How to drive a car on a slippery road?
When the road is covered with melting ice, try to stay on the lane with more intensive traffic. There the ice crust melts faster, and therefore the movement is safer.
If you need to stop, look for a place on the road free of ice and snow. If there are no such areas, it is preferable to stay on dry rolled snow.
Do not stop on the climbs. Getting under way on the rise in conditions of poor adhesion is difficult and dangerous.
On a slippery road, try to maintain a constant speed, use the gas pedal gently, smoothly. Slow down in advance before turning and intersections. Crossroads are especially dangerous in winter for two reasons: firstly, there is a threat of collision with other cars, and secondly, the coating in front of intersections is usually slippery due to the constant braking of cars.
Before lifting, select the appropriate gear and speed. The calculation must be very accurate so that you do not have to add gas during the ascent.
Every year the number of drivers in our country increases by an average of 300 thousand people. Some of them had to learn to drive a car in the winter, in the snow and ice, and they got the most basic driving skills in such weather. But most of the new owners of fresh driver's license with the onset of cold weather are faced with ice for the first time. At the next lesson of our driving school (previous, see “Science and Life” No. 12, 2001), the candidate for the master of sports in car racing tells Dmitry Zykov about the features of a “winter” ride to newly-made drivers. However, it is also useful for experienced drivers to master some specific "winter" techniques.
The time when motorists put their iron horses into the garage for the winter, has passed irretrievably. Most drivers now drive in any season, including in winter. However, winter riding requires special attention, accuracy and certain skills. On some features of driving on a slippery road, we stop.
It is known that in winter it is safer and easier to drive a four-wheel drive car than a single-axle drive car, and of the latter, front-wheel drive cars are preferable for winter. However, neither full nor front-wheel drive will not help if the driver makes a mistake in elementary situations. Note that the techniques of driving four-wheel drive vehicles have a lot of features and in emergency cases are significantly different from the methods of driving a car with only one pair of wheels.
On the winter road, many situations that in the summer on a dry road could simply be ignored, are fraught with the most serious consequences.
All further reasoning and recommendations are based on the fact that during the movement of the wheels of the car must rotate (however trite it may sound). The fact is that in a rolling wheel the contact patch with the road is motionless, therefore, the friction force arising in this place is maximum (the magnitude of the static friction force is known to be maximum). It is necessary for the wheel to slip, as the force of friction drops sharply - on the ice by several orders of magnitude compared to dry asphalt - and can no longer have any effect on the car.
So, let's look at some of the most typical situations, errors in which can lead to an accident.
On the icy or just slippery road, the car does not react to the turn of the steering wheel and continues to go straight (Fig. 1). Usually in such a situation there is a desire to turn the steering wheel even steeper. You can not do this! Steeply turned wheels even easier to slip on the road, and this will lead to a complete loss of control. In this case, return the steering wheel to its original position and try to turn it smoothly again. It usually turns out.
Many drivers, remembering lessons in a driving school, try to enter smoothly in turns, gradually increasing the angle of rotation of the wheels (Fig. 2a). But it is enough to make a mistake in choosing the speed of cornering, and the front wheels can slip into a slip. In this situation, the error lies in the incorrectly chosen trajectory of movement. It is more correct at the moment of entering the turn to turn the steering wheel to a greater angle (Fig. 2b), and on the arc either not to change it, or to reduce it. So that at the entrance to the turn the front wheels do not fall off into the slip, you need to “load” them with the weight of the car. This is easy to do: at the last moment, before turning the head, close the throttle abruptly or shift down. (Open or close the gas - press or release the accelerator pedal, increase or decrease the fuel supply and increase or decrease the engine rpm, respectively.) The car will bite its nose, the front suspension springs will shrink, the front wheels grip will reach maximum. At this moment (it lasts about 0.1 seconds) and you should start the turn. Immediately after the start of the turn, the gas is slightly opened (slightly pressing the accelerator pedal). In the aggregate, such a technique is called “load-turn-thrust” (Fig. 3).
On a slippery road you need to very carefully use the brakes, especially in the corners. In many cases it is better not to touch the brake pedal at all. For example, if the turn already made a mistake, described above, and the wheels are turned all the way, braking with wheel lock (as it is sometimes called skid) will lead to a complete loss of control. The car will simply slide along the road like a village sled. If the car got into a deep (in amplitude) skid, braking will translate it into side slip. If the car began to rotate, it is better to squeeze the clutch for a short time than to press the brake. Once again: while the car is moving - the wheels must rotate.
As a nightmare, forget about coasting in neutral or with the clutch disengaged. On the drive wheels should always be "stock thrust". They operate the gas pedal, any schoolchild knows this, but there are many ways to work with the accelerator pedal, and they are different for machines with front, rear or all-wheel drive. It is especially important when driving in difficult conditions to learn how to operate simultaneously with the steering wheel and the accelerator pedal.
When the rear-wheel drive car is skidding on a slippery road, the steering wheel is turned toward the skid and the gas is completely closed. The drive wheels will slow down and skidding will stop. On a four-wheel drive car, you need to turn the steering wheel in the direction of a skid, just cover up the gas, that is, leave some traction on the wheels. The rear wheels will slow down the rotation, the development of the skid will stop, and the front will have a stock of traction, and they will “pull” the car. On the front-wheel drive car should "add gas." Two scenarios are possible here: the first is that the front wheels will start to slip, the skid will stabilize (the car will go sideways) and then level off. The second option is that with normal adhesion of the front wheels to the road surface, when gas is added, they simply pull the car to the desired path. On a front wheel drive car, the front wheels should be pointing in the direction you want to go. On a slippery road, the gas pedal works very smoothly, avoiding without the need for sudden pressure.
Very useful on slippery roads can be the clutch pedal. It turns out that it can be used not only to change gears, but also to control the car on a slippery road:
- if after drift the car began to rotate, a short-term (!) disengagement of the clutch can stop the rotation;
- when starting off on ice, the clutch will help avoid slipping of the drive wheels: while holding the pedal, make sure that the wheels do not slip;
- when losing traction in the virgin snow (when the engine speed begins to fall strongly) short-term disengagement of the clutch will help raise the momentum;
- during emergency braking, the clutch will soften the inclusion of lower gears.
At the last moment we will dwell a little more.
This technique is called engine braking. When you want to slow down, cover the gas, the engine speed will fall, and the car will go slower. Then make rebidding, lower gear, for example, after IV - III, and again cover the gas.
Re-hauling is a technique that is used when shifting gears from higher to lower. With its help, it is possible to eliminate the sharp deceleration of the drive wheels and the disruption of them in slip. The sequence of reception is as follows: disengage the clutch, shift the gearshift lever to the neutral position, engage the clutch (just release the pedal), abruptly open the throttle for a short time, then squeeze the clutch again and remove the throttle, engage downshift, smoothly engage the clutch. Successively moving to lower gears, up to the 1st, you can slow the car down to almost a complete stop, even on ice. This technique is very useful on slippery slopes, for slowing down before sharp turns and even just before the traffic lights in the city, where in winter there is often a so-called snow run-up.
As for the actual braking, then on slippery roads only the impulse method should be used. Perform this technique will have to learn, but "worth the candle worth it." There are two methods of pulse braking: intermittent and stepped. In the case of intermittent braking, you need to very briefly, sharply and repeatedly press the brake pedal (Fig. 4a). The wheels will stop only momentarily and begin to rotate more slowly than before each previous brake press. As a result, the car will stop faster than when braking "on the skid." It is easy to learn this technique - choose a safe slippery platform and practice first at a low speed, increasing it gradually, as you learn to feel the moment of wheel breakdown in gliding. This is one of the most important elements of driving skills.
When you learn to accurately determine the face of the force on the brake pedal, after which the wheels begin to slide, you can proceed to working out the reception of stepped braking. Its essence boils down to repeated quick pressing of the brake pedal with ever-increasing effort (Fig. 4b). Each time, without letting the wheels slip a little, you need to slightly release the pedal and instantly repeat pressing with a little more effort. This method is not easy, it requires serious training, but with its help it is possible to confidently stop the car even on the slippery surface itself.
On front-wheel-drive cars, it is desirable to master the “gas-brake” method - simultaneously pressing the pedals (the brake with the left foot, the gas pedal with the right foot). This technique does not stall the engine, and most importantly - allows you to easily turn the car on the arc of the rear (!) Wheels. If the front wheels of the car slid when entering a corner and the car stopped “listening to the steering wheel” without releasing the gas pedal, gently press the brake with your left foot. The rear wheels will slide into a skid, the car will take the correct position in the turn, while at the same time losing some speed. After that, gently open the gas. The front wheels "stretch" the car. A few hard workouts will help you catch the sense of skidding, teach you how to control it. Then braking with your left foot will make it possible to drive a front-wheel-drive car in a “controlled drift”. In this way, it is possible to confidently take even very sharp and dangerous turns. Mastering the technique is also not easy, but no less useful than pulse braking. First, you will constantly have the engine stall, but when you learn to dose the force of your left foot on the brake pedal, everything will work out. Practice it.
In winter conditions, the parking brake lever in capable hands turns from a passive control to an active one. This is especially important for cars with automatic transmission and front-wheel drive cars. He can replace braking with his left foot. Short-term braking of the rear wheels with a handbrake will cause them to skid, and the car will take the correct position on the turning path. This technique also requires training. Here you need to learn how to operate the lever confidently, vigorously and very quickly, as accurately dosing the time of its inclusion. In long smooth corners, it is enough that the rear wheels just start to slip into a skid, and in order to fit into a sharp turn, sometimes you need to make the car slide with a “fan”, then the handbrake needs to be held much more.
On a slippery road, it is advisable to move to higher gears with a short pause on the "neutral" in order to make the acceleration softer. When turning down gears, it is recommended to use reboots. Winter conditions require the use of combined braking with the sequential inclusion of low gears, which will counteract the occurrence of a skid. Especially important is the combined braking for front wheel drive cars.
Now let's talk about the tires, it depends on them in many respects how successfully this or that maneuver will be performed. A self-respecting driver should have two sets of tires (summer and winter), preferably with wheels, so as not to create problems for yourself at tire when changing the season.
Special winter tires will help to increase stability and controllability on slippery roads. Hard tires with standard anti-skid spikes are suitable for country, heavily iced roads or roads with rolled snow. Spikes should be located on four lanes, it is desirable that there should be at least 10-12 in the patch of tire contact with the road. For driving in a city where roads are cleaned and the main danger is snow and salt porridge, softer tires with high lug grousers are better suited. Studded wheels should not be wide to increase the pressure on the ground. And wider soft shaped tires increase the patch of contact with the road. It is impossible to use tires in winter more widely recommended by the manufacturer of the car. Due to the low specific pressure on the ground, they will constantly slide along the road.
Some drivers install studded tires on the driving axle in winter, while summer tires are left on the second axle. So in no case should not. All four tires of the car must be the same model. "Raznokolesitsa" sometimes leads to paradoxical results. For example, in the rear wheel drive vehicle there is a tendency to slip the front wheels, and in the front wheel drive vehicle, the rear wheels skid.
In winter, even more than in summer, it is dangerous to pump the wheels. A hard wheel with increased pressure has a smaller, as provided by the manufacturer, patch of contact with the road and can easily slip into a slip.
In winter, as in summer, tubeless tires are preferable. They are more reliable than tires with cameras, they are not afraid of small punctures with wires from metal brushes and even nails, they behave softer on uneven surfaces, easier tires with cameras and, therefore, have a less inertial effect on the suspension.
Owners of expensive and not very expensive cars equipped with anti-lock systems (ABS), have some advantage when driving on slippery roads. The ABS prevents the wheels from locking, and this allows you to brake in a turn, often saves the car from skidding, gives an advantage in urban traffic with a shortage of distance.
But along with the advantages of the ABS has disadvantages. For example, when the wheels of one side hit the ice or the car was thrown on the roughness of the ABS, while maintaining the stability of the vehicle, it impairs its braking dynamics.
To avoid such situations, on uneven slippery roads (for example, a rolled out snow-covered country highway, on which a crawler tractor has recently driven), pulsed braking is used, although this contradicts instructions. The impulse operation of the brake pedal causes the ABS to turn on for maximum braking power and greatly reduces the attenuation of the brake dynamics.
On our roads, there are more and more modern imported cars equipped with additional control systems: automatic gearboxes, ABS, hydraulic or electric power steering and brakes, anti-skid systems, cruise control, limited slip differentials, etc. However, any driver driving such a car must understand that it is impossible to rely only on automation.