Why does an automatic transmission car never stall no matter how you drive it? And is it easy for a manual transmission car to stall?

Although I obtained a C1 driver's license, many people actually don't want to buy a manual transmission when buying a car because they are afraid of driving it poorly and dare not drive it normally. One important reason is that manual transmission is particularly prone to stalling, and if the clutch and throttle do not work properly, the engine will stall when starting. For automatic transmission cars, even novice drivers will not stall no matter how they drive. As long as they control the direction and speed well, novice drivers can quickly get started without the need for any fuel separation cooperation. So why is it easy for a manual transmission to stall, while an automatic transmission won't?

This is due to the different working principles of the gearbox. After the manual transmission is put into gear and the clutch is released, the connection between the engine and transmission is hard. The flywheel of the engine transmits power to the clutch plate, which drives the input shaft to rotate, then drives various gears, and finally drives the output shaft. It is all mechanically hard connected, and power transmission is almost without loss. Unlike automatic transmission cars, their power transmission relies on transmission oil, which creates pressure to drive the rotation of various components of the transmission. This is a soft connection and results in greater power loss.

Due to the hard connection of manual transmission, the engine can drive the wheels to rotate, and in turn, the wheels can also constrain the engine's rotation. Assuming the accelerator is lightly pressed, the engine output force is very small, and at this time, the force required for the wheels to rotate is very large, and the engine will not be able to rotate. Due to the fact that only the ignition stroke of the engine does external work, the other three strokes rely on inertia for operation. Once the engine stops running, it will lose one stroke and will definitely shut down immediately. It can be understood as the engine rotating there, and if you use a lot of force to hold it from turning, it can only stall.

Let's take a look at automatic transmission cars. As there is transmission oil between the engine and gearbox, it is a soft connection. Even if the wheels are stuck and cannot rotate, the constraint on the engine is not significant, and the engine can still operate normally. For example, it is relatively easy to understand that their power transmission is like two electric fans blowing opposite each other, one powered on and the other not powered on. The powered rotary hair dryer will drive the non powered one to rotate as well. A powered fan is equivalent to an engine, while a non powered fan is equivalent to a gearbox. In the case of low resistance, the rotation speed of the two fans should be almost the same. If a non powered fan is subjected to significant resistance, it is simply that it cannot rotate and does not affect the rotation of the powered fan. On the car, even if the wheel resistance is high, it does not affect the engine and will not cause the engine to stall.

Although manual transmission is prone to stalling, it has an advantage that in the event of battery depletion, the car can be pushed to start without the need to connect the battery. For automatic transmission, the battery must be connected and cannot be pushed to start. Or because the manual transmission is hard connected, the wheels can drive the engine to rotate. When pushing the car, the wheels rotate, which drives the engine to rotate. The effect is the same as that of the starter motor driving rotation, which can land the car. The automatic transmission is a soft connection, and the rotation of the wheels does not drive the engine to rotate. The pushing effect is the same in N gear and D gear, and the engine does not rotate, so it cannot ignite. 

                                                                                                                                                                                                                          From：WONDEE Autoparts

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