Classic automatic transmission
Classic automatic transmissions have several gear stages, usually from 4 to 6. Their operation is based on the hydromechanical principle, where engine torque is transmitted through a torque converter and planetary gears.
Torque converter
A torque converter is a device that transmits torque from the engine to the gearbox. It consists of three main components:
* Turbine: Connected to the engine.
* Pump: Connected to gearbox.
* Stator: Located between the turbine and the pump.
When the engine is running, the pump creates a stream of pressurized fluid that rotates the turbine. The stator directs the flow of fluid, increasing the torque transmitted to the gearbox.
Planetary gears
Planetary gears are mechanisms that provide different gear ratios in a gearbox. They consist of the following components:
* Sun Gear: The center gear associated with the input shaft.
* Planetary Gears: Small gears that rotate around the sun gear.
*Ring Gear: The outer gear associated with the output shaft.
Different combinations of meshing between these gears create different gear ratios.
Control
Automatic transmissions are controlled by an electronic control unit (ECU), which receives input signals from engine and transmission sensors. The ECU selects the appropriate gear based on driving conditions such as speed, engine load and accelerator pedal position.
Advantages
* Smooth gear shifting
*Easy to use
* Possibility of selecting different driving modes (e.g. economical, sporty)
Flaws
* Lower fuel efficiency compared to manual transmission
*Higher maintenance cost
* More complex design