Description

Overview

The Sealco relay valve 6 port delivers fast, consistent control of trailer service brakes in heavy vehicle air brake systems. It sits close to the brake chambers, so it reduces brake lag and helps apply rear brakes in step with the tractor. As a result, fleets and trailer builders gain more stable braking and smoother control under load. In addition, the compact 6 port layout supports multi-axle plumbing without unnecessary tees or fittings.

Features

This relay valve focuses on reliable service operation in demanding trailer environments. Firstly, the 3/4″ NPT supply port provides high air volume from the reservoir. Secondly, the six 3/8″ NPT delivery ports give flexible routing options to multiple brake chambers. Additionally, a dedicated 3/8″ NPT control port lets the valve respond quickly to foot valve signals for balanced braking. Finally, the body design suits typical trailer and semi-trailer mounting positions, so installers can position the valve for clean airline runs.

Specifications and Materials

This relay valve uses a 3/4″ NPT supply port, six 3/8″ NPT delivery ports and a 3/8″ NPT control port to match common heavy trailer air brake layouts. Internal passages are sized to support service brake pressures used in multi-axle road trailers, while the porting pattern helps keep hose runs short and direct. Part number: AB8459.

For a technical explanation of how relay valves operate within air brake systems, see this relay valve technical overview which describes the general function and role of relay valves in heavy vehicles.

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. 116451

When selecting a Sealco relay valve 6 port, match the supply size, delivery port count and control port size to the existing installation. Additionally, check mounting orientation and nearby clearance so the valve can exhaust cleanly. In addition, use compatible thread sealant on all NPT connections and always pressure test the system after installation.

Compliance and Safety

Correct use of a Sealco relay valve 6 port supports compliance with heavy vehicle braking performance requirements, provided the valve is installed into a correctly engineered system. Installers should follow all relevant workshop practices, torque values and leak-check procedures. Furthermore, any replacement must maintain original design intent for axle groups, brake balance and trailer load ratings. Always isolate, drain and lock out the air system before removal or installation, then confirm proper brake operation in a safe test area.

Trailer Applications

This relay valve suits on-highway semi-trailers, dog trailers and similar equipment that use air-operated service brakes. Typically, it mounts near the rear axle group so the valve can feed chambers on multiple axles through the six delivery ports. Moreover, the 3/4″ NPT supply connection matches common reservoir plumbing on heavy trailers, which simplifies upgrades from older valves. As a result, the valve helps maintain consistent braking response across loaded and unloaded conditions when paired with a correctly configured air brake system.

Cross-reference and Suitability

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

Before finalising any replacement, verify that the control signal, supply line and delivery port locations suit the existing hose layout and that the valve’s operating characteristics are appropriate for the trailer’s brake design.

Why Choose ICS Trailers

ICS Trailers focuses on practical, workshop-ready air brake solutions for heavy trailers. Our team works daily with operators, repairers and trailer builders, so we understand how important reliable valves are to uptime and compliance. Consequently, we select proven components and back them with clear technical detail, straightforward advice and responsive support. In addition, stocking compatible fittings and related air brake parts makes it easier to complete the job in one visit.

Browse more Air Brake Parts at ICS Trailers in our Air Brake Parts category