Will an Automatic Transmission Car Move Forward by Itself When Shifted to D Gear?
1 Answers
Most automatic transmission cars will move forward by themselves when shifted to D gear and the brake is released. Those that do not move are generally supercars or some small-displacement dual-clutch transmission vehicles, which is related to the type of power coupling device in the transmission. During driving, if you need to stop and wait, it is best to shift the car's gear to P gear. The D gear is located behind the N gear in the middle and rear of the gearshift console, designed to allow the car to automatically select gears while moving forward. When an automatic transmission car is shifted to D gear, the engine and transmission are not rigidly connected but are linked through a torque converter. The working principle is that the engine's power is transmitted sequentially through the torque converter's internal pump wheel, guide wheel, and turbine to the transmission input shaft. The three wheels of the torque converter are independent of each other, with automatic transmission fluid acting as the medium. When the engine drives the pump wheel to rotate, the agitated fluid will cause the turbine to rotate as well, enabling power transmission and allowing the vehicle to move forward automatically. Therefore, automatic transmission cars generally move forward by themselves when shifted to D gear. The transmission structure of supercars is different from that of ordinary household models. Supercars use competition-style clutch plates in their transmissions to prevent slippage. These clutch plates are similar to those in manual transmission cars, operating in a semi-engaged state. Due to the high torque of supercars, shifting to the forward gear (i.e., the semi-clutch state) will not cause the vehicle to move forward to protect the clutch from excessive wear. Therefore, supercars will not move forward when shifted to the forward gear without applying throttle.
