303.02.0020-S Multi-circuit Protection Valve — KNORR-BREMSE

The multi-circuit protection valve is a critical component within the pneumatic brake system of heavy commercial vehicles, designed to regulate air pressure across different circuits and protect the system from pressure drops. This component ensures that even if one circuit fails, the others remain functional to maintain braking capability.

303.02.0020-S is the OE-equivalent of the KNORR-BREMSE AE 4510S S multi-circuit protection valve used in heavy commercial vehicle brake systems. This high-strength component features multiple M22x1,5 VOSS ports (Ports 1 through 26) and is engineered to meet strict technical requirements for opening and closing pressures, specifically designed for compatibility with KNORR-BREMSE systems.

Workshop technicians should ensure that all port connections (Port 1, 21, 22, 23, 24, 25, and 26) are properly seated using the M22x1,5 VOSS standard to prevent air leaks. The valve operates with an opening pressure of 9 BAR for circuits 21/22 and 23, and a closing pressure of 4,5 BAR for circuit 24. Regular inspection of the pneumatic lines and ensuring no debris enters the ports during installation is essential for maintaining long-term reliability in heavy-duty environments.