "correct" steering.
Some of the tips of the "experienced" have long lost their relevance and are close to becoming dangerous. The most massive option that appeared on the machines was the anti-lock braking system - ABS. The essence of its work is to prevent the blocking of the rotation of the wheels, and thereby the braking distance on hard surfaces is reduced and controllability is maintained during braking.
In Europe and the USA, cars without it have not been produced for a long time, in principle, we still legally allow the sale of cars without this system, but in fact almost all new cars are equipped with it. Many perceive it as an annoying hindrance and sincerely believe that without it they would have stopped earlier, and it would have been more convenient to drive the car. But in reality, a car with disabled ABS is actually an uncontrollable car.
Since the late 90s, ABS has taken over the functions of a brake force distributor - a system that prevents the rear axle wheels from locking earlier than on the front axle, and thereby maintains the stability of the car when braking. Even without her experienced driver runs the risk of completely losing when braking exchange rate stability and go sideways into a ditch. And the anti-lock braking system takes care of maintaining the stability of the car when braking on uneven surfaces, for example, when one wheel is on the side of the road and the other on asphalt. The system simply releases the brakes on the right and left wheels differently and the car ends up going straight. Previously, this problem was solved only by adjusting the suspensions, but not very effectively.
Someone, of course, really manages to cope with braking without ABS better than with it. On loose surfaces, anti-lock braking systems may indeed be less effective than locked-wheel braking or special deceleration techniques, but not always the driver can use this advantage and at least leave the car on the desired trajectory.
In addition, electronics can regulate the braking force on each of the wheels individually, and I have not yet seen cars with four brake pedals. Unfortunately, there are examples bad work systems. Everyone has heard about errors in the firmware of ABS units on cars Volkswagen group, which were revealed by the journalists of "Autoreview" during the tests Volkswagen Tiguan and several other VW and Skoda models. The system was overzealous in releasing the wheels on uneven surfaces and when braking in corners, causing the car to decelerate much less efficiently than other vehicles with ABS.
Moreover, manufacturers did not in all cases release updated block firmware, and not one of the machine models was recalled for forced replacement. But some new systems recognize loose coatings and change the algorithm of work to minimize the braking distance. You can talk about the pros and cons of the system for a long time, but now the story is about what control methods have changed with the advent of electronics in the brake drive.
Braking is allowed, but be careful
One of the few tips that everyone remembers: "Don't brake in corners." On cars without ABS, the advice is absolutely correct. Racing driving schools, in general, are in solidarity with the instructors of initial training on this issue, but they provide training in special braking techniques that still allow you to slow down on an arc.
And almost all drivers act correctly and in a racing way, trying to complete the braking before the turn. But in a critical situation, when the speed is too high, an obstacle suddenly arises or something else, they also do not slow down, although with ABS they could safely use the brakes, thereby preventing an accident or reducing the severity of the consequences.
After all, often the front wheels have a margin of traction and you can both brake and turn at the same time, and without the risk of a complete loss of control. If you have a "fresh" car with ABS - slow down, there will be nothing to worry about. The car will slow down, and slower speed is better grip, and more time for control actions.
And here's the advice emergency just slow down to the floor” they already give traffic rules, there are no “go around” there. And most of the drivers honestly slow down, not trying to go around the obstacle. Here everything is a little less clear. When taxiing, the braking distance inevitably increases, at least a little. And due to errors in the operation of the anti-lock braking system, which have already been mentioned above, the braking distance can almost double.
And if the accident could not be avoided, the good traffic police inspector will be sure that if you just slowed down without any tricks, then it would have worked, and if you were driving, then you are to blame ... But if the chances of avoiding an obstacle are high, and the consequences of a collision can be heavy anyway, it's best to try. But in order to choose the right solution, it is better to test your car in advance on braking when “rearranging” or look for tests on the Web. And then suddenly in your car there is a “wrong” firmware that will not let you slow down in principle ...
What to do with a rhythmic skid?
Another dangerous situation is rhythmic skid. He is especially unpleasant front wheel drive car. To stabilize the trajectory, when the rear wheels broke into a skid, as we all know, you need to add traction. But it is not always possible to straighten the skid, and if you “twist” the steering wheel at the same time, be late with the correction, then the skid becomes rhythmic. The backside chatters first in one direction, then in the other, the amplitude grows ... The consequences of the car leaving the track here will be harder than if the driver just let everything take its course from the very beginning.
It is often important to keep the car under control and not get into oncoming lane under a moving truck. Unfortunately, the emergency response training of most of the drivers is at a very low level, and their actions in such a situation resemble the well-known anecdote about Caruso, which Rabinovich sang on the phone.
It seems like you need to turn the steering wheel in the direction of skidding and add traction, but here is the speed of taxiing and the relevance of control actions - none. And, of course, almost everyone is sure that you can’t press the brakes and the car will immediately go into uncontrolled rotation.
In this dangerous situation it is worth remembering that electronic assistants perform better than most drivers. Yes, yes, a person cannot squeeze out five tons to replace seat belts, and press four brake pedals ten times per second to replace the ABS and ESP systems - you just have to put up with it.
The whole mighty human intellect (in its existence, however, there are also doubts when you watch videos about an accident) clearly loses in the simplest motor skills to simple electronics and pyrotechnics. Without electronics, when braking, the wheels will lock up, and the car will actually rotate, not reacting to the rotation of the steering wheel, but often this is also not the worst development of the situation - the speed will, after all, fall.
But if there is ABS, then the situation changes dramatically to the opposite. Even angular velocity machine is large enough, when the system is triggered, it will try to prevent the machine from turning around. All algorithms of the system are “sharpened” for maintaining stability during braking. And, of course, the car will slow down, so even if you fail to stay on the road, the consequences will not be so severe.
And the controllability of the car in such conditions is completely preserved - you can operate the steering wheel just as effectively. Of course, the rear axle is unloaded, but the difference in grip weight front and rear axles perfectly leveled by controlling the speed of rotation of the right and left front wheels.
I do not urge you to press the brake pedal all the way at the slightest sign of a skid - nevertheless, steering and traction work perfectly helps to straighten the skid, and experience will not be superfluous. But if there is a buildup, then it would be better to forget about the advice of the grandfather-instructor and try to take advantage of the chance that technical progress gives.
Remember: in any doubtful ABS situations not only must it prevent the wheels from locking up, it simply must keep the car in a straight line. It will perform this function not only if the car was moving straight, but will also try to straighten the trajectory in the event of a skid, equalizing the wheel speeds. And if the system has a steering position sensor, which is true for modern systems, then try the brakes to help the steering
What is the result?
Let's make a short conclusion: on modern cars with ABS, it is possible to slow down in a turn and in a skid. But only if the traditional ways out of emergency situations do not help.
The further, the more the paths of sports driving schools without "assistants" and the ways of driving modern cars will diverge. And only a complete understanding of the processes occurring with the machine, the operation of its components and assemblies and practice will provide you with real new level safety on the road. Read modern publications and do not rely on the opinion of old authorities in such responsible matters. And stay with us.
And besides, take the time and go to a large empty snow-covered area to "understand" your car. No instructors needed. Feel free to accelerate through the snow, brake to the floor, turn the steering wheel ... Do everything to understand the car at the level of reflexes. After all, there will be no time for reflection in an emergency.
With the onset of winter, the tension on the roads increases significantly, since it is no longer possible to drive on a snowy and sometimes icy road in the "summer" mode, and not every car owner can quickly change the driving style. Due to the lack of a permanent good grip wheels with pavement, braking, especially in emergency situations may result in loss of control vehicle. Therefore, with the onset of cold weather, you should at least change your aggressive driving style to a calmer one.
Experienced car owners with many years of experience, this is exactly what they do, while beginners learn from their mistakes. In order to feel more confident on a slippery and icy road, constant practice is necessary, since all theoretical advice taken together will not allow you to gain the required experience, feel the car, intuitively feel the approaching danger. It should be understood, however, that despite the modern cars a variety of systems that help in managing, for example, ABS, you should not blindly rely on them.
ABS - help or hindrance on ice
Equipping cars with driving assistance systems has led to the fact that many, especially inexperienced drivers, began to trust her too much, forgetting many moments safe driving. It should not be forgotten that with the onset of frost, you should replace the rubber with studded options- this significantly reduces the brake let on slippery roads. In order to know how to properly brake with ABS, you should get acquainted with the principle of operation of this system, which is designed to prevent the wheels from locking during braking and loss of control over the vehicle.
When trying to brake hard standard car without ABS, the wheels simply lock up, resulting in sharp decline controllability and skidding of the vehicle. It is worth noting that between the blocked tire and the road surface, the friction force will be quite weak, so it is almost impossible to quickly stop the car on a slippery road. Braking that is carried out without blocking is more efficient than sliding on an icy road surface. In addition, it prevents uncontrolled slipping and skidding of the car. The pros and cons of ABS are described in detail in the video:
To know how to brake with ABS with maximum efficiency, you need to understand the principle of operation of this system, which is quite simple. On each of the hubs of a car with ABS there are special protrusions like gear teeth. When the car is moving, they move under inductive sensors that transmit impulses to the car control system. There are several sensors, and when the wheel stops rotating during braking, the transmission of impulses stops, they work relief valves and the braking force is reduced. It is at this moment that the driver hears a characteristic crack. Thus ABS system prevents locking of the wheels, allowing the driver to control the process of driving.
How to brake correctly in a car equipped with ABS
Before dealing with the question - how to properly brake in winter on front wheel drive, you should remember the simple rules of "winter" behavior on the road, which are often neglected modern drivers:
- keep a distance that differs from the summer one by a slightly greater distance;
- tires must match the season - not necessarily studded, but continue to operate the car on summer tires winter is unacceptable;
- avoid hard braking when making maneuvers, especially when entering turns;
- do not press the brake pedal excessively when the vehicle overcomes obstacles / road surface irregularities.
The last point is especially relevant for cars with ABS. Do not be naive to believe that if the car is new and expensive, all the security systems and driver assistance available in it will help maintain controllability in a critical situation when the driver himself does not show elementary attention to traffic situation. In addition, there are some features, in addition to those listed above, that will allow you to brake on ice with ABS more correctly. These include the following:
Attention! The unconditional effectiveness of the ABS is sharply reduced on such surfaces as sand, ice, pronounced bumps - braking on them should be carried out taking into account the fact that the ABS may not work correctly.
How to brake properly in winter on mechanics
When braking in winter time when the road is icy or snowy, it must be understood that the stopping distance increases significantly, and measures to stop the car should be started in advance. It is most optimal to use a combined braking method, that is, in addition to the brake pedal, you should use a gearbox, especially if the distance allows. Such braking includes not only pressing the brake pedal, but also switching to downshifts.
But it should be understood that downshifting should be gradual, with appropriate indicators on the speedometer - if you abruptly switch to a low gear when the speed of the car is high, there is a chance of “knocking down” the engine, which will lead to a complete loss of controllability. In winter, it is necessary to completely forget about such a braking technique as “pedal to the floor”. This is not only inefficient, but also dangerous, since when the wheels are blocked, driving becomes almost impossible.
To know how to brake on ice if the car is not equipped with ABS, you should remember how this system works. It is enough to apply the brake frequently and intermittently when you need to quickly reduce speed in order to avoid losing control and slow down. When on a slippery road, it is very important to remain calm and avoid sudden pressure on the brake pedal and steering wheel movements, remembering that such actions in most cases contribute to loss of control over the car.
Special attention to difficult sections of the road
If traffic occurs predominantly in urban areas, special care must be taken at intersections. They represent increased danger even in summer period In winter, the risk of an accident here increases many times over. In order to properly brake with ABS in winter, the process must be started several tens of meters before the intersection itself. It is enough to press the brake pedal lightly, allowing the ABS to do the rest.
Important! If the car slows down jerkily, you should not panic - this is normal, and any actions of the driver at this moment can prevent a quick stop.
At intersections, special care must be taken not only at the moment of stopping. You should not strive to start one of the first, as soon as the red starts flashing. Other members traffic they may not have time to complete the maneuver and completely stop moving, especially if their car is not equipped with ABS.
Winter and ice on the roads is the most dangerous time for drivers. Due to lack full clutch wheels with road surface, the car starts to behave inappropriately on high speeds. If there is a need to brake sharply, then the braking distance increases, and the speed of the car can increase sharply due to the force of inertia. To avoid accidents, experts advise to adhere to simple rules while driving and braking on an icy road.
First, you need to switch to a less aggressive driving style. Even light snow, slush or ice lead to the loss of 100% grip on the surface. The braking distance increases and you won’t be able to stop instantly, even if you have studded winter tires.
Secondly, you need to start braking in advance. Sudden application of the brakes is the cause of skidding. You need to slow down with the help of short and not long presses on the brake. The wheels should not suddenly block, but gradually slow down the speed of rotation.
Third, learn the combined stopping method. Its essence lies in the fact that having a sufficiently large area for braking, you need to shift to lower gears in advance and gradually slow down. The most important thing is timely shifting of gears, it is worth switching to a lower gear only with the appropriate indicator on the speedometer, otherwise there is a possibility of “knocking down the engine”, that is, a sharp shift to a lower gear with increased traction leads to a complete loss of controllability.
Remember to keep your distance between cars, and don't drive too fast unless you have to.
If your car is equipped with anti-lock wheels - ABS, you should not rely on it completely. In some cases, the braking distance may be even longer. The essence of ABS is that braking occurs intermittently, only the system itself does this with the help of sensors. Unfortunately, on a slippery road, sensors do not always read information correctly. In order not to lose control, you need to sharply press the brake pedal and then squeeze the clutch. The system will then initiate impulse braking, but the wheels will not lock and the braking distance will be much shorter.
Most dangerous place in the city - these are crossroads. Because of the ice, you need to be extremely careful, start slowing down in advance. You should not immediately step on the gas when the green light turns on, because other motorists may not have time to stop in time, and pedestrians may slip on the ice.
