Driving skills often hear a word called "engine braking". What does it mean and what is the difference between foot braking and hand braking. In short, engine braking is the process of decelerating the vehicle by using the resistance of engine operation. When the actual driving speed of the car is greater than the driving speed under this gear and accelerator, it enters the engine braking state.

For example, when the vehicle is running at the speed of 60km / h, if you only release the accelerator without cutting off the gear and are in the sliding state with gear, the forward movement of the vehicle in the future will be braked by the engine. At this time, instead of the engine driving the wheels through the gearbox, the wheels drive the engine through the gearbox. Although there is no filler door, the engine still maintains a high speed.

Because the wheel speed is fast and the connection between the wheel and the engine is not disconnected, it is bound to drive the engine to reach the corresponding speed. For example, now in gear 5, it takes 1500 revolutions to accelerate to 60km / h, so the wheel will drive the engine to 1500 revolutions. If it takes 2000 revolutions to accelerate to 60km / h in gear 4, the wheel will drive the engine to 2000 revolutions.

If the accelerator is released at the speed of 60km / h, the gear is cut off and the engine is in neutral sliding state, there will be no engine braking. Because there is no connection between the engine and the wheel, at this time, the engine is at idle speed, and the wheel speed will be affected by the road conditions at that time. The downhill will be faster and faster, and the uphill or flat road will gradually slow down.

In other words, the car does not cut off the gear, the engine and wheels are always connected, and their corresponding speed and speed correspond one by one. If the engine rotates fast, it will rotate fast with motor car wheels; The wheel turns fast, which in turn drives the engine to turn fast. Because the engine rotation has to overcome a lot of resistance, such as compression resistance, exhaust resistance, friction resistance, resistance to drive various accessories, etc. Therefore, when the wheel drives the engine to rotate, these resistances are overcome by the force transmitted by the wheel, so as to achieve the purpose of reducing the wheel speed.

When driving on long downhill sections, you should choose to brake with the engine, which can reduce the time of stepping on the brake and prevent the brake from overheating, attenuation and even failure. Because of different transmission ratios, the lower the gear, the better the engine braking effect. Therefore, it is necessary to decide how many gears to engage for sliding according to the slope and the desired driving speed.