303.02.0008 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. It is engineered to distribute supply pressure to four independent circuits—typically covering front brakes, rear brakes, spring brakes, and auxiliary lines—while isolating any circuit that experiences a sudden pressure loss to maintain overall braking integrity.

Vehicle and system compatibility

The component is compatible with DAF, Iveco, and MAN vehicles, ensuring stable performance in demanding service environments. It functions effectively within Knorr-Bremse systems and is designed to maintain high-strength operation under standard braking loads.

Technical specifications and installation

For professional installation, technicians should verify the port connections: Port 1 utilizes an M22x1.5 thread, while Ports 21 through 24 utilize M16x1.5 threads. The unit operates at a maximum pressure of 20 BAR and features specific opening pressures ranging from 6.9 BAR to 7 BAR depending on the circuit, ensuring precise pneumatic regulation.

Maintenance and troubleshooting

Regular inspection of the valve housing and connection seals is recommended to prevent air leaks. If pressure drops are detected in specific circuits, this unit should be checked for internal diaphragm integrity or port blockage to ensure continuous safety for the vehicle.

OE cross-reference

303.02.0008 (4-circuit protection valve) is the equivalent of the DAF, Iveco, Knorr-Bremse and MAN OE numbers. This part directly replaces DAF OE numbers 1519373, 1521199. It also replaces Iveco OE number 97166254, Knorr-Bremse OE number AE4613 and MAN OE numbers 81521516093, 81521516096, 81521516097.