303.02.0074 4-circuit protection valve — KNORR-BREMSE

This 4-circuit protection valve serves as a critical component within the pneumatic brake system of heavy commercial vehicles. Its primary function is to isolate circuit failures, ensuring that even if one pneumatic circuit loses pressure, the remaining circuits maintain sufficient functionality to ensure vehicle control and safety. Constructed with heavy-duty grade materials, this component is engineered to withstand rigorous operational environments.

303.02.0074 is the OE-equivalent of the KNORR-BREMSE AE 4169 4-circuit protection valve used in professional braking systems. The unit features a primary port of M22x1,5 and four secondary ports (21, 22, 23, and 24) measuring M16x1,5 each. The opening pressure for all four circuits is set at 7 BAR, while the closing pressures are calibrated at 4,2 BAR for circuits 21 and 22, and 5,5 BAR for circuits 23 and 24.

Workshop technicians should ensure that all connections are seated correctly to prevent pneumatic leaks. When performing maintenance or replacement, verify that the port sizes match the existing installation to maintain system integrity. Proper installation of this valve is essential for maintaining the correct pressure differential required for safe braking performance in heavy-duty applications.