After driving for a period of time, a novice will find out why the car can’t step on the brake when the car is turned off. What is the reason? Let’s take a look at why the car can’t step on the brake when the car is turned off.
It is normal to be unable to step on the brakes after the engine is turned off. Basically, all cars are designed in this way, because the brake system is not directly driven by the feet. There is a brake booster pump in the middle to assist, and only the engine works. The booster pump will be driven.
The reason why the car can’t be braked when the car is turned off is here:
The booster relies on the vacuum generated when the engine is running To generate the boost, the engine is turned off and the vacuum is gone. The less the vacuum stored by the booster is used, the harder it is to step on.
After turning off the engine, the brake assist does not work. For a naturally aspirated engine, the boosted vacuum comes from the throttling effect of the intake pipe throttle, and for a turbocharged engine, the vacuum comes from the vacuum pump. Therefore, the vacuum can only be generated when the engine is running. After the engine is turned off, the vacuum source is no longer continuous, and there is no way to provide assistance.