In order to ensure the safety of the brake pipe, the service brake system of all modern cars adopts dual-line brakes. The dual-line hydraulic brake transmission device uses independent dual-chamber master cylinders to control the wheel brakes of the two or three axles through two sets of independent pipelines. Its characteristic is that if one of the pipelines fails, the other pipeline can still continue to brake, thereby improving the reliability of automobile braking and driving safety.

The main pipeline distribution forms are:
①One shaft to one shaft type: The front wheel brake and the rear wheel brake each have a set of pipelines. This arrangement is the simplest. It is generally used in an arrangement of front-end rear-wheel drive of the engine. The disadvantage is that a certain pipeline fails. At this time, the ratio of the front and rear axle braking force distribution is destroyed.
②Cross type (X type): The two wheels in the diagonal direction of the front and rear wheels share a set of pipelines. When any pipeline fails, the remaining total braking force can be maintained at 50% of the normal value, and the front and rear axles are controlled. The power distribution ratio remains unchanged, which helps to improve braking stability. This form is mostly used in front-drive cars.
③One-shaft half-to-half axle type: each front wheel brake is required to have two wheel cylinders, one wheel cylinder of each front wheel brake and all rear wheel brake wheel cylinders belong to a set of pipelines, and the remaining front wheel cylinders belong to Another casing circuit.
④Semi-shaft, one-wheel-to-half-shaft, one-wheel type (LL type): each front wheel brake is required to have two wheel cylinders, and the two sleeve circuits are for each front wheel brake and one rear wheel brake wheel cylinder. kick in. When any casing circuit fails, the front and rear wheel braking force ratio is the same as the normal situation, and the remaining total braking force can reach 80% of the normal value.
⑤Double semi-axle to double semi-axle type (HH type): It is required that each brake has two wheel cylinders, and each set of brake pipelines controls one wheel cylinder of each brake. When any casing circuit fails, the braking ratio of the front and rear wheels is the same as the normal value, and the remaining total braking force can reach 50% of the normal value.
So when a pipeline is broken, it does not mean that the entire brake system is useless, but the braking force becomes worse, and it can be used at low speeds, but for your safety, it is better to repair it at speed.