Automatic transmission, also known as torque converter transmission, is the name of the system that automatically changes gears in accordance with the load and road condition of the car, apart from the one in vehicles with manual transmission. It is not used in cars with automatic transmission as the clutch pedal is not needed. Gear shifts in automatic transmission vehicles are made by the automatic transmission brain. It provides hydraulic gear shifts with the control of solenoids in line with the commands coming from the ECU.
The interior of an automatic transmission generally consists of three parts:
1- Torque converter,
2- Shift gears,
3- Hydraulic control.
What are Automatic Transmission Drive Modes? What are the Differences?
Fully automatic transmission; There are three different driving options: Sport mode, Auto mode and Manual mode.
I – What is Auto Mode?
Auto mode is designed for normal quiet use. It prevents the engine speed from getting too high by changing the gear shifts earlier. The low-speed operation of the engine not only saves fuel; but also reduces the sound level to a minimum. While the number of gears is reduced in proportion to the speed of conventional fully automatic vehicles, the fully automatic transmission also continuously increases the number of gears when accelerating and entering a stable state.
II – What is Sport Mode?
In Sport mode; the car’s accelerator pedal reactions become more sensitive, keeping the engine’s power band short. Gear shifts take place at higher revs, allowing more use of the engine’s power. In this way, both the engine noise will increase and the response time will be shortened due to its operation at high revs. In addition, when the car is in sport mode; the transmission behaves more aggressively during the downshifting phase, resulting in less accelerator pedal pressure.
III – What is Manual Mode?
As with other automatic transmission types, it provides manual operation. The driver can perform gear shifts from the paddle shifts behind the steering wheel or the “+/-” positions on the gear lever. Due to the gearbox protection, even if you have control, the ECU intervenes in late gear changes and makes the gear shifts automatically. In other words, if the gear shifts are forgotten while in manual mode, the vehicle will change the gear itself.
What is Torque Converter? How it Works?
In order to change gear in a manual gearbox; you must first depress the clutch pedal and thus neutralize the engine. At the end of this process, you change gear. However, automatic transmission cars do not have a clutch system. They use a torque converter. If you are in “D” gear, your vehicle will still continue to move slowly; even if your foot does not step on the gas. Because the Torque converter always transmits some of its power uninterruptedly. A system to cut this is not used yet.
Planetary gear mechanism consists of orbital gear, sun gear and planetary gears engaged on both gears and also bearing on the planet carrier. The hydraulic control consists of a pump that is rotated by the engine, the valves that direct the fluids pushed by this pump, and hydraulic clutches that are pushed and pulled by them, enabling the required gears to engage at the required engine speeds. Thanks to the torque converter, which replaces the traditional clutch, there is no full connection between the engine and the wheels at low speeds, so it is well suited to traffic situations such as uphill starting without slipping back, or a very slow-moving queue of cars, but it also causes delays in behavior and wastes fuel. At very high speeds, either the torque converter provides a tight enough grip, or a real auto-engage clutch is engaged.
How to Identify a Fully Automatic Transmission Failure?
There is a popular belief that automatic transmission is weak and breaks down more quickly. When we look at the old models, although there is some justification; this belief has started to disappear gradually with the development of technology and the automotive industry’s experience in transmission. Today, automatic transmissions are more durable and longer lasting than manual transmissions. Because user error has less effect on automatic transmissions. You should know that if you use the automatic transmission by learning small details; you will not encounter any problems. The important point is that; the driving error should not be made in the use of automatic transmission.
In Which Vehicles Is Fully Automatic Transmission Used?
Some models using a new generation torque converter fully automatic transmission;
New Generation BMW M5 (8 speed transmission)
Jaguar F-type (8-speed transmission)
Aston Martin (8 speed transmission)
Mercedes 7G Tronic, Tronic Plus
Citroen, Peugeot EAT6
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Reference: This page was created by Btperformance.