Description

Overview

The FF-2 full function relay valve combines relay, spring brake and quick release functions in one compact body for trailer air brake systems. It manages reservoir, service and spring brake ports so the trailer brakes respond quickly and consistently. As a result, it simplifies plumbing compared with separate relay and spring brake valves. Additionally, it helps reduce the number of joints and potential leak points in the system.

Features

This full function relay valve prioritises service brake control so available tank pressure goes to stopping the vehicle first. Additionally, built in pressure protection prevents the spring brakes from releasing until reservoir pressure reaches a safe level. Furthermore, the heavy duty mounting nipple and corrosion resistant treatment support harsh trailer environments. In addition, integrated quick release ports help the service and spring brakes release cleanly.

• Single valve layout for easier installation and troubleshooting
• Built in service and spring brake quick release functions
• Service brake priority for safer stopping performance
• Suitable for single or twin air tank trailer systems

Specifications and Materials

This valve suits air brake trailers that require a 3/4 inch NPT reservoir port feeding 3/8 inch NPT delivery ports. The design includes a 3/8 inch NPT supply port, a 1/4 inch NPT control port and two 3/8 inch NPT spring brake ports, with a crack pressure of 3 PSI to match common full function valve settings. Part number: AB8434. For a deeper explanation of full function trailer valves and their role in trailer air brake systems, refer to this full function valve service literature

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. N4304AC, EMDKN28600X, MIDKN28600, HDX KN28600, 300479CC, N4304, N4304AG, N4304AK, N4304BA, S8664, 5396-KN28600, 12352, PL-28600, RB-28600, 110742, 110744, 401221, 39300584, FF2, JNY0859, EM40750.

Compliance and Safety

The FF-2 full function relay valve is designed to support trailer air brake systems that must meet FMVSS 121 performance requirements when used in a correctly engineered circuit. Consequently, the built in pressure protection and anti compounding behaviour help protect foundation brake components from damage caused by overlapping service and spring brake forces. Always follow the trailer or axle manufacturer’s plumbing diagrams and test all circuits for leaks and correct timing before returning a vehicle to service.

Trailer Applications

The FF-2 full function relay valve suits common semi trailer, dog trailer and pig trailer brake layouts where a single valve controls both service and spring brakes. Additionally, it can be used with either single or twin air tank configurations when matched to the correct reservoir size and piping. As a result, workshops can standardise on one valve style for many highway trailer applications.

Cross-reference and Suitability

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

Always confirm port sizes, crack pressure and mounting layout against the removed valve and the trailer brake schematic before final installation.

Why Choose ICS Trailers

ICS Trailers focuses on supplying proven air brake components that match heavy trailer requirements, backed by practical product knowledge and local support. For more related components, Browse Air Brake Parts at ICS Trailers