303.02.0073 Volvo Compatible 4-Circuit Protection Valve

What does a 4-circuit protection valve do?

This 4-circuit protection valve serves as a critical component within the pneumatic brake system of heavy commercial vehicles. Its primary function is to distribute supply pressure to four independent circuits—typically covering front brakes, rear brakes, spring brakes, and trailer supply—while isolating any circuit experiencing a pressure loss to maintain overall system integrity.

Compatible Volvo models and engines

The valve is designed for compatibility with Volvo models including the F10 (TD102), F12 (TD122), FL10 (TD103/D10A), FL12 (TD123), NL10 (D10A), NL12 (D12A), B10B (D10A), B10M (D10A), and B12 (D12A). It is also fitted to Mercedes-Benz trucks. This component ensures consistent air pressure management across diverse heavy-duty applications.

Technical specifications and installation

Technical specifications include an M22x1.5 inlet port and M16x1.5 outlet ports for circuits 21 through 24. The valve operates with an opening pressure of 6.5 BAR and a closing pressure of 4 BAR across all four circuits. When performing maintenance, technicians should verify port dimensions and pressure settings to ensure exact match with the existing installation.

Maintenance and system integrity

For optimal performance, ensure all connections are secure and free from contaminants that could affect the internal check valves. Regular inspection of the pneumatic lines connected to this valve can help prevent pressure drops in the braking system.

OE cross-reference

303.02.0073 (4-circuit protection valve) is the equivalent of the Knorr-Bremse, Mercedes-Benz and Volvo OE numbers. This part directly replaces Knorr-Bremse OE numbers AE4168, I75300, K019911N00. It also replaces Mercedes-Benz OE number 0014315906 and Volvo OE numbers 1130617, 1593150.