What is the working principle of an automatic transmission (AT)?

[LeEmilio]

Automatic transmission (AT) working principle: In a space filled with hydraulic oil, two turbine blades are installed, connected to the power input end and output end respectively. The powerful vortex generated by the impeller at the power input end drives the impeller at the output end, thereby achieving power transmission. The core of the automatic transmission lies in achieving automatic gear shifting, which uses clutch shifting to enable uninterrupted power shifting, ensuring smooth gear changes. Automatic shifting means that while the car is in motion, the driver presses the accelerator pedal as needed during the driving process, and the automatic transmission can automatically shift into different gears based on the engine load and the vehicle's operating conditions.

[SkylarFitz]

I've always been a car enthusiast, and the working principle of automatic transmissions is quite fascinating. Unlike manual transmissions that require clutch pedals and gear shifting, it transfers power through a component called a torque converter, where hydraulic fluid flow drives turbine blades, connecting the engine to the gear set. The core lies in the planetary gear system, composed of a sun gear, planet gears, and a ring gear, which can alter gear ratios—for example, higher ratios at low speeds and lower ones at high speeds, helping the car accelerate smoothly. The computer control unit constantly monitors vehicle speed, throttle position, and engine load to automatically determine shift points. When the data reaches preset values, the hydraulic system engages clutches and brake bands to switch gears, all happening seamlessly without the jerky feeling of manual operation. What I love most is its convenience in traffic jams, eliminating constant gear changes and reducing fatigue. But remember to change the transmission fluid regularly to keep the system clean, which extends its lifespan and prevents sluggish shifting. Overall, this automatic adjustment makes driving easier and safer.

[McJeremiah]

Having driven for decades, I can confidently say that automatic transmissions are a game-changer in modern driving. They operate by using a torque converter filled with fluid to transmit engine torque, preventing power loss. Planetary gear sets work behind the scenes to handle different speed requirements, while the computer system reads sensor data to determine when to upshift or downshift, with hydraulic mechanisms executing the shifts. This eliminates the need for manual operation, especially during high-speed driving or in heavy traffic, ensuring smooth gear transitions and preventing sudden stalling. From personal experience, when the transmission responds quickly and shifts smoothly, the driving experience improves significantly, allowing for better focus on the road. It's worth noting that transmission fluid temperature and aging can impact performance, so it's advisable to have it checked every few tens of thousands of kilometers. Understanding this, I pay closer attention to warning lights during daily driving, such as signs of jerky shifting, to address potential safety hazards promptly. This technology not only enhances convenience but also boosts reliability in various driving scenarios.

[VanElijah]

I'm particularly curious about how automatic transmissions work. Simply put, they use a torque converter instead of a clutch, transmitting power through hydraulic fluid flow. Planetary gear sets change gear ratios to adapt to different speeds. The computer module monitors vehicle speed and engine conditions, automatically selecting gears, then the hydraulic system controls component switching for smooth gear changes. The entire process operates in the background, making driving easier without jerky shifts. I've also noticed this design is more fuel-efficient than manual transmissions, especially in stop-and-go traffic, as it optimizes shift timing. Understanding this, I realize transmission maintenance is crucial - like regularly changing the fluid filter to prevent sticking. This knowledge helps me use my car better.