Description

Overview

This trailer pressure protection valve helps protect critical air brake circuits on heavy trailers by isolating auxiliary lines if pressure drops. It stays closed until system pressure builds to about 70psi, then opens to feed downstream components such as suspensions or accessories. As a result, primary reservoirs retain pressure so the driver keeps reliable braking even if an auxiliary circuit fails.

Features

Firstly, the normally closed pressure protection design keeps the main supply safe until system pressure reaches the opening threshold. Additionally, a built in filter helps reduce contamination before air reaches downstream valves and components. Furthermore, matched 1/4″ NPT inlet and outlet ports simplify plumbing into existing manifolds and pipework. Finally, the compact body suits tight mounting spaces along trailer chassis rails.

Specifications and Materials

Operating pressure is set to open at approximately 70psi so auxiliary circuits only receive air once the primary system is charged. Inlet and outlet connections use 1/4″ NPT female ports for straightforward integration into typical trailer air lines. This valve functions as a normally closed pressure protection unit that opens at the set point and closes again if supply pressure falls below that level. A built in filter element helps limit particulate ingress into the auxiliary circuits and downstream valves. Part number: AB8431. For general design principles and operation of pressure protection valves in heavy vehicle air brake systems, see this air brake handbook for more detail.

Compatibility and Fitment

This valve suits trailer air systems that require a single in line pressure protection device between the main reservoir and auxiliary circuits for suspensions, lift axles or accessory feeds. This cross-reference listing means this valve is a suitable replacement for the part numbers and applications shown. Some changes in air line plumbing may be required. WM778A, 118181

Compliance and Safety

Correct use of a trailer pressure protection valve supports compliance with heavy vehicle air brake design requirements by helping preserve primary reservoir pressure for service brakes. In addition, technicians should install the valve in clean pipework and torque fittings to the recommended values to minimise leaks. After installation, always leak test the circuit and verify opening and closing performance as part of standard brake safety checks.

Trailer Applications

This trailer pressure protection valve suits road trailers and dollies that feed air from the main reservoir to auxiliary systems while protecting the brake supply. Additionally, it fits applications where operators want to prevent a failure in one auxiliary branch from draining the entire system. In many fleets, it is used in suspension supply lines, lift axle controls and accessory circuits where pressure protection is essential.

Cross-reference and Suitability

This part cross-references to or suits the following equivalent part numbers and compatible alternatives:

For workshop use, these cross-reference numbers assist with matching existing components during trailer brake maintenance or upgrades.

Why Choose ICS Trailers

ICS Trailers focuses on heavy trailer parts, so you get components selected for Australian road conditions and fleet requirements. Moreover, our team supports workshops with practical information to help match air brake valves to specific trailer layouts. For more compatible fittings, valves and hardware in the same family, Browse Air Brake Parts at ICS Trailers