The automatic transmission of a car is designed to transfer engine power to the wheels. It selects exactly the gear that is best suited for the current speed. The automatic transmission eliminates the need for the driver to change gear manually. The car's computer uses sensors to determine at what point it is necessary to switch speed and sends a signal to in electronic format to turn the transmission on or off.
The main elements of an automatic transmission
Mechanism automatic box A car's gears are a system of levers and gears that transfer power to the drive wheels, allowing the engine to run at its most efficient.
The box is assembled in an aluminum casing, called the crankcase. It contains the main components automatic transmission:
- A torque converter that acts as a clutch, but does not require the driver to directly control it.
- planetary gear changing gear ratio when switching.
- Rear, front clutches, brake band, directly shifting gears.
- Control device.
How does a torque converter work?
The torque converter consists of the following main elements:
- pump or pump wheel;
- turbine wheel;
- blocking plates;
- stator;
- overrunning clutch.
To understand how an automatic transmission works, you need to understand its structure as a whole. So, the pump is mechanically connected to the engine. The turbine wheel is connected to the gearbox shaft using splines. When the impeller rotates while the engine is running, an oil flow is created that rotates turbine wheel torque converter.
In this case, the torque converter acts as a conventional fluid coupling, only transferring torque from the engine to the shaft of the automatic transmission through the liquid. With an increase in engine speed, there is no significant increase in torque.
To convert torque, the automatic transmission circuit includes a stator. The principle of operation is that it redirects the flow of oil back to the pump impeller, causing it to rotate faster, increasing torque. The lower the speed of rotation of the turbine wheel relative to the pump, the more residual energy is transferred by the stator through the returned oil to the pump. Accordingly, the torque increases.
Fundamentals of operation of the turbine and automatic transmission pump
The turbine always rotates slower than the pump. The maximum ratio of pump and turbine rotation speeds is achieved at stationary car, decreasing as the speed of the vehicle (V) increases. The stator is connected to the torque converter through an overrunning clutch that can rotate in only one direction.
Turbine and stator blades are specially shaped to redirect oil flow to reverse side stator blades. In this case, the stator jams and, remaining motionless, it transfers the greatest oil energy to the pump inlet.
Due to this mode of operation of the torque converter, maximum torque transmission is ensured. It increases almost three times when starting the car from a place.
When the vehicle accelerates, the turbine slips less and less relative to the pump until the moment comes when the stator wheel is picked up by the oil flow, starting to rotate in the direction freewheel overrunning clutch. At the same time, the device starts to work like a conventional fluid coupling, does not increase the torque. In this mode, the efficiency of the torque converter does not exceed 85%. This mode of operation is accompanied by the release of excess heat and an increase in fuel consumption.
Purpose of the blocking plate
This drawback is eliminated with the help of a special device - a blocking plate. Despite the mechanical connection with the turbine, it is structurally designed in such a way that it can move to the right and left. This device is activated when the vehicle reaches high speed. On command, the control device changes the oil flow so that it presses blocking plate to the torque converter housing on the right.
In this case, the turbine and the pump are mechanically connected to each other. To improve grip on inside a special friction layer is applied to the body of the torque converter. Thus, the engine is connected to the output shaft of the automatic transmission. Naturally, such a lock is immediately turned off even with slight braking of the car.
Only one of the methods for blocking the torque converter has been described above. However, any other method pursues the same goal - to prevent the turbine from slipping in relation to the pump wheel. The commonly described mode of action in various sources is called Lock-Up.
It will be easier to understand the operation of a torque converter for dummies if, instead of a turbine and a pump, we imagine two simple fans, one of which is powered by the network, and the other rotates due to the air flow created by the first fan. Only instead of air, oil acts here, and the blades of the first fan (pump in the case of automatic transmission) are driven not by electricity, but by mechanical connection with the car engine shaft.
planetary gears
The torque converter can increase torque, but only up to a certain limit. The automatic transmission device for a more significant increase in torque, for example, when overcoming slopes, as well as for reversing, provides for planetary gear sets. planetary gear also ensures smooth shifting while driving without loss of engine power. Thanks to her, the shifting occurs without the shocks that occur during the operation of a conventional transmission.
The planetary gear set includes the following elements:
- sun gear;
- satellites;
- epicycle;
- carrier.
The planetary gear is called because the friction wheels, rotating simultaneously around their axes and moving along with these axes, are very reminiscent of the planets of the solar system. It depends on their mutual position which this moment transmission is enabled.
How do you shift gears in an automatic transmission?
Gear shifting or a change in the gear ratio in the planetary gearbox is carried out by blocking and unlocking the elements of the planetary gear set using brake bands and friction clutches. In the hydraulic system of an automatic transmission of a car, gear shifting is carried out directly by a valve. A three-speed box has two such valves, one of which switches from first gear to second, the other from second to third. A four-speed box already has three valves.
Other types of automatic transmission
In addition to the considered hydraulic transmission other types of automatic transmissions are widespread today:
- CVT automatic transmission. In this type of transmission, there is no fixed ratio for the gears. Therefore, such an automatic transmission is called stepless. The principle of operation is that, unlike other "machines", it uses engine power more efficiently. As a result, cars equipped with this type of transmission are more economical and comfortable.
- Robotic checkpoint. Such a box can be conditionally called automatic, since in fact it is the usual “mechanics”, where the function of the clutch pedal is assigned to the electronic unit. Cars with which gearboxes are also quite economical, but less comfortable, since gear shifting in automatic mode is often accompanied by jerks.
Thus, in addition to the most common hydraulic automatic transmission There are several more types of automatic transmissions that differ in their design. They differ in price, economy, driving comfort. The general thing is that the driver is relieved of the need self-selection and gear shifting.
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 mean ( English letters) and numbers on the automatic transmission panel with gear shift knob. 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". Auto mode(practically, the same as the "D" mode).
- "L"- "low" (low). Mode low gear.
- "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 simulates mechanical mode switching from manual transmission, only in a simpler version.
- "S"- "sport". Sports mode movement.
- "OD"- Overdrive. Upshift (fast mode).
- W- "winter". Driving mode for winter period, at which starting off starts from the 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).
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 in four-wheel drive vehicle the designations "1" and "L" are present, 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 close to each other in parking lots and in streams. After all, even experienced drivers sometimes they forget to “take the car off speed” before starting the engine, as a result of which, when starting the car, it immediately starts to go and crashes into nearest car or an 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.
Most drivers who switch from "mechanics" to "automatic" at first automatically perform actions that they are accustomed to repeatedly perform when driving a car with mechanical box gears. 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 you need to stop in a traffic jam, at a traffic light or pedestrian crossing, then, of course, 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.
To prevent damage to the engine when going into 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 automatic transmission. In traffic jams frequent stops you need to use the "D" mode together 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 high speed), as the engine may stall, as a result of which the power steering and brake boost will be turned 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 acts destructively on the automatic transmission mechanism, and with such frequent use 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, the "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":
Thanks to design feature the automatic transmission provides, with the help of automation, the choice of the gear necessary for the movement of the car, without the participation of the driver in this process. At the same time, unlike a manual gearbox, the driver’s right hand is freed from gear shifting movements and there is no need to equip the car with a clutch pedal, which also excludes the driver’s foot movement to depress the clutch from the vehicle control process.
To start the movement of a car equipped with automatic transmission, the driver just needs to move the gearbox lever to the desired position and then all that remains is to adjust the speed with the gas and brake pedals. It is much easier to drive a vehicle equipped with an automatic transmission, which gives the driver a greater opportunity to focus on road conditions.
Regardless of the type, any transmission, whether manual or automatic, performs the same functions in a car - efficient use of engine torque, but different ways based on their design features.
Automatic transmission device
The functioning of an automatic transmission is based on the work of its planetary mechanisms and hydromechanical drive. In a small range of engine speeds, the automatic transmission allows the car to move in a wide range of speeds. Back to main elements automatic transmission devices include the following mechanisms:
- torque converter;
- planetary reductor;
- clutch packs;
- brake band;
- control device.
The main components and the principle of operation of the automatic transmission
The basis operating principle of automatic transmission the property of a fluid to transfer energy during rotation is assumed. This property made it possible to create a device (fluid coupling, torque converter), in which there is no rigid connection between the input and output shafts, and the mechanical energy between these shafts is transmitted using a flow working fluid.
The torque converter in an automatic transmission performs the function of automatically transferring torque from the power unit to the main components of the gearbox, which corresponds to the function of the clutch assembly in a manual gearbox. After reaching a certain engine speed, using the pressure of the working fluid on the torque converter units - the pump wheel, which is rigidly connected to the crankshaft of the power unit and the turbine wheel, interconnected with the main shaft of the gearbox, torque is transmitted. During a decrease in the speed of the power unit, the fluid pressure on the turbine wheel drops, and it stops. Accordingly, the clutch of the engine with the box is interrupted.
Due to the fact that the torque converter is limited in its ability to transmit mechanical energy in a wide range, it is connected to planetary multi-stage gears that provide gear shifting and reverse rotation.
According to its design, the planetary gearbox is a gear rotating around the central - "sun" gear. It functions by blocking and separating certain elements of the planetary series. A three-speed automatic transmission uses two planetary gears, and a four-speed automatic transmission uses three.
Friction packs or clutch systems are mechanisms that block moving elements planetary gear between themselves. According to its design, this is a set of several movable and fixed rings, which are blocked under the influence of a hydraulic pusher, which ensures the appropriate gear is switched.
The brake band also takes part in gear shifting, which temporarily blocks necessary elements planetary gear. The principle of its operation is the self-clamping effect used to block these elements. Having a relatively small size, the brake band softens the impacts of the mechanisms at the time of their operation.
The control device is designed to regulate the functioning of the brake band and the operation of the clutches. It consists of a valve block with spools, springs, a system of channels and other elements. The control device performs the function of shifting gears based on the specific driving conditions of the vehicle - when accelerating, it engages a higher gear, and when braking, it lowers.
Automatic transmission operating modes
Automatic transmission can operate in several standard modes. All of them are denoted by symbols developed in the last century in Latin: P, D, N, R.
Parking mode "P" or parking– ensures that all gears are turned off. In this case, the drive wheels are blocked by the gearbox mechanisms, and it is disconnected from the engine. In this mode, the engine is started.
Video about warming up the automatic box:
Driving mode "D" or drive– provides automatic switching gears while the vehicle is moving forward.
Mode "N" or neutral gear - provides disengagement of the driving wheels of the car from the gearbox. This mode is used during short stops or when the vehicle needs to be towed.
Reverse mode "R"- Provides reverse vehicle movement.
The driver's control of the automatic transmission must be carried out in the prescribed sequence: 1. Parking; 2. Reverse; 3. Neutral; 4. Movement.
In modern automatic transmissions for comfortable ride additional modes of operation are provided.
Mode low gear "L"- used during slow movement in difficult traffic conditions. In this mode, the gearbox operates only in the selected gear, regardless of changes in engine speed.
Modes "2" And "3"- are used when towing a load by a vehicle or in appropriate conditions. The numbers indicate the number of fixed gears in which the car is moving.
Overdrive mode "O/D" or "Overdrive"- used for frequent automatic upshifting. This mode provides more economical and uniform motion car, mainly on highways.
Urban traffic mode "D3"- limits the automatic shifting of the box to third gear.
Balanced motion mode Norm- allows the box to go to overdrive upon reaching the average values of rotation crankshaft engine.
Mode winter traffic "S" or Snow(may also be denoted by the symbol "W" or "Winter") - allows the car to start moving from second gear, thereby preventing slipping of the drive wheels. Also, while driving, the operation of the automatic transmission is performed more smoothly using low speed engine.
Engines internal combustion unable to keep the vehicle moving different modes without special devices that change the speed of the crankshaft. Into parts Vehicle automatic transmissions are used for this. The use of automatic transmissions reduces the number of vehicle controls and simplifies driving.
Historically, the term automatic transmission (changes) of gears has been firmly entrenched in only one type of device. We are talking about a planetary mechanism with a torque converter that has become widespread. Such a device can be called a classic.
Recently there have been quite a few a large number of cars with automated, or rather, robotic control mechanical transmissions. General device Automatic transmission and the principle of its operation differs significantly from these devices.
From a purely technical point of view, any gearbox can be considered automatic, the operation of which does not require the intervention of the driver.
The only exceptions are CVTs, in which the change in the number of revolutions occurs steplessly (there are no fixed gears), and therefore smoothly and without the slightest jerks. Therefore, CVTs cannot be attributed to gearboxes.
In order to finally understand the terminology, it should be noted that it is customary for automatic transmission engineers to call only planetary part unit. It is in this mechanism that the gear ratio of the rotational speed changes input shaft. Together with the torque converter, this mechanism forms an automatic transmission.
History of creation
The history of the appearance of the automatic transmission in its classic form begins at the dawn of the automotive industry. Its three main elements were created and used in different car designs, and only with the advent of microprocessors were they combined in one device.
The first two-stage planetary boxes were used back in the twenties of the last century on. The second element - servos in the control system of the box appeared a decade later. First semi-automatic boxes began to be used on cars produced companies General Motors and Reo.
A truly workable automatic transmission was made only with the advent of a hydraulic clutch, and later a torque converter. They were used on cars American company Chrysler.
The combination of all three elements allowed the engineers to solve all the problems associated with the automatic transmission of torque from the engine to the wheels of the vehicle.
Thus, technical progress and led to the appearance of the first serial Buick cars equipped with a Dynaflow two-speed automatic transmission. This was already a significant step forward, making up for the significant power losses of earlier devices.
Subsequently, the number of steps only increased, for example, by Land Rover Evoque was fitted with a 9-band automatic.
Automatic transmission - what is it
classical automatic transmission is a rather complex complex of two devices. Answer the question: "What is automatic transmission?" possible only by understanding its design.
Automatic transmission consists of three main parts:
- A torque converter that receives torque from the power unit and transmits it to the mechanism immediately following it.
- Actually planetary type gearboxes - this device converts the force and drives the wheels through the main gearbox.
- A control device consisting of a number of spools that regulates the flow of oil to the actuators.
By analogy with manual transmission The automatic transmission torque converter plays the role of a clutch - it is installed between the engine and the planetary gear. Its device is much more complex and allows transmission slippage during the start of movement and braking. On most modern automatic transmissions, the torque converter locks up when high revs engine.
Toyota's video explains the principle of operation of the torque converter and other automatic transmission elements:
The planetary box corresponds in purpose to its mechanical counterpart. The difference lies in the fact that in the automatic switch are made by servo drives, and on the mechanics - manually.
In fact, the automatic transmission is controlled by two pedals: an accelerator and a brake. In this case, pressing the "gas" does not increase the engine speed, but directly affects the speed.
Arrangement of units and mechanisms
Constructions individual elements may differ. Consider only one of the most common options - a torque converter. It contains:
- turbopump;
- turbine;
- stator.
Frame this device It is rigidly mounted on the flywheel, which by analogy is similar to a mechanical clutch basket.
Stators are of two types: fixed in relation to the engine block or locked with a band brake. This design allows optimal use of torque, especially at low speeds. The torque converter housing is filled with viscous oil.
A planetary gearbox or gearbox is a whole set of mechanisms, it includes:
- epicycle - a large gear with teeth turned inward;
- small sun gear;
- carrier with satellite gears.
Video - the principle of operation of the planetary gear set of an automatic transmission:
One of the above nodes is fixed motionless with respect to the box crankcase. The satellites are simultaneously engaged in both the epicycle and the small sun gear. In addition to the above nodes, the box includes friction clutches, which, in turn, consist of two elements: a hub - a hub and a drum.
Between them is a set of alternating steel and plastic friction discs and an annular piston that controls their operation. The planetary gearbox also has an overrunning clutch, its design may be different. It is designed in such a way that it is able to rotate quite freely in one direction and jams when changing direction.
The automatic transmission device, in addition to the nodes mentioned above, also has a control mechanism, the principle of operation of which depends on the type of actuators.
In modern automatic transmissions, hydraulic actuator spools move under the influence of solenoids, which are energized by an electronic control unit. In the classic version, control is carried out taking into account the position of the accelerator pedal and the centrifugal type oil pressure regulator mounted on the output shaft of the box.
The driver chooses the mode AKP work using a selector, in most modern cars it is mounted on the center console. Management can be duplicated by buttons on the steering wheel.
Currently, a single standard for designating automatic transmission modes has been adopted, which allows the driver not to retrain when changing cars from different manufacturers.
The principle of operation of an automatic transmission (automatic transmission)
There are several types of automatic transmissions, each of which has a number of features.
IN general view The principle of operation of a modern automatic transmission is to transfer torque from the engine crankshaft to the transmission mechanisms. In this case, the gear ratio changes depending on the position of the selector and accelerator and the driving conditions of the car.
Consider the principle of operation of the automatic transmission in more detail:
- The engine spins the flywheel, on which the drive turbine is rigidly fixed. It causes a whirlwind operating fluid in the crankcase, which, due to viscosity and friction, drives the driven turbine. The absence of a rigid mechanical connection makes it possible to rotate them at different frequencies. At high speed the torque converter locks up to reduce energy loss.
- The force is transferred to input shaft Automatic transmission, where the gear ratio changes through a system of gears. Friction clutches allow you to use the necessary sections to ensure optimal mode engine operation. To reduce shock loads and jerks, overrunning clutches are used in the machine, which tend to slip on reverse.
- Friction control is carried out using hydraulic system, consisting of an annular executive cylinder. The hydraulic drive compresses a certain package of friction clutches, which actuate a section of gears connected to them.
- The oil pressure in the system is provided by a special hydraulic pump. Hydraulic drives are controlled by spools, the movement of which in modern boxes is provided by solenoids. In the classical automatic transmission they have hydraulic drive. In this version, the control is carried out directly by the accelerator and the centrifugal pressure regulator.
Gear shifting in modern automatic transmissions is carried out using a selector or buttons mounted on the steering wheel spoke. The driver selects the operating mode of the box, in electronic unit control, the corresponding program is activated. Solenoids open right valves, and there is a transfer of torque from the engine to the transmission of the car. As necessary, stages with the optimal gear ratio are connected.
Video - the device and operation of an automatic transmission:
One of the most important specifications Automatic transmission is shifting time. For cars of different classes, this parameter has its own values, while the difference between them can be significant.
Yes for most mass car the response time is in the range from 130 to 150 ms. Supercars can boast a three times lower rate of about 50 - 60 ms, for fireballs it is even less - 25 ms.
Modes
The following are currently standard:
- P (parking)- parking mode power unit and transmission are disconnected, the selector is locked. The parking brake is used in the same way as on machines with a manual transmission.
- R (reverse)- reverse mode, the selector cannot be moved to this position when the car is moving forward.
- N (Neutral)- on Soviet cars denoted by the Russian letter "H", the mode is designed for stops for a period of not more than five minutes or for towing over relatively short distances.
- D (Drive)- on domestic cars"D" forward movement, while all stages are actuated in turn, with the exception of the step-up section.
- L (Low)- forced downshift is designed to ensure the movement of the car in heavy road conditions and in traffic jams at low speed.
In addition to the above, there are additional automatic transmission modes:
- O/D (overdrive) the mode in which it is possible to turn on a stage with a gear ratio of less than one is designed for driving on a highway at a constant speed.
- D3 or O/D OFF involves the use of only low gears without overdrive allows you to avoid frequent blocking of the automatic transmission torque converter.
- S (other version number 2) winter mode for driving in difficult road conditions in 1st and 2nd gear or in second.
- L (another option is number 1) another range, when only the first stage is used for moving in parking lots, entering and leaving the garage.
The automatic transmission does not support engine braking in all modes, which must be taken into account when operating the car. The use of a freewheel allows the vehicle to coast.
In most machines, engine braking is only possible when the low range is engaged from the P position, the transition is not possible while driving.
Push-button control systems located on the steering wheel spoke usually introduce a number of additional automatic transmission modes:
- power or Sport provides better dynamics acceleration of the car, with the advent of electronic controllers, it can be turned on by sharply pressing the accelerator.
- Snow or Winter to avoid wheel slippage, the start of movement is carried out from second or even third gear.
- shift lock or Shift lock release allows you to unlock the selector when the power unit is turned off.
Auto-activated sports mode is also called kickdown, in most models, its use is possible only on overdrive. To eliminate driver errors when switching the selector, its lever is blocked different ways. This may be a special button on the lever and the need to drown it down to move from one position to another.
In the event of a breakdown of the transmission mechanisms or a danger to them, the automatic transmission goes into emergency mode, the question arises - what is it? In fact, in the event of such a malfunction, the driver has the opportunity to get to the garage or car service on his own.
Advantages and disadvantages
Like any complex device, automatic transmission has a number of advantages and disadvantages. What are the pros and cons of an automatic transmission?
Let's start with the benefits:
- The driver is not distracted by manipulating the manual transmission, mode selection can be made at the beginning of the trip. This, of course, improves traffic safety.
- The presence of a torque converter provides more comfortable conditions ride without jerks. This has a positive effect on the condition of the transmission elements and engine parts.
- High reliability of modern boxes and no need for after-sales service the entire period of service.
The disadvantages of such boxes include lower efficiency, which leads to
Now, for sure, there are very few opponents of the assertion that automatic transmissions are being forced out of the market at a fairly rapid pace. manual gearboxes. By the way, do you know what is the difference between ? But, despite the fact that the vast majority of drivers choose a car with an automatic transmission, only a small part of them use the “automatic” correctly, which can lead to a significant decrease in efficiency or, much worse, a breakdown of the unit.
Using the automatic transmission is very simple and convenient.
And, in addition to basic knowledge that the automatic transmission automatically selects gear ratio, most suitable conditions movement, and thus endows the ride with convenience, every driver should know the basic principles correct use such a unit, so as not to shorten its service life.
Automatic transmission - how to use
First of all, you should understand how the modes are switched in an automatic transmission.
Automatic transmission switching and control modes
The automatic transmission control is as follows.
Parking (letter P on the selector) - designed to start the engine. Switching to position P is made after a complete stop and putting the car on the "handbrake";
Moving forward (D) - the standard automatic transmission mode, used more often than others;
Reverse (reverse, position R) - the car can only move backward. Switching while stopped with the brake pedal depressed;
"Neutral" (N) - the mode when the engine and automatic transmission are completely open. Most often used to warm up the engine on idling in cold weather;
D3 (S) - Low gear modes: switches on descents or ascents. The car brakes more with the engine;
D2 - designed for difficult conditions(slippery surface, mountain road, etc.). Movement is possible in first and second gear. Driving in third and fourth gear is prohibited.
D1 on Japanese cars designated as L - movement is possible only in first gear. Mainly used for engine braking steep descents, driving on a dirty, swampy or icy road, where you need to move "retracted", without re-gassing.
Additional modes of automatic transmission
In addition, more modern boxes machines are equipped with all big amount additional operation algorithms: normal or normal (N), economical (E), sport mode (S) and others. There is a mode, this mode is discussed in a separate article.
Basic rules for using the machine box
First of all, you should remember that automatic boxes do not like sharp accelerations and prolonged slippage of the wheels - this leads to their overheating of the “automatic machines”. If it is impossible to move in any direction, you should not feverishly move the link in the selector groove, but it is better to seek outside help and push or tow the car. General Process driving a car and using an automatic transmission is as follows. To start using the automatic transmission you need:
- drown the brake pedal, the selector switches from position P, N or R to position D;
- car is removed from hand brake;
- after a smooth release of the brake pedal, the car will gradually and smoothly begin to move forward;
- to increase speed, you should use the accelerator more, which will be accompanied by an increase in gears; - to reduce speed, it is enough to relieve pressure or completely release the gas pedal. Gears will change already in the downward direction;
- if you want a more significant slowdown or stop, you must apply the brake, and during the resumption of movement, it is enough to resort to the gas pedal again;
- it is important to remember that with such a driving rhythm, the gearbox must always be in “drive” (position D), which is advisable to change only during a long stop.
Additional algorithms for automatic transmission
Winter mode "automatic" Depending on the manufacturer, it may have different markings: Winter, icon * , Snow, W and so on. Main purpose winter regime is to minimize slippage, for which the activation of the first gear is excluded. To start, the second stage is used, which allows you to more smoothly transfer torque to the wheels, which is very important on slippery surface. Any gear change takes place at low engine speeds, thereby ensuring the smooth operation of the gearbox and almost completely eliminating the possibility of skidding. At a warm ambient temperature, it is strictly forbidden to activate this algorithm.
It is strictly forbidden to move the gearshift lever to the “P” and “R” positions. To move the lever to this position, you need to stop. Otherwise, you can disable the automatic transmission. It is also not recommended to move the lever to the “N” position while driving, this can cause a skid, especially on an icy road. You can move the gearshift lever to all other positions while driving. It is also recommended to move the lever to the "N" position during long stops with the engine running, for example, in traffic jams or traffic lights. This is especially true in summer, when high temperatures, as it will help to avoid overheating of the "machine".
Video: How to use an automatic transmission
Features when driving a car with automatic transmission
Firstly, it should be clearly remembered that not a single automatic transmission “likes” to work unheated, especially with increased load. It is for this reason that even at warm ambient temperatures, the first few kilometers after a long parking should be driven at low speed and without vigorous acceleration in order to warm up the oil in the transmission. Also important is the fact that the gearbox needs a little more time to reach operating temperature than the engine. For fastest warm-up automatic box in cold weather it is possible to change the operating modes several times while standing still, to stand with the D mode activated (holding the brake) or to activate the winter mode for a short time at the beginning of the movement.
second moment should follow the roads good coverage. Since modern gearboxes, even mechanical ones, do not differ in love for off-road. Exception - special vehicles adapted to similar conditions. Also, automatic transmissions do not respond well to towing heavy trailers or other vehicles. In such situations, they are subject to rapid overheating, which greatly accelerates wear. In addition, avoid towing the "automatic" car itself. Some exceptions may be reflected in the instructions for the car, but they rarely go beyond the limits of a distance of 50 km and a speed of more than 50 km / h.
Does an automatic car need a handbrake?
Absolutely all cars are equipped with a parking brake. Only the mechanisms of its implementation differ: mechanical, electromechanical or completely electronic. However, despite this, the vast majority of owners of cars with automatic transmission neglect its use, citing the fact that it is enough to put the car in “parking”, and with a short stop, a service brake is enough. But, unfortunately, this approach is not correct. Since even the manufacturer's instructions prescribe permanent use hand brake when long-term parking. Most likely, such a precaution is caused by a banal reinsurance automotive companies which, to be fair, can hardly be called redundant. Moreover, there are many situations in which it is impossible to do without a "handbrake":
- it must be activated when stopping or leaving the car with the engine running;
- a hand brake will be indispensable as insurance when changing a wheel or carrying out similar manipulations;
- in case of an unplanned stop on a descent or ascent, the automatic transmission selector will require undue force when transferred to P if it is not tightened parking brake. IN similar situation, at the beginning of the movement, the handbrake should be loosened only after the selector has been transferred from “parking” to “drive”. work and maximize the pleasure of a comfortable ride. Well, the main argument will be the guaranteed achievement of the specified service life of the machine box.
Video: How to drive an automatic car. Management principles
