303.02.0004 Multi-circuit Protection Valve — WABCO

The heavy-duty multi-circuit protection valve serves as a critical component within the pneumatic braking system of heavy commercial vehicles. Designed to regulate air pressure across multiple circuits, this component ensures that even if one circuit loses pressure, the others remain operational to maintain vehicle control. It is constructed with high-strength components to withstand the rigorous vibrations and pressure fluctuations inherent in long-haul transport.

303.02.0004 is the OE-equivalent multi-circuit protection valve used in DAF, Mercedes-Benz, VDL, and Alexander Dennis vehicles. It is fully compatible with WABCO systems, specifically meeting the technical requirements for parts such as 934 705 003 0 S and 934 705 005 0 S. This ensures seamless integration into existing brake architectures for workshop technicians performing maintenance or system overhauls.

Installation requires strict adherence to port specifications to prevent leaks. The unit features Port 1 through Port 26 with M22x1,5 threads and Port 27 and Port 28 with M12x1,5 threads. Workshop professionals should verify the opening pressures—7,5 BAR for circuits 22/24—and closing pressures—7 BAR for circuits 21/22—to ensure the component matches the original vehicle specifications before assembly.

Regular inspection of the pneumatic connections and checking for any pressure drops in the secondary circuits is recommended during routine service intervals. Maintaining these high-grade components ensures the long-term reliability of the vehicle's braking performance and overall safety during heavy-duty operations.