Automatic transmission (AT)
An automatic transmission (AT) is a type of transmission that automatically selects the correct gear ratio for the vehicle based on its speed and load. It frees the driver from having to manually change gears and allows him to concentrate on driving.
How does automatic transmission work:
The automatic transmission uses a hydraulic system, which is controlled by an electronic control unit. The system uses:
*Hydraulic Torque Converter: It transfers power from the engine to the transmission and acts as a clutch, allowing you to shift gears smoothly without loss of power.
* Planetary gears: They are the basic elements that provide various gear ratios.
* Bands and Clutches: These are used to engage and disengage planetary gears and ensure smooth gear shifting.
* Oil Pump: It provides the fluid pressure required to operate the hydraulic system.
* Electronic control unit: It interprets the sensor signals and determines when and which gear to engage.
Advantages of automatic transmission:
* Easy controllability: Automatic transmission frees the driver from the need to manually change gears, which makes driving easier and more comfortable.
* Smooth Ride: Gear shifts smoothly without jerking or vibration, providing a more enjoyable driving experience.
* Fuel Economy: Some automatic transmissions have higher gear ratios that help save fuel at high speeds.
* Engine Protection: The automatic transmission prevents engine oversteering by automatically downshifting under hard acceleration or heavy load.
Disadvantages of automatic transmission:
*Higher cost: Automatic transmissions are usually more expensive than manual transmissions.
* More complex design: Automatic transmissions require more maintenance and repair than manual transmissions.
*Power Loss: The hydraulic torque converter may reduce power slightly compared to a manual transmission.
*Limited Performance: Automatic transmissions are generally not designed for high-performance vehicles due to their torque and shift time limitations.
Automatic transmission types:
There are several types of automatic transmissions, including:
* Classic automatic transmissions: Use a hydraulic torque converter and planetary gears.
*Dual Clutch Transmissions (DCT): Combines elements of both automatic transmission and manual transmission, providing faster and smoother gear changes.
* Variable Variable Transmissions (CVT): Use a belt or chain mechanism to provide continuously variable transmission ratios.