Automatic transmission (AT)
* Operating principle: Uses planetary gearbox and electronic control unit (ECU) to automatically change gears depending on vehicle speed and engine load.
* Types: Hydromechanical (uses a torque converter to transmit torque), robotic (uses a mechanical clutch controlled by an ECU), continuously variable transmission (CVT).
*Advantages: Ease of driving, smooth gear shifting, reduced load on the driver.
* Disadvantages: Higher fuel consumption and more expensive to maintain compared to manual transmissions.
Variable speed transmission (CVT)
* Operating principle: Uses two variable diameter pulleys connected by a belt or chain. The pulleys expand and contract, continuously changing the gear ratio.
* Types: V-belt CVT, chain CVT.
*Advantages: Smooth and linear acceleration, low fuel consumption, light weight and size.
* Disadvantages: Limited torque transmission capabilities, possible belt or chain slippage under high loads.
Comparison:
| Characteristics | Automatic | CVT |
|—|—|—|
| Working principle | Planetary Gearbox | CVT |
| Number of gears | Fixed | Continuously changing |
| Ease of driving | High | High |
| Fuel economy | Average | High |
| Maintenance cost | More expensive | Less expensive |
| Torque transmission | Good | Limited |
| Weight and size | Heavier | Lighter and more compact |