Four-Circuit Protection Valve

1. Basic Part Information

• Part Name: Four-Circuit Protection Valve

• Part Number: LG9700360062

• Main Body Structure: Compact, three-dimensional structure made of cast aluminum.

• Air Line Ports: Four protruding cylindrical outlets on the top (typically connecting to the front brake, rear brake, parking brake, and auxiliary air circuits). A larger inlet on the side (connecting to the air reservoir). A drain valve or auxiliary port at the bottom.

• Control Component: A blue plastic protective cap on the side (usually covering the manual control button for emergency braking or differential braking).

2. Applicable Models & Installation Position

• Applicable Models: Mainly suitable for Sinotruk HOWO light truck series, such as Hanjiang, Tongshuai, and other models.

• Compatible Chassis: Some other light trucks under the Sinotruk brand.

• Installation Position: Mounted near the air distribution unit on the frame rail, or between the air reservoir and brake lines. It is a core distribution component in commercial vehicle air brake systems.

3. Main Functions & Role

• Air Distribution & Protection: The four-circuit protection valve is the "heart" of the multi-circuit air brake system in commercial vehicles. It receives high-pressure compressed air from the air reservoir and distributes it to four independent circuits (typically front brake, rear brake, parking/emergency brake, and auxiliary air circuits such as clutch booster, air horn, etc.).

• Fault Isolation: If one circuit develops an air leak or abnormal pressure, the protection valve automatically cuts off the air supply to that faulty circuit, ensuring the remaining circuits maintain normal brake pressure. This preserves partial braking capability in emergency situations, significantly improving driving safety.

• Pressure Regulation: The pressure ratios for each circuit are preset at the factory (e.g., prioritizing air supply to the brake circuits), ensuring proper responsiveness and stability of the braking system.