Drivers know that when a car goes downhill, braking for a long time may cause the brake to fail.

    Why does this happen? In the final analysis, it is a "hot" word. From the high to the low, the car changes from the potential energy to the kinetic energy, and then changes the kinetic energy into the friction heat of the brake, and most of the heat will be produced in the brake, making the brake temperature up to 300 degrees centigrade.

    Under normal circumstances, the working temperature of the brake can not exceed 200 degrees. When the temperature is too high, the brake skin (film) surface is easy to burn. After hardening, the friction coefficient of brake pad will obviously decrease, and the braking efficiency will decline. This is possible for vehicles that use hydraulic and pneumatic braking.

    Nowadays, the small and medium cars are usually equipped with hydraulic power brakes, and the downhill often uses brakes. The heat produced will also be carried through the pipeline, which makes the temperature of the hydraulic oil rise. When the temperature exceeds the boiling point of the hydraulic oil, the oil will vaporize, so that the brake pressure will also be insufficient