When the brakes become soft, the braking force is abnormally weakened. There are usually three kinds of faults. Because: the first type is that the oil pressure of the sub-pump or the main pump is not enough, and oil leakage may occur; The second type is the brake fault, such as the brake pad and the brake disc are stuck; The three types are that the brake pipe leaks into the air. If the brakes are continuous for several legs, the pedal height is slightly. It has a high and elastic feel, indicating that air is infiltrated into the brake pipe.