Automatic checkpoint. Automatic transmission for a beginner: types, principle of operation

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.

1. "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.
2. "R" - used to move in reverse. To turn on, you need to completely stop.
3. "N" - neutral position. When the lever is in neutral, torque is not transmitted to the wheels. Worth using during short breaks.
4. "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.

1. "D3" - "first 3 gears." It is recommended to use in cases where it is not possible to move without braking.
2. "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.
3. "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.
4. "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:

1. "N" - standard, which is used during normal driving.
2. "E" - fuel economy mode. Helps the vehicle to move at a pace that significantly reduces fuel consumption.
3. "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.
4. "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:

1. 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.
2. 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.
3. 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.
4. 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

An automatic transmission (abbreviated as automatic transmission) is one type of vehicle transmission. The automatic gearbox independently (eliminates the direct intervention of the driver in the process) sets the desired ratio of gear ratios, based on driving conditions and various factors.
Engineering terminology recognizes as “automatic” only the planetary element of the assembly, which is directly related to gear shifting and, together with the torque converter, creates a single automatic stage. An important point: automatic transmission always works in conjunction with a torque converter - it guarantees the correct operation of the unit. The role of the torque converter is to transfer a certain amount of torque to the input shaft, as well as to prevent jerks when changing stages.

Options

The automatic transmission is, nevertheless, a conditional concept, because there are its subspecies. But the ancestor of the class is a hydromechanical planetary gearbox. It is the hydraulic machine that is associated with automatic transmission, for the most part. Although currently there are alternatives:

• robotic box ("robot"). This is a variant of "mechanics", but switching between steps is automated. This is possible due to the presence in the design of the “robot” of electromechanical (electropneumatic) actuators, which are driven by electronics;
• variable speed drive. A subspecies of a continuously variable transmission. It is not directly related to gearboxes, but implements the power of the power unit. The process of changing the gear ratio occurs gradually. The V-chain variator has no steps. In general, the principle of its operation can be compared with a bicycle speed sprocket, which, as it unwinds, gives the bicycle acceleration through the chain. Automakers, in order to bring the operation of this transmission closer to traditional ones (with steps) and to get rid of the mournful hum during acceleration, create virtual gears.

Device

The hydromechanical gearbox - "automatic" consists of a torque converter and an automatic planetary gearbox.

The design of the torque converter includes three impellers:

Each element of the gas turbine engine (torque converter) requires a strict approach in production, synchronous integration, balancing. Based on this, the gas turbine engine is manufactured as a non-separable and non-repairable unit.

The constructive location of the torque converter: between the transmission housing and the power plant - which is similar to the installation niche for the clutch on the "mechanics".

Purpose of gas turbine engine

The torque converter (relative to a conventional fluid coupling) converts the engine torque. In other words, there is a short increase in traction, which is received by the box - "automatic" when accelerating the vehicle.

An organic drawback of the gas turbine engine, following from its principle of operation, is the rotation of the turbine wheel when interacting with the pump wheel. This is reflected in energy losses (the efficiency of the gas turbine engine at the time of uniform movement of the car is no more than 85 percent), and leads to an increase in heat emissions (some torque converter modes provoke a greater heat release than the power unit itself), increased fuel consumption. Now automakers on their cars integrate a friction clutch into the transmission, which blocks the gas turbine engine at the moment of uniform movement at high speed and higher stages - this reduces friction losses of the torque converter oil and reduces fuel consumption.

What is a friction clutch for?

The task of the clutch package is to switch between gears by communicating / disengaging parts of the automatic transmission (input / output shafts; elements of planetary gearboxes and deceleration in relation to the automatic transmission case).

Coupling design:

• drum. Equipped with the necessary slots inside;
• hub Has outstanding external teeth of a rectangular shape;
• set of friction discs (ring-shaped). It is located between the hub and the drum. One part of the pack consists of metal outer lugs that fit into the drum splines. The other is plastic with internal cutouts for the teeth of the hub.

The friction clutch communicates by compression by an annular piston (integrated into the drum) of the disk set. Oil supply to the cylinder is carried out using drum, shaft and body (automatic transmission) grooves.

The overrunning clutch has free slip in a certain direction, and in the opposite direction it is wedged and transmits torque.

Overrunning clutch includes:

• outer ring;
• separator with rollers;
• inner ring.

Node task:

Automatic transmission control unit: device

The block consists of a set of spools. They control the oil flow towards the pistons (brake bands)/friction clutches. The spools are arranged in a sequence that depends on the movement of the gearbox/automatic selector (hydraulic/electronic).

hydraulic. Applies to: oil pressure of the centrifugal governor that interacts with the output shaft of the gearbox / oil pressure that is generated during the depressing of the accelerator pedal. These processes transmit to the electronic control unit data on the angle of inclination of the gas pedal / speed of the car, followed by the switching of the spools.

Electronic. Solenoids are used to move the spools. The wire channels of the solenoids are located outside the automatic transmission housing, and go to the control unit (in some cases - to the combined control unit for the fuel injection and ignition system). The received information about the speed of the car / angle of inclination of the gas determines the further movement of the solenoids through the electronic system / the handle of the automatic transmission selector.

Sometimes the automatic transmission works even with a faulty electronic automation system. True, provided that the third gear (or all stages) is on in the manual mode of controlling the box.

Selector control

Varieties of the position of the selectors (automatic transmission lever):

• floor. The traditional location in most cars is on the central tunnel;
• stalk. This arrangement is often found in American cars (Chrysler, Dodge), as well as in Mercedes. The desired transmission mode is activated by pulling the lever towards you;
• on the center console. It is used on minivans and on some conventional cars (eg: Honda Civic VII, CR-V III), which frees up the space between the front seats;
• button. The layout has been widely used on sports cars (Ferrari, Chevrolet Corvette, Lamborghini, Jaguar and others). Although it is now being integrated into civilian vehicles (premium class).

Slots of floor selectors are:

Box operation

How to use the box - "automatic" correctly? Two pedals and many transmission modes can plunge an inexperienced driver into a stupor. At first glance, everything is simple, but there are nuances. Below are explanations of how to use the automatic transmission correctly.

Modes

Basically, the “automatic” box has the following positions on the selector:

• P is the implementation of the parking lock: blocking the drive wheels (integrated inside the gearbox and does not interact with the parking brake). An analogue of setting the car into gear ("mechanics") when it is parked;
• R - reverse gear (it is forbidden to activate while the car is moving, although blocking is now applied);
• N - neutral gear mode (activation is possible during short parking / towing);
• D - forward travel (the entire gear ratio of the box is involved, sometimes two higher gears are cut off);
• L - activation of the low gear mode (low speed) for the purpose of driving off-road or on such, but with difficult conditions.

Auxiliary (advanced) modes

Present on boxes with extensive operating ranges (the main modes may also be labeled differently):

• (D) (or O / D) - overdrive. Economy mode and measured movement (whenever possible, the box switches to the top);
• D3 (O / D OFF) - deactivation of the highest stage for active driving. It is activated by braking by the power unit;
• S - gears spin up to maximum speed. There may be the possibility of manual control of the box.

Take into account:

The “automatic” with respect to the manual gearbox slows down the engine only in certain modes, in the rest, the transmission has free slip through the overrunning clutches, and the car “freewheels”.

Example - manual transmission mode (S) provides for motor deceleration, but automatic D does not.

While driving

How to use the "automatic" box correctly in the direction of travel? Modern transmissions allow the transition from one mode to another without pressing the button on the selector lever (except R). And in order not to prevent the arbitrary start of the movement of the machine during a stop, you must press the brake pedal when switching modes.

You also need to know how to properly tow a car with automatic transmission. You must adhere to the following recommendations:

• check the oil level in the box for compliance with factory standards;
• turn the ignition key, remove the lock from the steering column;
• switch the selector to N mode;
• towing is recommended no more than 50 kilometers, at a speed of 50 kilometers per hour, and less. When stopping, it is desirable to cool the box;
• it is forbidden to start the engine while towing.

It should be noted that the torque converter is a substitute for the conventional clutch in cars with a manual gearbox. That is why in a car with an "automatic" instead of the usual three pedals, there are only brake and gas pedals. To move, just lock the shift lever to "drive" and press the gas pedal.

What is the main difference between an automatic transmission and a manual transmission?

In the previous article, we looked at how a mechanical gearbox works and found out that gear changes occur when a certain gear is connected, and there are several sets of them. The automatic transmission uses only one set of gears for gear shifting in its work, and the planetary gear allows this to be done.

The planetary gear is small in size - like an average melon, but it is responsible for transmitting all possible gear ratios, and all other parts in the automatic transmission only help it successfully cope with this difficult task. Structurally, it includes sun gears, followed by satellites and ring gear. They can be fixed in a certain position, working on the input or output - thereby, the gear ratio is determined.

The planetary gear uses locking some elements and unlocking others to shift gears and consists of only one central shaft, while the manual transmission uses gears and parallel shafts that interlock with each other - this is the advantage of the planetary gear and automatic transmission in general.

Brake band and clutches

Thanks to the brake band and friction clutches, certain elements of the planetary gear set can be blocked - and this makes it possible to switch various gears. The brake band blocks the elements of the planetary gear on the body of the automatic transmission (it is attached to the body), and the friction clutches allow you to block the components of the planetary gear set between themselves, preventing the rotation of the blocked elements counterclockwise. The brake band has a fairly high holding capacity and blocks the elements of the planetary gear set due to the self-compression effect.

Torque converter: torsional vibration damper that absorbs strong shocks

The torque converter has a turbine and a pump in its design. Between these bladed machines there is a reactor (outwardly it looks like a wheel with blades), which is a guide vane. It can be easily blocked by a freewheel or simply rotate, it all depends on the driving conditions.

The blades of the centrifugal pump throw oil onto the turbine wheel, the flows of which, in fact, transmit torque from the internal combustion engine to the automatic transmission. In order for the oil to circulate continuously, special gaps are provided between the turbine and the pump, and a certain geometry is attached to their blades even in production. It is the fact that the torque is transmitted by oil flows that explains the lack of a rigid connection between the gearbox itself and the engine (in mechanics, the input shaft is connected directly to the engine). Thanks to this scheme, it is possible to stop the car without turning off the engine.

However, we said earlier that simply transferring torque to the drive wheels is not enough, it is also necessary to change it qualitatively - the reactor copes with this task. Since it is located between the turbine and the pump, its vanes are placed in the path of oil return from the turbine to the pump. If the rector is stationary, then the speed of the oil circulating between the wheels increases. And the greater the speed of the circulating oil, the greater the effect it has on the turbine wheel. The reactor begins to rotate at the moment when the pump speed and turbine speed begin to compare, thereby reducing the kinetic energy of the working fluid. This mode of operation of the reactor is commonly called the "fluid coupling mode".

Sometimes it is simply not necessary to convert the speed and torque (let's say you are driving in a straight line at a constant speed), then the torque converter is blocked by the clutch. But as soon as the driving conditions change (we switched from a constant speed in a straight line to an uphill), the torque converter immediately starts working. When the turbine speed decreases, the reactor will begin to slow down, as a result of which the circulating oil will pick up speed and automatically increase the torque that is transmitted to the wheels (that is, to the shaft from the turbine). This range of increase is enough to overcome the slope without the need to shift to a lower gear.

How is transmission enabled?

Gear shifting occurs without a break in power - one turned off, the other immediately turns on. The hydraulic tappet is driven by the pressure of the oil used in the torque converter, after which it presses on the clutch. The pressure indicator is electronically regulated. At this point, the clutch elements (rigidly connected to the shaft) will stall. The shaft stops and the gear is engaged.

When the automatic transmission lever is switched to the “drive” mode, torque from the engine is transmitted to the central shaft. The shaft is connected to the sun gear while the ring gear is locked by a clutch. Once the ring gear is unlocked, it will gain its power as it rotates and the gear will upshift. If the electronic device received a command to downshift, then the shaft is fixed by the friction clutch, while the engine rotates the sun gear of the planetary gear set. At this point, the ring gear loses its power and the gear is downshifted.

For a visual demonstration of the automatic transmission device, we also suggest watching a video from Toyota.

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:

1. centrifugal pump;
2. stator;
3. centripetal turbine;
4. pump wheel;
5. 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.

Both in real life and in the virtual space, there is an eternal dispute between the owners of cars with automatic and manual transmissions. This dispute is also endless, like the one that is primary: an egg or a chicken. Without entering into it, we will simply try to fill in certain gaps in the knowledge of those novice car owners who have an automatic transmission installed.

What is it, automatic transmission?

We hear such types of automatic transmissions as tiptronic and steptronic. A few words about these common names.

Tiptronic- This is an automatic transmission with the ability to manually shift gears. In manual mode, the driver selects a gear manually by pushing the selector lever in the "+" or "-" direction.

Steptronic- Automatic transmission used in BMW. It also has the ability to manually shift gears, but the shift speed is increased, and is comparable to a manual transmission. In steptronics, the lever moves in positions P, R, N, and D. In addition, there is an “M / S” (Manual / Sport) position, which in the “sport” mode holds the gear until the maximum number of revolutions is reached, then the gear is upshifted .

How does an automatic transmission work?

Automatic hydromechanical transmission in the classic version consists of planetary gears, torque converter, overrunning and friction clutches, connecting drums and shafts.

Without going into the jungle, all the more it is strongly not recommended to do it yourself, the principle of operation of an automatic transmission is different in that gear shifting occurs due to the interaction of planetary mechanisms and a hydromechanical drive using electronic actuators.

Features of the operation of the automatic transmission have already been covered on the pages of the site. But we will repeat.

• A box - an automatic machine before starting to move requires careful warming up, especially in winter.
• It is not recommended to move the selector lever to the P and R positions while driving.
• There is no need to turn on neutral when descending a mountain, there will be no fuel economy (as it is believed), but braking problems may arise.
• Engine braking is not available in all modes. For more details on operation in various modes, the manufacturer provides instructions in the Manual. For all our carelessness, it is advisable to adhere to these instructions. First of all, this is, and secondly, not the last, this is the cost of repairing or completely replacing a delicate and sensitive unit - automatic transmission

Well, actually, you can start, warm up and start moving.

Good luck to you car lovers.