What do D3, D2, D1 mean in automatic transmission?
1 Answers
D1, D2, and D3 in automatic transmission refer to the low-gear modes of the gearbox. D1 manually locks the car's gear in first gear, overriding the vehicle's automatic control. D2 locks the gear in second gear, not exceeding second gear, allowing the car to shift automatically between first and second gears. D3 locks the gear in third gear, allowing automatic shifting between first, second, and third gears, but not exceeding third gear. Scenarios where D1, D2, and D3 can be used are as follows: 1. D1 and D2 can be used when going uphill, especially on steep slopes. Manually setting the gear to first or second gear is similar to using a manual transmission on a steep incline. The low gear provides higher torque, making it easier to climb. While this isn't the primary purpose (since D mode can also handle it), locking the gear prevents frequent shifting in D mode. 2. The advantage of D3 is faster response when overtaking. At speeds of 80 km/h, the gear is usually in 5th or 6th. If you need to overtake quickly, the automatic transmission will gradually downshift from 6th to 5th, 4th, and then 3rd, which takes time. By directly shifting to D3, the gear immediately changes to 3rd, providing the fastest response for instant acceleration. After overtaking, you can shift back to D mode. 3. The biggest benefit of D1 and D2 is when driving downhill. In D mode, even without pressing the accelerator, the car will accelerate, making it difficult to control and potentially dangerous. However, when shifted to D2, the car descends slowly due to the resistance from the transmission and engine, improving safety and control. Some cars even promote a "hill descent control" feature, which achieves the same effect with a simple button press.
