In this article, we will consider questions and answers on the operation of an automatic transmission. What is overdrive and kickdown, how to use automatic transmission?
What do position symbols mean?
The range select lever (RVD) has several positions, which have an alphabetic and numeric designation. The number of these positions for different models of cars is different, but on all cars, the high pressure hose must have positions marked with the letters "P", "R" and "N".Position "P"- It is selected when the car is parked for a long time. In this position, all controls are turned off in the automatic transmission, and its output shaft is blocked, so movement is impossible. This mode allows the engine to start.
Position "R"- Reverse. Moving the lever to the "R" position while driving can damage the transmission. In this position of the RVD, starting the motor is not possible.
Position "N"- in the transmission, all controls are turned off or only one is turned on. The output shaft lock mechanism is disabled, i.e. the car can move freely. This mode allows the engine to start.
For vehicles equipped with four-speed transmissions, the range hose has four forward travel positions: "D", "3", "2" and "1" ("L"). If the lever is set to one of these positions, the engine cannot be started.
"D" range- main mode. It provides automatic shifting from first to fourth gear. Under normal driving conditions, it is used.
Range "3"- movement is allowed at the first three speeds. It is recommended to use when driving in conditions of frequent stops.
Range "2"- Movement is allowed only in first and second gears. Used on mountain roads. Switching to third and fourth gears is prohibited.
Range "1"- Movement is allowed only in first gear. Allows you to maximize the engine braking mode. For example, when driving on steep slopes.
On some cars, permission to use the fourth, overdrive, gear is carried out using a special "OD" button. If it is in the recessed position and the lever is in the "D" position, then upshifting is allowed. Otherwise, the inclusion of the fourth overdrive is prohibited. The state of the system in this case is reflected by the indicator "O/D OFF".
Overdrive means overdrive. Designated as "OD", either D or D in a circle. Overdrive is used for economical driving on the highway.
What is the economy, sport and winter mode for?
Most automatic transmission vehicles have several options for shift control. These include - economical, sports, winter.economic program. The program is tuned to ensure movement with minimal fuel consumption. The movement is smooth and calm.
Sport program. The program is set to maximize the use of engine power. The car develops, in comparison with the economical program, significantly greater accelerations.
To implement an economical or sports program, a special button or switch is located on the dashboard or next to the lever, which may be labeled "POWER", "S", "SPORT", "AUTO".
Electronic control units have a special program for starting off on a slippery road ( winter program). To activate it, there is a special button, which may be labeled "WINTER", "W", "*". In the case of its action, various automatic transmission operation algorithms are possible, but, as a rule, in all cases, starting is carried out either from the second or from the third gear.
Is it possible to switch the lever on the go?
It is possible, but not in all positions. It is strictly forbidden to move the lever to the “P” and “R” positions when moving forward. The lever can only be moved to both of these positions when the machine is at a complete stop. Violation of this rule may result in damage to the transmission.It is not recommended to move the lever to the “N” position while driving, as the connection between the wheels and the engine is lost and sudden braking can cause skidding. And in all other positions, you can safely translate. In some cases, it is recommended to do this on purpose. So moving the lever from position "3" to position "2" will increase the efficiency of engine braking.
Should the lever be moved to "N" when stopped? It makes sense only during long stops in traffic jams in hot weather, to reduce heat generation and prevent overheating of the oil in the box. In other cases, this is not necessary.
Do I need to use the parking brake if the lever is in "P"?
For reliable fixation of the machine on relatively flat areas, the automatic transmission output shaft locking mechanism is sufficient. If the car is on a slope, then the handbrake must be applied. Moreover, it is first necessary to tighten the hand brake and only then set the lever to the “P” position. So you release from the additional burden associated with the desire of the car to roll.How to tow a car with an "automatic"?
There is no single answer to the question of how to properly tow a car with an automatic transmission. Some cars have strict restrictions. Vehicles with a three-speed automatic transmission can be towed at a speed of 40 km/h for a distance of 25 km, and with a four-speed one at a speed of 72 km/h for a distance of up to 160 km.In case of a faulty transmission, a tow truck is preferable. The fact is that in the automatic gearbox, lubrication is carried out forcibly, i.e. oil is supplied to each friction pair under pressure. If the transmission is faulty, then there is no certainty that lubrication is present.
Carry out towing with the engine running and the lever in the "N" position.
Do I need to warm up the box before driving?
In the cold season, before the start of the movement, it does not hurt to warm up the oil a little. It is necessary to move the lever to all positions, lingering in each of them for a few seconds. Then turn on one of the ranges of movement, and hold the car for several minutes with the brake, while the engine should be idling.What are the main advantages and disadvantages?
A car with automatic transmission is equipped with a passive safety system that does not allow the engine to be started in positions other than "P" and "N". It also prevents spontaneous movement of the car when parked on uneven ground, tk. The key can only be removed from the ignition switch in the "P" position of the high pressure hose.
The disadvantages include lower efficiency than a manual transmission, which increases fuel consumption. But modern automatic transmissions in some driving modes can achieve higher efficiency compared to manual transmissions by maintaining optimal engine speeds and "intelligent" control of the torque converter lockup.
Another drawback is the worst dynamic acceleration performance of the car. The difference is not so great and for the majority of drivers is insignificant. Also, a car with automatic transmission cannot be started except with the help of a starter.
What is a kickdown?
If you press the gas pedal all the way while driving, the gearbox will shift down one or two gears. This mode is recommended for hard acceleration, which is useful when overtaking.
Reverse upshifting can only occur when the engine reaches maximum RPM. If you release the gas pedal, the gearbox will return to normal operation.
What are the methods for checking the condition of the automatic transmission?
First, check the oil level and its quality. Secondly, the time for switching on the gear when moving the lever from "N" to "D" or "R" should not significantly exceed 1 - 1.5 seconds. The inclusion of the transfer can be judged by a characteristic push. When switching, there should be no “shocks”, vibration and extraneous noise. The moment of switching should not be accompanied by an increase in engine speed. An experienced driver on the behavior of the car on the road can make a preliminary conclusion about the state of the automatic transmission.How is troubleshooting done?
The operation of "electronic" automatic transmissions is controlled by an on-board transmission computer, which can be made as a separate device or combined with a control unit. The transmission computer receives signals from various sensors located in the automatic transmission and outside it. It processes this information and, based on the analysis, issues commands to the actuators. Thus, the operation of the automatic transmission is controlled.The computer also performs another function - monitoring and diagnosing faults. For all input signals there are admissible limits of their change. If any signal is out of range, then the computer writes to memory a certain sequence of numbers - a code (Diagnostic Trouble Code - DTC) corresponding to this malfunction.
To read the codes in the computer's memory, special diagnostic equipment is required - a scanner. The scanner allows not only to read codes, but to erase them, and you can also determine the readings of various sensors. The procedure for reading and identifying faults by codes is often called computer diagnostics.
In the event of serious problems, the control system switches to automatic transmission protection mode. Emergency mode has different names: Limp In, Limp Home, Safe Mode. The operation algorithms of the control system in emergency mode are largely determined by the transmission model. In some cases, the system stops monitoring the quality of switches, and they occur with "bumps". In other cases, the box engages the second or third gear, and all gear changes are prohibited.
In some cars emergency mode is accompanied by flashing or permanent indication of one of the signals: "Hold", "S", "Check AT", "OD OFF". Also, the signal can be "Check Engine", or a symbol in the form of an engine outline. If none of these signals on the panel is lit, this does not mean that there are no trouble codes in the computer's memory. But if there is a signal, then there are codes in the computer's memory.
The emergency mode does not involve the operation of the machine, it only serves to get to the service and eliminate the malfunction. If this is not done, it may turn out that due to a minor malfunction that was not fixed in time, the entire box fails.
What are adaptive transmissions?
This term refers more to the control system, and not to the automatic transmission itself. The development of "electronic" transmissions has led to the emergence of adaptive gearboxes. The developed control algorithms become more intelligent, which leads to the emergence of new characteristics. The on-board computer monitors the driver's driving style, adapting accordingly to it.
In addition, the operation algorithm takes into account the wear of frictional controls. All this leads not only to an increase in the comfort of the trip, but also to an increase in its resource and efficiency.
What is Autostick or Tiptronic?
This is an automatic transmission control system, in which, along with automatic, a semi-automatic control mode is provided, in which the driver gives the command to shift gears, and the quality of these shifts is ensured by the control system.This mode has different names (Autostick, Tiptronic). In cars equipped with such a system, the lever has a special position in which the Autostick mode is activated. Regarding this position, there are two opposite, non-fixed positions of the automatic transmission lever. These positions are marked with "+" ("Up") and "-" ("Dn"), respectively, for upshifting or downshifting.
As a rule, often the cause of automatic transmission breakdowns is their illiterate maintenance and use. After starting the engine, in order for the automatic transmission to take on a working state, it is necessary to wait about a minute before starting to move. So let's move on to the topic of this article: driving with automatic transmission .
Automatic transmission control
P range (Park) - parking mode.
This mode is selected when the machine is parked for a long time. In this position, the controls are disabled in the box, the output shaft is blocked, as a result, the machine cannot move (the drive wheels are blocked, the blocking is not connected with the parking brake and is located inside the box itself). Starting the engine in this mode is allowed.
Do I need to use the parking brake while parking? On flat areas, subject to serviceability, blocking the output shaft of the box for reliable fixation is quite enough. When stopping on a slope, it is advisable to use the parking brake. In this case, first you need to pull the handbrake, and only then put the gearshift lever in P mode. In this way, you remove additional load from the mechanism for blocking the output shaft of the automatic transmission.
Range N (Neutral) - neutral mode.
In this mode, controls are disabled. At the same time, with the output shaft blocking mechanism turned off, the car can move freely. Starting the engine in this mode is also allowed. N mode is used when towing a car for short distances, as well as for short stops.Sometimes some drivers have a question:
Do I need to translate the automatic (automatic transmission) into N at a traffic light?
It makes sense to transfer the automatic transmission to neutral mode only during long stops in traffic jams in hot weather, in order to avoid overheating of the automatic transmission itself. In other cases, this is not necessary at all.
Range R (Reverse) - reverse mode.
An attempt to turn on the R mode while moving forward will inevitably lead to a breakdown of the automatic gearbox and other transmission elements (on vehicles that do not have a corresponding lock in the transmissions, it is strictly contraindicated to turn on the R mode until it comes to a complete stop). It is also impossible to start the engine if the gear lever is in this position.
Four-speed automatic transmissions for forward movement have four modes: D, 3, 2 and 1 (L). It should be noted here that starting the engine is not possible if one of the listed modes is enabled.
Range D (Drive) - the main mode for moving forward.
This mode performs automatic sequential gear shifting (in this mode, all gears are usually involved, with the exception of upshifts). This mode is recommended under normal driving conditions.
Range 3(Number 3 on some types of automatic transmissions) - the first three gears are engaged while driving. This mode is active, it is great for urban traffic, it turns off when the ignition is turned off. Especially at a high speed of the automatic gearbox, it will not work to save fuel, this mode does not allow the torque converter clutch to repeatedly lock-unlock in conditions of torn city driving (no more than 80 km.h.), It is also partially blocked by switching to higher gears. Most suitable for driving when frequent stops are inevitable and for driving on roads full of descents and ascents. Engine braking is possible in this mode.
Range 2(Number 2 on automatic transmission) - in this mode, only second and first gears are allowed. Most suitable for use in mountain winding roads. It is forbidden to switch to fourth and third gear.
Range 1(L or Low) - low gear. In this mode, movement is allowed only in first gear. The traction capabilities of the engine in this range are realized to the maximum, since the torque transmitted to the wheels only in first gear is maximum. Particularly effective engine braking in this mode. Driving on steep descents and ascents must be carried out in first gear.
Overdrive (O/D)
On some automatic transmissions, a mode is set in which automatic upshifting is possible. O/D button (Overdrive) used to connect this automatic transmission mode. Its recessed position when the mode (Drive) is on allows you to switch to a higher gear. If you release this button, then switching to the last gear will again become impossible. The O/D OFF indicator indicates the status of the control system. If the indicator is on, then the use of the Overdrive mode is impossible, otherwise it is possible.
It is recommended to use overdrive mainly on the highway for a more economical and measured movement. Interestingly, some four-speed automatic transmissions (for example, (toyota) aisin 241e) can disable 4th gear with a gear ratio of 1, which is not an overdrive either!
One of the differences between the automatic gearbox and the mechanics is the inability to produce engine braking in each mode. In overrunning clutches, in modes that do not allow engine braking, the transmission slips and the car moves “coasting”. And when driver position 1 is selected, engine braking is activated from first gear. In the first gear in position D, such braking is not possible.
How to start the movement of a car with automatic transmission?
As a rule, often the cause of automatic transmission breakdowns is their illiterate maintenance and use. After starting the engine, so that the automatic shift boxthe gear has taken on a working state, before starting to move, you must wait about a minute. Before starting to move without pressing the throttle pedal, it is necessary to depress and hold the brake pedal while putting the gearshift lever in D or R mode. After waiting for a slight push, you can start moving by releasing the brake pedal and stepping on the accelerator pedal with your foot. Dynamic driving for some time after the start of movement should be avoided so that the oil in all components and assemblies reaches its operating temperature. Before starting to move, for more efficient warming up of the automatic transmission, the gearshift control lever handle must be moved to different positions, lingering in each of them for some time. Then, turning on one of the driving modes and pressing the brake, hold the car in place for a couple of minutes, the engine should be running at this timein idle mode. At low ambient temperatures in position R, it is unacceptable to start moving without fully warming up the automatic gearbox, because this (due to the high viscosity of the fluid in the transmission) can damage the planetary mechanism.
automatic transmission how to use video
Towing a car with automatic transmission
A faulty car is towed in N mode, but do not forget that it is possible only for relatively short distances. Due to the fact that the oil pump is also idle in the idle engine, the lubrication of the components and elements of the automatic gearbox is significantly deteriorating. All of the above is relevant when transporting a car over long distances. Therefore, if it becomes necessary to transport your faulty vehicle with automatic transmission, you need to do this at a speed not exceeding 70 km.h. and at a distance of no more than 70 kilometers. Otherwise, it would be ideal to use a tow truck.
Is it possible to skid on an automatic transmission?
It is more difficult to stall on a car with an automatic transmission than on a car with a conventional “mechanics”. But if this nevertheless happened, then “rocking” the car by switching the gearbox from the forward position to the reverse gear position and vice versa is simply unacceptable. In this case, you need to use a lower range, it excludes shifting to higher gears, and in this mode, try to overcome the mud area using the brake as a clutch. In almost the same way (without re-gassing and playing along with the brake) they perform maneuvers in a limited space.
Is it possible to shift gears on the go?
Switching driving modes on the go is allowed, but not in all positions. So, for example, it is unacceptable to turn on the P and R modes when moving forward. The inclusion of these modes is carried out under the condition of a complete stop of the car. Neglect of this rule will inevitably lead to serious. It is also undesirable to put the gearshift lever in N mode while driving, because in this mode the connection between the engine and the wheels is disconnected and, in case of sudden braking, can lead to skidding of the car. You can switch to any other automatic transmission mode on the move. In some cases, this is even necessary. For example, switching from mode 3 to mode 2 improves engine braking performance.
Additional modes of automatic transmission
In later model automatic transmissions, where there are more operating ranges, there are additional modes of operation. In the control system of the automatic transmission, they are present in the form of pushbutton switches. An experienced driver knows how to use automatic transmission modes, so let's look at everything ourselves.
Economy mode("Eco" or "E") - provides the minimum fuel consumption while driving, as the engine is limited in the speed range at each stage. Thus, the joint work of the engine and the automatic transmission takes place in such a way that in each overdrive, the engine actually starts from idle, further increasing them, but not bringing them to the maximum. In this mode, the movement of the car is calm and smooth.
Sports mode("S") - in this mode of operation of the automatic transmission, engine power is used to the maximum. Each subsequent gear is engaged at frequencies close to the maximum torque. Accelerating further, the rotation of the crankshaft reaches its maximum, and thus the engine develops its full power and begins to work with full efficiency. And the car in this mode moves with much greater acceleration compared to the economy mode. A special switch designed to implement a sport or economy mode is usually located next to the gear lever and may have various designations, such as - POWER, S, SPORT, AUTO, A / T MODE, etc. Sports automatic transmissions have also become widespread, which have slightly different transmission control algorithms. In this case, switching between different operating modes can be done both with a selector and with the help of the corresponding function buttons, when the position of the automatic transmission lever remains unchanged.
kickdown- a mode that allows the engine management system and automatic transmission to achieve high acceleration values, for example, to overtake. The automatic transmission enters this mode after a sharp press on the accelerator pedal, switching to one or two downshifts. The torque transmitted from the engine to the wheels will increase, while the speed range in the engine is such that its return is almost maximum. And when the maximum engine speed is reached, the machine switches to the next overdrive. If the accelerator pedal is released, the automatic transmission will return to normal operation. Sometimes, when Overdrive is off, Kickdown is disabled. It is necessary to take into account the factor that on a slippery surface with a forced downshift, slipping of the drive wheels and further skidding are inevitable.
Winter mode(Snowflake) - to activate this mode, a special button or switch with the following designations is provided: Winter, W, Hold (or Snow). To avoid slipping of the drive wheels on a slippery road when starting off, the torque transmitted to the wheels from the engine is required to be minimal. This is done by starting the car from second or third gear - this is fraught with overheating of the automatic transmission, so driving constantly in this mode is contraindicated.
Emergency mode- this mode of operation of the automatic transmission is activated in case of malfunctions in the control system or transmission that can lead to. The control unit includes a transmission protection program and this allows the car to get to the car service on its own. As a rule, in emergency mode, shifts are prohibited and any one gear is working. The number of such a gear usually corresponds to the gear in which the shift solenoids are in the off state. Also, when triggered, the torque converter lock-up is prohibited and the maximum pressure in the main line is set.
Adaptive automatic transmission mode (automatic transmission) | Automatic transmission adaptation.
Adaptive gearboxes owe their appearance to the progress in the development of electronic automatic transmissions. Control algorithms become more intelligent, hence new qualities appear in the same transmissions from the point of view of mechanics. Now the on-board computer monitors the features and driving style of the driver and adjusts the operation of the automatic transmission and engine properly for them. With a smooth manner of movement, the computer, by means of appropriate amendments, does not bring the engine to maximum power rates of operation, which significantly reduces fuel consumption. If the driver prefers a sharp, “gusty” driving style, accompanied by frequent depressing of the accelerator pedal, the computer emphasizes frequent acceleration and intense speed and brings the engine to maximum speed. In order to make the most dynamic acceleration, the control system switches two, sometimes three steps lower. It is curious that the wear of the friction elements of an automatic transmission is already included in the operation algorithm. Which favorably affects not only the comfort of driving such a car, but also increases its efficiency and.
Automatic transmission mode AUTOSTICK (StepTronic, TipTronic)
Such an automatic transmission control system, in which both automatic and semi-automatic control modes are provided (the first was implemented by Porsche), here the switching command is given by the driver, and the control system ensures the quality of such switching. This mode, depending on the manufacturer, may have different names: AUTOSTICK, STEPTRONIC, TIPTRONIC. It is available only on cars with an electronic control system for an automatic transmission, and even then not at all.
What is TipTronic (Video)
The shift knob on vehicles with this system has a special position in which the AUTOSTICK mode is activated. This mode has two non-latching positions, labeled UP ,+, and DN ,-, required to shift into low or high gear. Gear selection in this mode is made by the driver manually, the selector lever is pushed in the direction, -, or, +, - shifting gears up or down. When the engine speed drops to idle, downshifting is automatically carried out only in the canonical design. Some manufacturers of transmissions automatically upshift at the maximum engine speed.
The mechanical part of such a box is indistinguishable from a conventional automatic box, only the control automation and the selector lever have been changed. Such automatic transmissions are characterized by a cutout for moving the selector lever in the form of the letter H, and the symbols, +, and, -,. Still, this mode (AUTOSTICK) is more semi-automatic than manual, since the transmission computer controls the driver's activity and will not allow him to select a gear that exceeds the permissible engine speeds or will not allow him to move from a higher gear. The rest gives the impression of using a manual gearbox. If such a desire arises, then you can easily return to the normal automatic transmission mode by putting the speed mode shift knob in position D, so it’s more likely riding on automatic transmission than "poking" with a pen.
On powerful modifications of cars, sports automatic transmissions are installed, which are equipped with a manual gearshift function. Moreover, such a manual gear shift can be carried out not only by moving the selector up and down, but also with the help of small paddles on the steering wheel, pressing which allows you to lower or increase the steps. This is quite popular on sports cars and executive sedans, which are equipped with powerful engines.
4-speed automatic transmission installed on Audi, VW, Skoda. These boxes are electronic, in many respects their work depends on the electronic units of the automatic transmission, internal combustion engine, ABS, sensors located on the engine and box, and therefore require preliminary computer diagnostics. If, as a result of diagnostics, error codes are not detected, and the automatic transmission does not work correctly, then repair is required. Either the errors indicate that the mechanical problem is a repair.
We remove, disassemble, there are no subtleties in disassembling these automatic transmissions, except for one. In 097 and 01N, there are 2 plugs in the back, one covers the gearbox input shaft nut in the picture - 4198. We need the second one, which we knock out with a hammer and chisel.
Photo 097 and 01N
01P - the same, only the 885 shaft is short, it is knocked out with a hammer and a chisel (a very powerful stopper). The 75 shank is not like that. Instead, the cover is fastened with 3 bolts. Under it, you need to remove the stopper and speedometer gear. After that, you can unscrew and remove the bell.
All these automatic transmissions have a different location of the gearbox, and the mechanical part has 2 types: 096, 097, 098, 099 and 01M, 01N, 01P
The difference is that in 096, 097, 098, 099 gearboxes, the H/T lock is made in the automatic transmission itself, shaft 22 in the picture is inserted into the H/T splines and is rigidly connected to the crankshaft through damper springs. In the 2nd variant, the piston that blocks the g/t is in itself and is controlled by oil pressure through the turbine and reactor shafts.
This part is the same for all types:
26, 43 - Oil pump (there is a difference - 2 types)
839 - Piston 2 and 4 gears
593, 829 - 2nd and 4th clutch package
78 - Clutch housing reverse-input
762 - Clutch piston reverse-input
189, 975 - Reverse-input clutch package
7185 - shims.
White was placed on 096, 097, 098, 099, and green on 01.
61 - Clutch housing forward with a turbine shaft, works in 1, 2 and 3 gears
22 - Clutch housing 3-4 gears. It also performs the function of blocking g / t.
61 - Clutch housing forward, works in 1, 2 and 3 gears
267 - Clutch piston forward
607, 211 - Forward clutch package
22 - Clutch housing 3-4 gears with a turbine shaft.
809 - Clutch piston 3-4 gears.
It's all similar:
792, 445 - Clutch package 3-4 gears
824 - Overrunning clutch separator.
346 - Reverse clutch piston
384, 882 - Reverse clutch package
planetary gear
27 - Planetary gear
74 - Epicycle
Note: the reducer is a separate container. The oil is here.
What changes without fail when repairing this automatic transmission:
Things to watch out for (often fails):
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You can download manuals for these automatic transmissions .
When repairing this automatic transmission, it is imperative to develop an electric pressure regulator, the piston in it must move freely or be replaced with a new one.
To do this, it is necessary to pull out the probe of the machine with the engine running. It usually differs from the engine oil dipstick in the shape of the handle in the form of a red cylinder with a slot in the middle. There are two pairs of marks on the dipstick, the first for a cold engine and the second for a warmed up to operating temperature. Accordingly, the oil mark must be between one or the other pair.
Oil underfill very dangerous thing. Don't allow it. Indirectly, underfilling is indicated by the sound of a vacuum cleaner from the probe hole when the engine is running. When underfilling, the pump pumps oil along with air, which leads to a decrease in line pressure in the lines, a decrease in downforce on the friction clutches and, as a result, slippage of the discs and their accelerated wear. Possible failures when shifting gears.
Oil overflow is no less dangerous. When the oil level is high and the moving parts start to touch the surface, the oil starts to foam. This leads, as in the previous case, to a drop in line pressure in the system. Possible failures when shifting gears. In addition, oil seals may be pressed through and oil leaks may appear.
The slippage of the friction discs leads to their accelerated wear, burning and shedding, which in turn leads to clogging of the oil filter and the suspension of the linear pressure solenoid of the machine and, again, to a drop in linear pressure. A chain reaction begins. On some machines, the filter is made of felt and becomes clogged more actively than the mesh one; it needs to be replaced during repairs.
P-R-N-D-S-L, hold, power These are the operating modes of the machine. They can also include a red button near the selector and a mode lock button on the selector. The red button, when shifted or pressed, allows the machine to be turned on when the ignition is off.
P- PARKING - serves to keep the car in the parking lot. You can switch to this mode only when the car is completely stopped. Accidental inclusion is blocked by the button on the machine selector.
R- REVERSE - reverse. You can switch to this mode only when the car is completely stopped. Accidental inclusion is blocked by the button on the machine selector.
N- NEUTRAL - neutral gear. Not quite the same as on manual boxes. In this gear, you can not roll downhill for a long time or tow the car with the engine off without risking damage to the machine. The oil pump is located on the input shaft of the automatic transmission and therefore does not work in such a situation and the box remains without oil.
D- DRIVE - the most basic mode of operation - driving is allowed in all gears, and there are 4 of them in the machine, first (1), second (2), third (3), fourth or overdrive (4). the fourth gear is similar to the fifth in manual boxes, that is, it is an overdrive, unlike the third, which is a direct gear
When driving, never switch the selector of the machine between positions S-D-N while pressing the button on it. Can accidentally turn on L or R.
S- in this mode, only 1-2-3 gears are included. You can use this mode for engine braking down hills when driving at about 80 km/h.
L- LOAD - in this mode only 1-2 gears are included. Can be used for engine braking from hills when driving at a speed of about 60 km / h. Accidental inclusion is blocked by the button on the machine selector.
HOLD- has a direct impact on modes D-S-L, we denote them as hold on(the light on the panel is on) respectively Dh-Sh-Lh. This mode can be used for manual shifting of 1st and 2nd gears.
Dh- only 2-3 gears are included. The automatic transmission becomes two-speed. The start of movement occurs from the second gear. Switching to third occurs at higher rpm than usual and back to second at lower. You can use this mode for engine braking down hills when driving at about 80 km/h. It is possible when driving around the city to avoid unreasonable switching. But its main use is driving on slippery or loose ground in winter. When starting from second gear, the torque on the drive wheels decreases and, accordingly, the likelihood of slipping of one of them decreases.
Sh- only 2nd gear is engaged. Main application driving in slow motion at speeds of 40...60 km/h
lh- only 1st gear is engaged. The main use is driving in traffic jams at low speeds to brake with the engine and avoid putting your foot on the brake pedal.
To prevent exceeding the maximum engine speed when the button is pressed hold still going upshifting to a higher gear and back.
POWER- The mode of operation of the machine in which all gears are engaged at higher engine speeds. It is not installed on modern machines, when you fully press the gas pedal, the machine still switches at higher speeds.
All of the above applies to Mazda machines. On Toyota cars, the logic of work is different. There, the selector positions limit upshifting to the gear indicated on the selector. That is, at 1, only the first gear is turned on, at 2, only 1 and 2. At 3, 1, 2, 3 are turned on, and if OD is on, then 4. If OD is Off, 4 is not turned on.
Only what is specified by the manufacturer. And Mazda indicates ATF M III (Dexron III according to the classification M o bil, i.e. Mercon III). Not all Dexron oils are the same. Saving on oil in an automatic transmission cannot be compared with the cost of repairing it. Good oils for example M o bil.
Do not fill Dexron II instead of Dexron III. While the oil is cold, the machine will work without comment, but after warming up, it will work inadequately. Then it will crash.
On the engine compartment plate you can find the brand of oil after the letters ATF (Automatic Transmission Fluid). This designation is usually found twice, for power steering and automatic transmission. For power steering, Dexron II is usually used.
Good results are obtained by an additive in the machine called TransX. In some cases, allowing you to extend the period of operation of a faulty automatic transmission before repair for a year.
How to change the oil in the machine?I know three ways to change the oil.
First. The most common. The oil is simply drained through the drain plug of the machine or by removing the pan. And it is poured through the hole for the dipstick. The disadvantage is that in this way almost only half of the volume is drained. So for a complete replacement, you must repeat the procedure several times. In addition, there is a possibility of damaging the gaskets.
Second. It requires special equipment and is used at oil change stations. A thin hose is inserted through the dipstick to control the level, through which the oil is sucked out by the pump. The disadvantage is, as with the first method, not a complete oil change. When lowering, the hose rests on the pan not in its lowest place, in addition, oil remains in the torque converter and radiator. For a complete replacement, you must repeat the procedure several times. The only advantage is that the change does not require a pit and any disassembly.
Third. This method is used by specialists in the repair of machines. Each machine has an oil cooling circuit in the engine radiator. The oil in the torque converter is under high pressure and at high temperature, it would have to boil when it leaves the torque converter. To avoid this, the oil is immediately sent to the radiator for cooling. The replacement procedure is as follows:
The hose is removed (unscrewed) from the machine to the radiator and a similar, but longer one is inserted into its place, the second end of which is lowered into a suitable container. The engine starts and the oil drains under the action of the machine pump. Engine shuts off immediately after draining.
The first can (4 l) of oil for automatic machines is poured through the dipstick (for this we use a funnel with a hose). This is a flushing stage, so you can use the cheapest oil, such as Mitsubishi. The engine is started again and this oil is drained. Only in the last half liters will it be noticeable that the oil is clean! Engine shuts off immediately after draining.
Everything is screwed into place and clean oil from a good manufacturer is poured in, controlling the risks on the dipstick. We start the engine after filling the first 3 liters.
Needless to say, this is the most complete oil change plus torque converter flush. Oil change stations use this method M o bil using special brand equipment Wynn's for oil filling. In addition, as a side effect, pressure in position is measured N automatic transmission. By its size, you can judge the condition of the box.
Go to the service 8-)) Well, of course this is a joke. Who will go to the service if he himself has not tried everything. 8-))
Soon I will describe the diagnosis of the machine by codes. But for now, we're just counting them.
It is necessary to find the diagnostic connector under the engine hood and connect the contacts with a jumper in it TAT(Test Automatic Transmission) and GND(Ground). Switch on the ignition (do not start the engine). Indicator HOLD should light up once for a few seconds and go out. This means that there are no fault codes.
If after that it continues to flash with long or short pulses, we read the codes. A long signal means tens, and a short one means units. For example, one long and 2 short - code 12 - malfunction of the throttle position sensor. Then after a pause comes the next code.
During the operation of the car, there are cases when, when it is started, the voltage in the network drops sharply (with a weak battery, with poor contacts at its terminals, etc.). In this case, false codes appear in the computers of both the automatic transmission and the engine. They must be erased.
Oh, if someone knew this ... There are cases when an automatic machine breaks down, which is operated according to all the canons and has been working for a long time, the maintenance of which was not paid attention at all.
4th gear is disengaged when the oil temperature is below -10 degrees.
There is no lockup (lock-up - torque converter lock) at oil temperatures below +40 degrees and when driving at a speed of less than 120 km / h when the throttle is closed.
From these two points it follows that the precautions for operating the automatic transmission at low temperatures have already been taken and IMHO there is no need to take others (warm up the automatic transmission). Yes, and it seems difficult to me to do this at idle. Firstly, the oil pressure at idle is about 4.5 versus 11 when moving forward and 18 when reversing. Secondly, the oil passes through the engine cooling system, which is still locked to the internal circuit and is in the coldest state, that is, the cooling is more intense.
The selector itself has a lock button that prevents accidental activation R,P or L. To avoid trouble during normal shifting S<->D<->N never press the selector lock button. If you press it every time you shift, you may accidentally engage (for example, during heavy braking at the time of shifting) gears that should be engaged either after a complete stop ( R And P), or at low speed ( L).
To prevent engine over-revving during hold on still going upshifting to a higher gear and back. Small variations on different types of machines.
The automatic transmission has a speed sensor not only for the secondary shaft, but also for the primary. If the speed does not match, the computer turns on the bypass program for this transmission.
There are operating rules on the Internet (60% of them, in my opinion, are rather controversial). Most of the points follow from one another and are apparently written only to use all the letters of the alphabet from A to Z. I have singled out only the really harmful ones.
Destroy automatic transmission:
Low and high oil level
towing a car with automatic transmission over long distances and at high speed, the 50x50 principle is considered the normal mode, that is, no more than 50 km and no more than 50 km / h
driving on low-quality or old oil or not corresponding to the manual (Dexron-II instead of Dexron-III, for example)
driving with an overheated engine and, therefore, on an overheated gearbox
I'll add my own points:
operating a car with a discharged or in poor condition battery if the box is electronically controlled.
towing by a passenger car with an automatic transmission of a truck.
overcoming deep water barriers when the automatic transmission breather enters the water. In this case, due to the sudden cooling of the body, water enters through the breather. Due to moisture, the friction clutches and the torque converter lockup clutch are separated.
There are many different verification methods, but we will focus on the five main ones.
1. Oil level and condition. The level must correspond to the risks at a given temperature. The oil should not smell like a sharp burn, it should be pure red (maybe a slight darkening) and when rubbed on the finger from the dipstick, there should be no noticeable impurities. If the oil is drained into a container, then when it is stirred, it should not leave whitish streaks.
2. Ready time. We warm up the engine to normal idle speed. Standing on the brake switch N-->D And N-->Dh and note the time until the push, indicating that the machine has turned on, this time should be 0.5s ... 1s. Similarly, we switch N-->R and also note the time, it should be less than 1.2 s. Time greater than the specified indicates wear of the friction clutches. Similarly N-->Dh. On Toyota cars, these times are longer by 0.2 ... 0.3 s.
3. parking test. Make sure that the engine idle speed and ignition timing are correct. Turn off all energy consumers (air conditioner, radio, ventilation and heating of seats and rear window, headlights). At the same time, we press the foot brake, switch the selector to D and press the gas pedal to the floor. We notice the maximum engine speed on the tachometer. You can not keep this mode for more than 5 seconds.
Switch to S, R And L and repeat. Compare with the table. Breaks between tests should be at least a minute!
| Model | Min | Max |
| RX7 | 3000 | 3300 |
| 929 | 1950 | 2250 |
| B2200 | ||
| carburetor | 1800 | 2200 |
| EGI-FI | 1850 | 2250 |
| B2600 | 2100 | 2500 |
| Miata (MX-5) | ||
| 1993 | 2600 | 3000 |
| 1994 | 1900 | 2100 |
| MPV | 1800 | 2200 |
4. Road test. To conduct this test, a preferably flat and straight section of the road is not controlled by traffic police radars.
Check the position of the selector and its indication on the instrument panel.
Switch the selector to D. Accelerate and then slow down the car at full and half throttle. Make sure you are switching 1-->2 , 2-->3 , 3-->4 And 4-->3 , 3-->2 , 2-->1 .
When moving to 4 th gear, switch the selector to the position S and make sure the switch happens immediately 4-->3 .
Turn on the mode Dh. Check that the switch is in progress 2-->3 And 3-->2 and no inclusion 1 And 4 .
Slow down the car. Make sure engine braking is on 3 And 2 gears at 1/8 throttle opening or less.
When moving to 2, 3 And 4 gears, make sure that you do not hear unusual noise (grinding) or vibration when lightly pressing the gas pedal in the range of 40 ... 60 km / h.
5. Diagnostics by codes. It is necessary to find the diagnostic connector under the engine hood and connect the contacts with a jumper in it TAT And GND. Switch on the ignition (do not start the engine). Bulb HOLD should light up once for a few seconds and go out. If after that it continues to flash with long or short pulses, the automatic transmission needs to be repaired. During the operation of the car, there are cases when, when starting, its voltage in the network drops sharply (with a weak battery, with poor contacts at its terminals, etc.). In this case, false codes appear in the computers of both the automatic transmission and the engine. This is how you have to deal with them.
Here is a summary of the automatic transmission diagnostics. Diagnostic codes are described in more detail. The best results in diagnosing the mechanical part of the automatic transmission are obtained by connecting a pressure gauge to the box and checking the line pressure in all modes. But this requires special equipment and must be carried out in specialized workshops.
I deliberately do not interpret the results obtained here, since this is already the business of auto repair specialists. I will only note that if it does not meet the normal parameters, it is better not to buy a car with such an automatic machine, since it needs repair. However, if you really want to, then you can. But then you need to get a discount on its repair. In Vladivostok, repairing an automatic machine costs between $200 and $500. In some services up to $ 1000, which, however, does not affect the quality of the repair. A used machine costs from $150. Installing it on a car - 1000 rubles. ATF will cost about 100 ... 150 rubles per liter.
At the same time, it is also impossible to say that with a machine gun that has passed all the tests you will drive for at least a year.
To protect the automatic transmission, Japanese engineers have provided a number of restrictions in the operating mode:
4th gear (OD) is disengaged when the oil temperature is below -10 degrees.
no lockup at oil temperatures below +40 degrees.
From these two points it follows that the precautions for operating the automatic transmission at low temperatures have already been taken and IMHO there is no need to warm up the automatic transmission. Yes, and it is almost impossible to do this at idle. Firstly, the oil pressure at idle is about 4.5 versus 11 when moving forward and 18 when reversing. Secondly, the oil passes through the engine cooling system, which is still locked to the internal circuit and is in the coldest state, that is, the cooling is more intense.
This does not mean that you can drive sharply on a cold box. Since the oil is still cold and more viscous, switching occurs with greater delays and consequently with disc or belt slippage. Which is not good, but not fatal either. The number of switching operations on a cold box should be limited. For example, moving in the mode hold, or even 1h->2h->3h until you leave the garage or parking lot and the engine is still warm.
The criterion for warming up the box to normal mode can be the time the gear is switched on. If it is normal, then the machine is warm enough. Let me remind you that on Mazda it is 0.5 ... 1 s, and on Toyota 0.8 ... 1.3 s.
The very formulation of the question in relation to automatic transmission is incorrect.
The main element of an automatic transmission is not a set of shafts with pairs of gears that engage during mechanical movement of the gear selector, as is done on mechanical transmissions. The basis of an automatic transmission is a planetary gearbox. And just one of the properties of planetary gearboxes is that when the clutch or brake band is activated, smooth
change in the gear ratio of the box during the time of full operation (0.5 ... 1 s). And, accordingly, the transmission of torque from the engine to the wheels does not stop even for a fraction of a second.
All of the above applies to engine braking on a car with automatic transmission. That is, the braking force changes smoothly, without interruption for a fraction of a second, with the appropriate actions of the driver.
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 we are used to seeing it, 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.
