The device and operation of an automatic transmission. Automatic transmission: device and principle of operation

30.09.2019

automatic transmission, also referred to as an automatic machine or a chopper, is a type of auto transmission that allows you to reduce the load on the driver when driving, since gear selection occurs automatically, without the participation of the driver. This fact affects all the characteristics that cars with automatic transmission have.

Photo gallery:

Advantages of automatic transmission

increasing comfort when driving a car and freeing the driver from the control of third-party functions;
smooth gear shifting and coordination of the load on the motor with the speed and force of pressing the pedal;
protection of the motor from any overload;
admission to partial or full manual control of the transmission.

Automatic transmission types

Automatic transmissions of modern cars can be divided into several types, differing in the control system and control over the operation of an automatic transmission. The first type of transmission is controlled by a hydraulic device, and the second by an electronic distributor.

Types of automatic transmission

The “innards” of both transmissions are identical, however, there are several layout differences that each automatic transmission has.

All 3 types of automatic transmissions will be briefly considered in more detail in order to understand their difference from each other and the principle of operation.

Types of automatic transmission - briefly about the main thing.

Hydraulic automatic - classic automatic transmission

The hydraulic type of automatic transmission is the simplest automatic transmission. Such a box excludes a direct connection between the engine and the wheels. The torque in it is transmitted by two turbines and a working fluid. Due to the improvement of the mechanism, a specialized electronic device appeared in such a box, which was also able to add such operating modes as: “winter”, “sport”, economical driving.

One of the main disadvantages, in comparison with - is a little more fuel consumption and acceleration time.

Robotic automatic transmission

MTA popularly sounds like a DSG robot, structurally it is most similar to a manual transmission, but from the point of view of control it is a typical automatic transmission, which, as a result of evolution, not only reduces fuel consumption, but also a number of other advantages, naturally with its own nuances.

CVT transmission

Although it is considered an automatic transmission, they are fundamentally different both in design and in principle of operation. In such a gearbox, there are no steps, since there is no fixed gear ratio. Drivers who are accustomed to listening to the engine of their car cannot track its operation, because the torque in the variator box changes smoothly and the engine tone does not change.

Automatic transmission components

torque converter, which replaces the clutch, and does not require the participation and control of the driver.
instead of the gear block in the automatic transmission is installed planetary gear set. This part helps to change the attitude in the automatic transmission when shifting the transmission.
front and rear clutch, as well as a brake band, thanks to which gear shifting is carried out directly.
The last and most important detail is control device, which is an assembly of a gearbox pan, a pump and a valve box that performs control functions. This component transmits traffic data through signs that transmit a signal to the action of the automatic transmission itself.

The device and operation of an automatic transmission.

Of all the main components, we will pay the most attention to the torque converter of the box.

The hydrotransformer includes:

centrifugal pump;
stator;
centripetal turbine;
pump wheel;
turbine wheel;

The stator is a guide apparatus, which is located between these parts. The pump wheel is connected to the crankshaft of the engine, and the turbine wheel is connected to the gearbox shaft. The reactor has 2 functions. It can rotate or be blocked by a freewheel.

The main task of the torque converter is to absorb strong shocks that are transmitted by the transmission to the engine and vice versa. This machine extends the service life of these parts. With the help of liquid oil, torque is transmitted from the engine to the automatic transmission.

In order for the automatic transmission to work for a long time and properly, it is necessary to regularly undergo diagnostics at a service station.

Pay attention to the following details:

gears must be switched in 1 second, the maximum time is 1.5 seconds;
switching notification is carried out by light pushes;
gear shifting should be silent.

How an automatic transmission works

In a hydromechanical automatic transmission in the classic version, gear shifting occurs due to the interaction of planetary mechanisms and a hydromechanical drive using electronic devices.

How to use a classic automatic transmission correctly?

Features of automatic transmission operation

automatic transmission needs to be well warmed up before you start driving (this is especially true in winter).
When driving an automatic transmission, translate shift selector lever in positions P and R while driving, strongly Not recommended.
No need to shift into neutral in time to descend from the mountain, supposedly fuel economy, - it will not be there anyway, but problems with braking may arise.
Engine braking is not possible in all transmission modes. This point of operation must be studied in detail in the instruction manual for a particular car; neglecting such a feature can cost an expensive repair.

Automatic transmission problems and solutions

The most common automatic transmission problems are considered to be:

a pronounced jerk when shifting gears, as well as noise when moving the selector lever to another position;
quite often in automatic transmissions, the brake band of the front and rear clutch breaks;
failure of the electric or hydraulic unit.

An article on how to use the automatic transmission correctly - symbols on the automatic transmission panel, starting the engine, moving and stopping, possible errors. At the end of the article - a video about using an automatic box.

At the moment, there are three types of automatic transmissions: "classic", with "stepless variator", with "robotic mechanics". Depending on the modification and manufacturer, these types of transmissions may differ slightly (a different number of gears, a slightly different lever stroke - straight or zigzag, symbols, etc.), but the main functions will be the same for everyone.

The growing popularity of automatic transmission is understandable - it is more convenient to operate (than "mechanics" - manual transmission), especially for beginners, reliable and protects the engine from overload. Everything seems to be simple! However, drivers still make mistakes, and even the most reliable mechanism can fail if it is not properly operated. Next, we will consider how to properly use the automatic transmission and how to properly operate it.

To learn how to use the "machine" correctly, you first need to figure out what the alphabetic characters (English letters) and numbers on the automatic transmission panel with the gear shift knob mean. Just note that depending on the brand of the car, the numbers and letters may vary.

"P"- "parking". Turns on when the car is parked. A kind of analogue of the parking brake, only with the blocking of the shaft, and not with the pressing of the brake pads.
"R"- "reverse". Turns on for reverse. It is commonly referred to as "reverse speed".
"N"- "neutral". Neutral gear. Often referred to as "neutral". Unlike in P park mode, in neutral N mode, the wheels are unlocked so the car can coast. Accordingly, the machine can also spontaneously roll down a slope in a parking lot if the wheels are not fixed with a handbrake.
"D"- "drive". Forward mode.
"A"- "automatic". Automatic mode (practically, the same as the "D" mode).
"L"- "low" (low). Downshift mode.
"B"– Same mode as "L".
"2"– the driving mode is not higher than the second gear.
"3"– the driving mode is not higher than the third gear.
"M"- "manual". Manual control mode with up / down transfer through the signs "+" and "-". This mode imitates a mechanical shift mode with a manual transmission, only in a simpler version.
"S"- "sport". Sports driving mode.
"OD"- Overdrive. Upshift (fast mode).
W- "winter". Driving mode for the winter period, in which starting off starts from second gear.
"E"- "economy". Driving in economy mode.
HOLD- "retention". Used in conjunction with "D", "L", "S", as a rule, on Mazda cars. (Read the manual).

When operating an automatic transmission, special attention should be paid to studying the operating manual for a particular vehicle, as some designations may differ functionally.

For example, in the manual of some cars, the letter "B" means "Block" (blocking) - a differential lock mode that cannot be engaged while driving.

And if the designations “1” and “L” are present in an all-wheel drive car, then the letter "L" may not mean "Low" (decrease), but "Lock"(lock) - which also means differential lock.

Starting an engine with an automatic transmission has the following features:

In a car with automatic transmission, there are only two pedals: "brake" and "gas". Therefore, the left leg of the driver is practically not used. When starting the engine, the “gas” pedal is not pressed, but in some brands of cars it is necessary to press the brake pedal, otherwise the engine will not start (read the instruction manual).
However, driving instructors advise making it a rule to always press the brake pedal before starting the engine with automatic transmission. This will prevent the machine from moving unintentionally in neutral "N" mode, and will also allow you to quickly switch to "D" or "R" driving modes. (Without pressing the brake pedal, you will not be able to switch to the indicated modes and move off).
In cars with automatic transmission, protection is provided - automatic blocking of engine start in case of incorrect position of the gear lever. This means that the engine with automatic transmission can only be started if the gear lever is in one of two positions: either “P” (parking) or “N” (neutral). If the PP lever is in any other position intended for movement, the blocking protection against incorrect start will be activated.
This protective function is very useful, especially for beginners, and especially in cities with a large “car density”, where cars are packed tightly together in parking lots and in traffic. After all, even experienced drivers sometimes forget to “take the car off the speed” before starting the engine, as a result of which, when starting, the car immediately starts driving and crashes into the nearest car or obstacle.
It is possible to start the engine with automatic transmission both in the “P” (parking) mode and in the “N” (neutral) mode, however, manufacturers recommend using only the “P” mode. Therefore, it is better to set one more rule for yourself - park and start the engine only in the “parking” mode.
After turning the key in the ignition it is recommended to wait a few seconds before starting the starter to give the fuel pump time to turn on and pump up compression.

It should be remembered that on some brands of cars with automatic transmission, gear shifting is not possible without inserting and turning the key in the ignition (unlocking the gearbox). Also, on some brands it is impossible to remove the key from the ignition if the PP lever is in the "D" position. (Read the user manual).

Most drivers who switch from "mechanics" to "automatic" at first automatically perform the actions that they are accustomed to doing repeatedly when driving a car with a manual transmission. Therefore, such drivers, before starting to drive with automatic transmission on the road in the general traffic flow, are recommended to pre-train alone.

So, the standard procedure for starting off on a car with automatic transmission is as follows:

Insert the key into the ignition switch.
Depress the brake pedal with your right foot (the left foot is not used when driving with automatic transmission).
Check the position of the gear lever - it should be in the "P" - "parking" position.
Start the engine (with the brake pedal depressed).
Also, with the brake pedal depressed, switch the PP lever to the “D” - “drive” position (forward movement).
Fully release the brake pedal, after which the car will move off and start moving forward at a low speed - about 5 km / h.
To increase the speed of movement, you need to press the "gas" pedal. The harder you press the gas pedal, the higher the gears and speed will be.
To stop the car, you need to remove your right foot from the "gas" pedal and squeeze (her) the brake pedal. The car will stop.
If you plan to leave the car after stopping, then with the brake pedal depressed, move the gear lever to the "P" - "parking" mode. If a stop was required in a traffic jam, at a traffic light or a pedestrian crossing, then, naturally, the PP lever does not need to be switched to “parking”. After you decide to continue driving again, release the brake pedal and press the "gas" pedal to increase speed.

Many modern automatic transmissions have an imitation of the "M" mechanical shift mode (as on a manual transmission) for up/down gears using the "+" and "-" buttons on the PP lever. That is, the driver is given the opportunity to manually upshift or downshift, taking this function from the "machine". At the same time, the transition to a mechanical gearshift mode can be made on the move, when the car is already driving in the “D” mode.

To prevent damage to the engine when switching to manual mode "M" on the go, all automatic transmissions have special protection. Switching to manual control "M" is relevant in the following situations:

When driving off-road in low gear to avoid slipping.
When coasting down a hill, with engine braking. It is not recommended to use the neutral mode "N" for coasting, as it is harmful to the automatic transmission. And the coast in the "D" mode is not very convenient, as there is a gradual decrease in speed.
For comfortable cornering and other manoeuvres, including for quick acceleration when overtaking.

The most common mistake leading to automatic transmission failure is switching on the "D" - "drive" mode (forward movement) without a complete stop when reversing. And, the same thing, just the opposite - the inclusion of the "R" (reverse) mode without a complete stop when moving forward.
The second common mistake (rather delusion) is related to the “N” (neutral) mode. The fact is that this mode is an emergency mode to unlock the wheels for short-term towing or rearrangement of the car in case of any malfunction. And just for this!
But many inexperienced drivers use the neutral mode "N" in traffic jams during short stops, which leads to water hammer and premature wear of the automatic transmission. In traffic jams with frequent stops, you need to use the "D" mode along with the brake pedal. If you need to stop - the brake pedal is pressed, if you need to slowly move forward - the brake pedal is simply released, and the car slowly rolls forward. And you can drive like that all day long.
The third mistake transition to the neutral mode "N" from the mode "D" on the go, on the highway. This is dangerous (especially at high speed), as it can stall the engine, as a result of which the power steering and brake boost will turn off, and the car will become almost uncontrollable.
Another mistake - towing a car with automatic transmission for a distance of more than 40 km and at a speed of more than 50 km/h. In the “automatic” box, unlike the manual transmission, the oil supply system works under pressure, but it does not work when towing. Accordingly, the parts of the “machine” rotate “dry”, without lubrication, as a result of which they wear out very quickly.
A common mistake is attempt to start a car with automatic transmission "from the pusher". And although such attempts often lead to the desired result (the engine starts), it still has a destructive effect on the automatic transmission mechanism, and with such frequent operation, the “machine” may not work out even half of the pledged resource.

Conclusion

It is quite possible that for someone the automatic transmission will seem like a complex and finicky mechanism, despite the simplicity and ease of use. But this is only at first glance. In fact, "automatic machines" have proven themselves to be quite reliable units, but, of course, subject to their correct and competent operation. It is especially convenient to use automatic transmission in big cities, where you often have to stand in traffic jams.

Video on how to use the "machine":

Today, most drivers have no idea how they would drive a car that does not have an automatic transmission. Some beginners are horrified at the mere thought of constantly shifting gears manually. Many experienced drivers also realized long ago that driving with an automatic transmission is much more convenient. Despite all this, people are tormented by the question - how to properly operate the automatic transmission? In this article, this is exactly what will be discussed.

Operating modes

To understand how to operate the automatic transmission, you need to figure out what modes exist.

It should be noted right away that the “P”, “R”, “D” and “N” modes are mandatory in each box. To select one of the modes, you just need to move the gear lever to the appropriate position. The difference from a mechanical box is that the movement of the lever occurs in one line.

The mode selected by the driver will be displayed on the control panel. This makes it possible to closely monitor the road and not be distracted to look at the lever.

"P" - parking. Used for long periods of parking. It is from the parking lot that it is desirable to start the car. It is important to completely stop the machine before turning on this mode.
"R" - used to move in reverse. To turn on, you need to completely stop.
"N" - neutral position. When the lever is in neutral, torque is not transmitted to the wheels. Worth using during short breaks.
"D" - movement. When the selector is in this position, the car moves forward. Gear shifting is done independently. The driver only presses the gas pedal.

In cars with a five- or four-speed gearbox installed, the selector has several positions for moving forward: "D", "D3", "D2", "D1". These numbers show top gear.

"D3" - "first 3 gears." It is recommended to use in cases where it is not possible to move without braking.
"D2" - "first 2 gears." The lever should be moved to this position when the speed is less than 50 km/h. Most often used on poor quality roads.
"D1" ("L") - "only 1st gear." Used when the maximum speed is 25 km/h. It is worth moving the lever to a similar position when the car is in a traffic jam.
"OD" - "high gear". You should move into this position when the speed reaches more than 75 km / h, and exit it when the speed drops below 70 km / h. The overdrive makes it possible to reduce fuel consumption when driving on motorways.

Most new cars with an automatic have several automatic transmission auxiliary modes. These include:

"N" - standard, which is used during normal driving.
"E" - fuel economy mode. Helps the vehicle to move at a pace that significantly reduces fuel consumption.
"S" - sport. When the driver switches to this mode, he can make the most of the engine power. It is not surprising that fuel consumption in this mode will be high.
"W" - winter. It is used in those moments when you need to start moving from a slippery road surface.

Of course, there are drivers who could not get used to the automatic transmission, given all its advantages. To meet the needs of these people, the "tiptronic" mode was created. In fact, it involves the imitation of manual control. On the box, it is implemented as a groove for the selector, and is marked with plus and minus signs. Plus makes it possible to upshift, and minus to downshift, respectively.

Basic operating conditions for automatic transmission

In order to start moving on a machine in which an automatic transmission is installed, follow the steps in the following order:

Press the brake pedal.
Move the selector to the "drive" position.
Remove from handbrake.
Release the brake slowly. The car will start moving slowly.
Press the accelerator pedal.
To slow down, you need to throw off the gas. If you need a quick stop, then be sure to use the brake.
To start after a slight stop, you just need to move your foot from the brake to the accelerator.

The basic rule of using an automatic transmission is to avoid sudden maneuvers. If you constantly do them, this will lead to the fact that the gap between the friction discs will increase, and then in the differential. All this will lead to the fact that the car will twitch during each gear change.

Experienced craftsmen believe that the machine needs to be given a short “rest”. This means that the car must be allowed to idle for a few seconds. It is worth noting that even in a car with a powerful engine, sudden movements will significantly reduce the resource of the box.

In fact, this moment is very important, because most of these boxes break in winter. First of all, this is due to a significant drop in temperature and the fact that cars often skid on ice. In order to protect your car from damage as much as possible, you should adhere to the following recommendations:

Before the onset of cold weather, check the quality and level of fluid in the box, and replace if necessary;
Be sure to warm up the car before driving;
If the car is stuck, do not step on the gas in the hope of leaving. It is worth trying to downshift (if possible) or just push;
Before a sharp turn, use only lower gears.

What not to do

What not to do on a car with an automatic transmission:

First of all, you should not heavily load the box if the car has not warmed up to the required level. Even if the temperature is positive outside, the first few kilometers, the movement should be smooth and measured.
Automatic transmission does not like off-road very much. Cars with a gun, it is best to go around roads with poor pavements. If the "iron horse" is stuck, sometimes it is better to resort to the help of a shovel than to put pressure on the gas.
It is not recommended to subject the automatic transmission to high loads. If there were plans to tow a trailer, then it is better to put them out of your head.
It is strictly forbidden to start a car from the so-called pusher. Many people violate this prohibition, but it is worth remembering that this will not pass without a trace for the box.

Of course, we must not forget about the individual features of switching between modes:

you can stay in neutral only if the brake is pressed;
on the "neutral" it is forbidden to turn off the car;
turning off the engine is allowed only in the “parking” position;
when the car is in motion, do not move the lever to the “parking” and “reverse” positions.

Summing up, it is worth noting that the automatic transmission may seem rather "finicky" and having a small resource. In fact, if you use it correctly, it will please its owner for a very long time.

Video: how to use automatic transmission correctly

The automatic transmission is the part of the transmission that is able to control the torque and speed of the vehicle. This means that you no longer need to calculate the moment when to hold the clutch and release it, as well as manually shift gears.

In this article, we will consider the principles of operation of the mechanism.

The history of the creation of an automatic transmission

Transmission automation has historically occurred in three phases. The first attempt to make cars more independent was made by Henry Ford at the beginning of the 20th century. Ford T had a planetary gearbox, which required less skill from motorists to shift gears than an ordinary manual.

At the next stage, cars with a semi-automatic transmission entered production. In them, automation is aimed either at independent gear shifting, or at refusing to use the clutch, which greatly facilitated the driving of the vehicle.

Did you know? Such a semi-automatic transmission is still used on scooters.

The last step towards the transition to automatic transmission was the system proposed by the developers of the American company General Motors. It was based on the planetary model previously used at the Ford plant, as well as hydraulics, which itself turned on at the moment when it was necessary to change the gear. Both principles underlie the modern automatic transmission.

Arrangement of units and mechanisms

An automatic transmission conditionally consists of three main parts:

Mechanical. Her responsibilities include changing the speed of the vehicle, as well as direct gear shifting.
hydraulic. This part of the automatic transmission transmits torque between the components of the gearbox without any driver action.
Electronic. This component is the brain of the gearbox, which monitors the operation of the mechanical and hydraulic systems, and also transmits signals to other parts of the car.

Components of an automatic gearbox:

Did you know? In the USSR, the first torque converters began to be used on such cars as the Chaika, Volga, ZIL, as well as some other vehicles.

Principle of operation

Any automatic transmission operates on the basis of a planetary gearbox, which consists of a sun gear and combined carrier and ring gear. There are as many nodes as there are speeds of the car.

Principle of operation:

All impulses to the gearbox are received using two inputs connected to the crown and sun gears, and are transmitted through one output, which is provided by the rotation of the planet carrier.
When an impulse is received at the input to the sun gears, they begin to rotate, which leads to the rotation of the planet carrier.
The carrier, in turn, causes the ring gear to move, which entails a constant increase in the rotation speed of the carrier at the output.
If the driver needs to shift into reverse, the sun gears will move in the opposite direction.

The automatic transmission does not have a direct connection between the input and output shaft. They are united by an intermediate shaft, on which two packages of friction discs connected to the gear are closed in working condition.

Did you know? Over the past year in Europe, 80% of all purchased cars work on an automatic gearbox. On the territory of the CIS countries, purchases of cars with automatic transmission account for only 10% of the total number of vehicles sold.

It is these disks that transmit power. Friction discs at the inlet are smaller in diameter than at the outlet. This is due to the increase in rotational power during the transfer of an impulse from the input to the output.

Advantages and disadvantages

Let's take a look at the pros and cons of using a car with an automatic transmission.

Pros:

convenience. You no longer need to be distracted by shifting gears and using the clutch. The driver can be fully concentrated on the road;
easier to get moving. Responsible for this process in an automatic transmission is electronics, and not the correct pressing of the clutch or gas pedal;
vehicle components have a longer service life due to electronic control. Very often, drivers, especially beginners, switch gears at the wrong time, which leads to a malfunction of the engine, or delay the clutch, or work without it at all, which leads to its burnout.

Minuses:

cars with automatic transmission are expensive. Moreover, they are also more expensive to maintain than manual transmission vehicles;
there are difficulties in bad weather. The main way to get out of a skid or mud is to “swing”, which is impossible when using an automatic gearbox.

Important! When shifting gears using the selector, do not press on the gas pedal.

A car with an automatic gearbox is designed for people who value comfort. To determine which type of transmission is right for you, you should practice driving with both manual and automatic transmissions.

The principle of operation of an automatic transmission: video

An automatic transmission is a device that allows you to independently, that is, without the direct participation of the driver, select one or another gear for movement. We will try to tell everything about automatic transmission, starting from the history of development, ending with how to use automatic transmission correctly.

How did the automatic transmission

The modern automatic transmission appeared thanks to three directions in mechanics, which were developed independently of each other and subsequently became a single unit that allows you to shift gears automatically, depending on the speed of the car.

The first development in this direction was the appearance of a planetary gear, which became the main mechanism Ford T cars even at the beginning of the 20th century. The essence of the operation of this device was to ensure that the gears turn on smoothly with the help of two pedals. One of them worked for upshifts and downshifts, and the other activated the reverse gear. In those days, this was really a novelty, because then synchronizers were not yet used in car transmissions to ensure smooth switching.

The second direction was the appearance in the 30s of the last century of the first semi-automatic gearbox, when the hydraulic clutch began to control the planetary mechanism. At the same time, the use of the clutch in the car was not canceled. This invention belongs to the well-known company General Motors.

Well, the latest invention was fluid coupling application in this type of transmission, which minimized the appearance of jerks. In addition, this time, in addition to 2 steps, an overdrive was introduced for the first time - an overdrive, while the gear ratio did not exceed one.

Chrysler, which introduced this innovation in the 1930s, introduced a new type of transmission, the semi-automatic, although it is now considered mechanical.

Ultimately, the automatic transmission, in the form that it is used to seeing, appeared in the 1940s and was created by General Motors. In the same period, the company abandoned the use of a fluid coupling and began to use a special torque converter, which excluded the possibility of slipping of the element. Later, a standard was introduced that implied five selector positions on automatic transmissions: "D", "L", "N", "R" and "P".

The device and principle of operation of the automatic transmission

The design of the automatic box includes the following elements:

torque converter- plays the role of a clutch and ensures the smooth running of the mechanism. The main function of the torque converter is considered to be the smooth transmission of torque from the flywheel to the automatic transmission shaft.
Planetary gearboxes- sequential transmission of torque.
Friction type clutches. In another way, they are called "packages". Provide gear change. Provide communication between gear mechanisms and break it.
Freewheel. It plays the role of a synchronizer and reduces the load that occurs when the "packets" come into contact. In addition, in some designs, automatic transmissions exclude the possibility of engine braking, leaving overdrive in operation.
Shafts and drums to connect all parts of the box.

Regardless of the design of the automatic transmission, they shift gears according to the same principle. All switching is carried out by moving the oil inside the automatic transmission, by turning on certain spools. Control of spools can be of two types: electric or hydraulic.

The hydraulic drive uses oil pressure generated by a centrifugal governor that is connected to the gearbox shaft. In addition, pressure is created at the moment when the driver presses the gas pedal. Thus, the automation receives information about the position of the accelerator and performs the necessary switching of the spools.

The electric drive uses solenoids that are installed in spools and connected to the automatic transmission control unit. In most cases, this block has a close relationship with . It turns out that gear shifting will be carried out depending on the throttle position, gas pedal, vehicle speed and many other parameters.

How to use an automatic transmission correctly + Video

Without a doubt, an automatic transmission provides driving comfort, although many drivers still prefer a manual transmission, feeling the car and completely controlling the transmission. Despite this, there is still a large percentage of those who really fell in love with automatic transmission.

If you are just planning to master a new type of transmission, then you need to take into account a few nuances that will save you from premature failure of the assembly, because planetary gears are very sensitive to mechanical overloads.

In total there are several positions of the selector:

"N" - neutral gear A. Needs no comment, it's the same as a normal mechanical box.
"P" - "parking". This position allows you to block the drive wheels and exclude the possibility of rolling the car when parking.
« D "- used to move the car forward. In fact, it is the main position of the selector, which is responsible for all automatic switching.
"L" - downshift. It is an analogue of the first gear of a manual transmission. Designed to overcome sections of the road where driving at high speed is unacceptable.
« R" - reverse gear. Used to move the car backwards.

Having dealt with the provisions of the selector, it's time to learn how to use it correctly. First of all, starting the engine is permissible in the "P" or "N" positions and with the brake pedal fully depressed. To switch to the “D” position, without releasing the brake, take your foot off the gas and press the selector lock button, move it and start moving.

At the same time, it should be borne in mind that with any change in the position of the selector, in no case should you press the gas pedal.

A few important points:

For an automatic transmission, the "swing" method when overcoming a snow barrier is unacceptable. This is due to the fact that it is necessary to completely stop the car when moving the selector from position "D" to "R". Otherwise, you can simply render the entire transmission mechanism unusable.

You can only move in winter good winter tires with a sufficiently large tread pattern. In this case, you need to set the selector to position "W" or "1", "2", "3". This is due to the fact that when the wheels hit the ice, the automation “thinks” that the car is not loaded and accelerates, which naturally leads to a gear change. Thus, a sharp skid of the car is obtained.
and is recommended only on a tow truck or by partial loading of the drive wheels. The fact is that the gearbox oil pump is driven by the internal combustion engine, and when it is turned off, the oil supply is turned off, which accordingly leads to wear of the gearbox mechanisms. However, the developer took this factor into account, leaving a few towing rules. For example, the fact that the speed should not exceed 40 km / h (although exceptions are possible), the box should not be filled with oil as usual, but up to the very neck and the maximum towing distance should not exceed 30 km. At the same time, it is necessary to stop and give time to the mechanism to cool down, since at these moments it overheats very much. Many models with automatic transmission cannot be towed at all, for example, all-wheel drive. Although you can disconnect the cardan and immerse the front wheels.
Automatic transmission not for extreme driving and in no case will tolerate such tricks as pressing the gas and brake pedals at the same time. All this will lead to overheating and subsequent failure of the unit.

That's all you need to know about automatic transmission.