How Does an Automatic Transmission Work?
3 Answers
Automatic transmission works by utilizing planetary gear sets to change gears. It automatically shifts gears based on the degree of throttle pedal input and vehicle speed changes, allowing the driver to simply control the speed by operating the accelerator pedal. The functions of automatic transmission are: 1. Enabling the vehicle to move in reverse while maintaining the engine's rotation direction; 2. Using neutral gear to interrupt power transmission, allowing the engine to start, idle, and facilitating gear shifting or power output; 3. Changing the gear ratio to expand the range of torque and speed variations at the drive wheels, adapting to constantly changing driving conditions while keeping the engine operating under favorable conditions.
Actually, an automatic transmission is like a smart assistant that makes driving much easier. At its core, it uses a torque converter to replace the traditional clutch - when the engine rotates, the fluid inside the torque converter transmits the power. The transmission also contains planetary gear sets, an ingenious design that achieves different gears through various gear combinations. The most impressive part is the control computer, which constantly monitors data like vehicle speed and throttle position to command the hydraulic system for automatic gear changes. For example, when you press the accelerator to speed up, the transmission senses the RPM change and proactively downshifts. When stopping at a red light, the torque converter can cushion the power to prevent stalling. Modern luxury car transmissions now have seven or eight gears, with computer algorithms enabling fast and smooth shifts that are barely noticeable.
I've been driving automatic transmission cars for over a decade, and I feel their biggest advantage is the peace of mind they offer. You don't have to think about shifting gears while driving; just press the accelerator or brake as needed. This is especially noticeable in traffic jams—while manual transmissions require constant clutch engagement and gear shifting, automatics handle it all smoothly on their own. I remember once driving on a mountain road where the transmission downshifted automatically and very timely, providing ample power for climbing. At its core, it's controlled by a computer, with sensors inside the transmission constantly monitoring the car's condition and automatically selecting the optimal gear based on how hard you press the accelerator. When the hydraulic system executes the gear shift, the arrangement of planetary gear sets makes it much smoother than a manual transmission. Nowadays, many cars also come with sport mode or snow mode, which essentially alter the computer's shifting logic, making them particularly practical.
