Automatic transmissions differ significantly from manual transmissions:
Manual transmissions achieve gear changes by adjusting different gear combinations, whereas automatic transmissions achieve speed variation through hydraulic power transfer and gear combinations. The torque converter is the most distinctive component of an automatic transmission, comprising elements such as the pump impeller, turbine, and stator. The pump impeller and turbine form a working pair, where the pump impeller drives the turbine to rotate via fluid, and the stator between the pump impeller and turbine creates a speed difference and achieves torque and speed conversion through reactive force. For the driver, simply pressing the pedal with varying force allows the transmission to automatically shift gears up or down.
To improve efficiency, several rows of planetary gears are connected in series behind the turbine. The hydraulic control system automatically operates these planetary gears in response to engine operation, thereby achieving automatic speed and torque conversion. To meet various demands during driving, such as parking and reversing, automatic transmissions also feature several manual lever positions, such as P (Park), R (Reverse), N (Neutral), and D (Drive).
In terms of performance, the more gears an automatic transmission has, the smoother the vehicle's operation, the better its acceleration, and the more fuel-efficient it becomes. Automatic transmissions offer a relaxed and comfortable driving experience, but their power response is not as direct, which slightly diminishes "driving pleasure." Additionally, due to the use of hydraulic transmission, there is some power loss in automatic transmissions.
