First of all, we need to know that the braking system of a truck is usually divided into oil brakes and air brakes. Oil brakes have a slightly slower reaction speed and low strength. Generally, oil brakes are mostly used in microvans, micro trucks and other models. They are characterized by small size, light weight and simple structure.
Air brakes have a quick reaction speed and strong braking force. They are mostly used in medium and heavy trucks. They have large parts such as air tanks and brake cylinders. Now many light trucks have also changed from oil brakes to air brakes. The four-circuit protection valve exists in the air brake system and is used to divert and protect the air pressure pipeline of the whole vehicle.
The four-circuit protection valve is essentially a five-way valve. Its internal structure is a diaphragm type, mainly composed of a housing, a diaphragm, a valve, a transmission ring, a push plate, a pressure regulating spring, etc. There is an air inlet and four air outlets. The air outlets correspond to the front axle braking system and the middle and rear axle braking systems, respectively, connecting the parking brake system and the auxiliary brake system.
