Description

Overview

The R-12 relay valve vertical delivery ports assembly controls trailer service brakes on long wheelbase heavy vehicles. It acts as a remote valve that reacts quickly to the foot brake signal and sends air directly to the brake chambers near the axles. Consequently, the system applies and releases brakes faster, which improves control and reduces lag through long air lines.

Features

• R-12 style relay valve body with vertical delivery ports for compact trailer mounting
• 4 psi crack pressure that promotes quick, predictable brake response
• High capacity flow path that suits multi-axle trailer brake layouts
• Service, supply and delivery ports sized for common heavy trailer plumbing

Specifications and Materials

Part number: AB8349.
This R-12 relay valve uses a 1/4″ NPT service port for the control signal from the foot valve, a 1/2″ NPT supply port from the trailer reservoir and four 1/2″ NPT delivery ports feeding the service brake chambers. The SCTEG R-12 relay valve vertical delivery ports configuration keeps line runs short from the valve to each axle, which helps maintain even brake timing across the trailer set. Crack pressure is 4 psi, so the valve starts to deliver air early in the pedal stroke for a firm, progressive feel. For further technical detail on R-12 relay valve operation and layouts, refer to this manufacturer technical guide.

Compatibility and Fitment

This valve suits R-12 style trailer relay valve positions with vertical delivery ports on long wheelbase trucks, semi trailers and combinations. 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. 102626, 102166, 102165, 102165X, 102277, 102277X, 107443, 107443X, R955102626, RA86477, N9065, 1J6983, 5X0264, 8X6703, 1660683, 515125, 913766, E2335215, E9180334, 119196201, 25005800001, 59A0620, 10130131, 10130377, 207916, X14476, 2097615, 2335215, 2335216, 2335218, 9180334, 12342, 12343, 12344, 12345, 31A974, 20QE222BP1, 20QE222BP2, 20QE445, 223637, 296694R91, 301146R91, 45193L66, 501330H100, 86824R93, 107442, 1321079, 21079, 724083, 36Z106, 110139, 110412, 110416, 110415, 25D4630A, 504603, 722015001, 8068990, A78882, 722013601, 5006738.

Compliance and Safety

Follow the vehicle or trailer manufacturer air brake schematic when replacing any R-12 relay valve. Firstly, park the vehicle safely, chock wheels and fully drain air from the system before loosening lines. Next, connect service, supply and delivery ports to match the original layout, using suitable thread sealant and torque practices. After installation, leak test every joint, then confirm that the SCTEG R-12 relay valve vertical delivery ports unit applies and releases all trailer brakes evenly during low speed tests.

Trailer Applications

Fleets use this R-12 relay valve on trailers and dollies where long wheelbase layouts would otherwise slow brake response. It suits general freight, tanker, tipper and container trailers that rely on fast relay action near the axles for consistent braking. Additionally, it works in multi-trailer road train sets where relay valves must manage several brake chambers from a single control signal.

Cross-reference and Suitability

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

Technicians should still confirm port sizes, mounting pattern and plumbing layout on the original installation before finalising the changeover.

Why Choose ICS Trailers

ICS Trailers focuses on air brake parts that match real Australian trailer conditions, so you can select relay valves with confidence. Our team understands R-12 relay layouts and can help interpret cross-reference lists when you are updating ageing hardware. Browse the Air Brake Parts category at ICS Trailers.