Wabco 4721950330 Relay Valve

Description

The Wabco 4721950330 Relay Valve is a critical component in air brake systems, specifically designed for trailer brake controls. It functions as an intermediary between the brake pedal and the brake chambers, efficiently translating driver input into braking force. This relay valve is built to OE specification, ensuring reliable performance and durability in demanding applications. Measuring 119 x 111 x 98 mm, it features robust construction with an IP 66 / IP 69 K protection class and operates within a temperature range of -40°C to +80°C. Its key parameters include a break point of 0.3 bar, a calculated volume of 1.2945, and various port thread configurations: 2x 3/4 - 18 NPTF, 4x 3/8 - 18 NPTF, 3/4 - 18 NPTF, and 3/8 - 18 NPTF - JED - 686, as well as M22 x 1.5. The electrical connection is Bayonet DIN 72585 A1-3.1-Sn/K1, and the valve operates at 12 V with a rated current of 2220 mA.

Key Features & Benefits

This thing basically controls the air pressure going to the spring brakes on your trailer. It has a couple of jobs. It’s the main control for applying and releasing those spring brakes, and it also manages the emergency line – meaning if the connection between your truck and trailer gets broken, it’ll automatically apply those trailer brakes. It's like a gatekeeper for the air that operates your trailer brakes. Think of your tractor’s brake system as sending a signal to the trailer. The relay valve is the part that receives that signal and translates it into actual braking force on the trailer. It doesn’t directly control the truck brakes, it’s all about what’s happening back on the trailer axles. It’s a key piece of the whole air brake puzzle – without it, your trailer’s brakes just won't work properly.

Symptoms, Risks & Replacements

This is a safety thing, plain and simple. If it fails, your trailer brakes might not apply when you want them to, or they might drag. You’ll notice if it's failing because you might feel pulling or a longer stopping distance, or the trailer brakes might stick and overheat. It acts like a shield, protecting you from a runaway trailer situation. If you suspect a problem, get it checked immediately. You can find these parts pretty easily – a place like Fixparts Online has a good selection if you want to take a look. But honestly, if you're not comfortable working on air brakes, let a professional handle it. It's not something to mess around with.

Warranty Information

Wabco Relay Valve (MPN 4721950330) comes with a 1-year warranty.