303.02.0027 4-circuit protection valve — KNORR-BREMSE

The essential function of this 4-circuit protection valve is to manage pneumatic pressure distribution within the brake system, ensuring reliable air circuit stability for heavy commercial vehicles. Constructed with heavy-duty grade materials, it provides precise control over opening and closing pressures to maintain safety during operation.

303.02.0027 is the OE-equivalent of the KNORR-BREMSE AE 4609 and II37460N00 used in MAN heavy commercial vehicle systems such as models with reference codes 81.52151-6095, 81.52151-6098, 81.52151-6099, 81.52151-6105, 81.52151-6106, and 81.52515-6105. This component ensures seamless integration with compatible pneumatic braking architectures.

For workshop technicians, this unit features a standardized M22x1,5 threading across multiple ports to facilitate straightforward assembly and maintenance. It is designed to operate at a maximum pressure of up to 20 BAR (with a standard operating pressure of 13 BAR), making it a reliable choice for professional servicing of heavy commercial vehicle brake networks.

Regular inspection of the port connections and pressure thresholds—such as the specific opening pressures for ports 21 through 24—is recommended during routine service intervals to ensure optimal pneumatic performance and system integrity.