Description

Overview

Pressure protection valve Mack applications rely on this compact valve to protect the primary brake air supply when auxiliary circuits draw too much air or fail. Consequently, it keeps reservoir pressure at a safe level so trailers and trucks maintain braking performance under demanding conditions. In addition, it helps isolate non-critical circuits so the driver still has service brakes even when accessories leak or malfunction.

Features

• Firstly, fixed pressure settings open at 85psi and close at 70psi to prioritise brake reservoirs.
• Additionally, 1/4in NPT inlet and outlet ports allow straightforward plumbing into common air brake layouts.
• Moreover, the compact air brake pressure protection design suits many Mack truck and trailer configurations.
• Finally, technicians can service the valve using standard heavy vehicle air brake maintenance practices and test procedures.

Specifications and Materials

This pressure protection valve Mack compatible unit works in heavy vehicle air brake systems where a normally closed valve opens only after system pressure reaches a safe level. Therefore, primary reservoirs receive protection before air flows to secondary or accessory circuits.

Inlet port: 1/4in NPT. Outlet ports: 1/4in NPT. Nominal opening pressure: 85psi. Nominal closing pressure: 70psi. The overall configuration aligns with PR-4 style pressure protection valve layouts often used on Mack vehicles and related trailer combinations.

Part number: AB8494.

For general background on how pressure protection valves operate in air brake systems, refer to this manufacturer technical guide

Compatibility and Fitment

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. 032222, 20QE2326A, 25165589, LPR3712, LPR-3712, 170.16100V, 918330, MAK20QE2326A.

Compliance and Safety

Before any work starts, technicians must isolate and fully drain the air system so all reservoirs depressurise safely. Next, they should install the valve in accordance with the vehicle manufacturer’s air system schematic, then torque fittings to the correct specification.

After installation, they should pressure test the circuit, verify that the valve opens and closes at the expected pressures, and check for external leakage using an approved leak-detection method. As a result, the service brake supply remains protected and the system continues to meet heavy vehicle safety expectations.

Trailer Applications

This pressure protection valve Mack compatible unit suits on-highway trailers and rigid vehicles where accessory circuits such as suspension, auxiliary tanks or ancillary equipment must not rob pressure from the primary brake system. Furthermore, it fits many Mack based trailer and truck combinations that specify a pressure protection valve with 1/4in NPT ports.

Workshops can use it during brake system repairs, trailer refurbishments or air system upgrades where a reliable protection valve is required to safeguard the main reservoirs.

Cross-reference and Suitability

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

Why Choose ICS Trailers

ICS Trailers sources proven heavy vehicle components and backs them with practical product knowledge for workshops and fleet operators. In addition, you get clear technical data, competitive pricing and access to a wide range of compatible air brake parts from one supplier.

For more air brake components suited to similar systems, browse our Air Brake Parts range at ICS Trailers