What is the reason why an automatic transmission car does not move when shifted to R gear without pressing the accelerator?
4 Answers
There may be several reasons why an automatic transmission car does not move when the accelerator is pressed: The clutch is not fully engaged; the handbrake is not released; the gear is stuck and not fully engaged; the clutch friction plate is worn out. The correct driving method for an automatic transmission car: Start the engine with the gear lever in P position, and you must press the brake pedal before shifting from P to other gears. When starting, push the gear lever to a lower gear (i.e., 2 or 1, some may have 3), and after the speed increases to a certain level, shift to D gear for normal driving. If cruising at high speed on the highway, you can use the O/D gear to save fuel. When starting, the following points must be noted: Shift gears only after pressing the brake pedal, and check if the gear lever position is correct; when starting over bumps or steps, it is best to press the brake pedal with the right foot, slightly release the right foot while the car is stationary, and slightly press the accelerator pedal at the same time. Lift the right foot immediately after crossing the step and lightly press the brake pedal to prevent severe shaking of the vehicle; do not let the engine speed be too high when starting. Especially in winter, when the air conditioning rapid acceleration device is working, the idle speed may exceed 1500r/min (usually 1000r/min), which can cause strong vibration and gear impact, leading to a sudden start. Therefore, wait for the engine speed to drop before starting.
I used to drive an automatic transmission car and encountered situations where the car wouldn't move when shifted into R gear without pressing the accelerator. This was mostly due to the engine idle speed being too low, especially on slight slopes. When reversing an automatic car, the engine's natural RPM can't handle the transmission load, particularly when the car is heavy or there are small obstacles on the ground. In such cases, pressing the accelerator slightly can solve the problem. However, if this happens frequently, it might indicate old transmission fluid or an issue with the engine idle speed setting, requiring inspection and repair. Another possibility is the hill start assist function being activated; while it enhances safety, it can sometimes misjudge and cause insufficient power—try turning it off. Overall, regular transmission maintenance can prevent these minor issues.
When an automatic transmission vehicle doesn't move in R gear without pressing the accelerator, from a mechanical perspective, it's usually due to insufficient engine idle torque output. In transmission design, the torque at idle is relatively low, and if the vehicle is on a slight slope or encounters resistance, power transmission may be interrupted. Another factor could be incomplete engagement of the torque converter, especially during cold starts. I recommend first checking if the ground is level and avoiding operation on slopes. Meanwhile, observe the engine tachometer – if the idle speed is normal but the vehicle doesn't move, it may indicate more serious issues like deteriorated transmission fluid or sensor failure, requiring prompt professional inspection. Developing the habit of gently pressing the accelerator when reversing is safer for daily operation.
When I first started learning to drive, I was also confused about this. If an automatic transmission car doesn't move when shifted into reverse, it's mostly a normal safety feature to prevent sudden accidental reversing. The engine's idle power isn't enough to move the car, especially on small slopes or with heavy vehicles—just press the accelerator to start moving. Don't worry about major issues; my first few times I thought the car was broken, but it turned out I just hadn't adjusted my driving posture properly. With more practice, you'll get used to it. Always check for level ground before reversing for extra safety.
