Wabco 4802020090 Proportional Relay Unit

Description

The Wabco 4802020090 Proportional Relay Unit is a critical component within air brake systems, specifically functioning as a relay valve to regulate air pressure and control braking functions in commercial vehicles. This unit is designed for demanding applications requiring precise and reliable brake modulation. Measuring 156 x 124 x 158 mm, this device features M22 x 1.5 JED-388-4 port threads, a bayonet electrical connection (DIN 72585), and is built to withstand harsh environments with its IP 6K6K / IP 6K9K protection class. Its robust design, combined with a wide operating temperature range of -40°C to +80°C, ensures consistent performance and extended service life.

Key Features & Benefits

Basically, this thing takes a low – pressure signal from your vehicle’s computer—think of it as a whisper—and boosts it into a much stronger air pressure signal to operate your air brakes. It’s controlling how much air gets sent to the brake chambers on your axles. It doesn’t make the brakes work, it’s the muscle behind the signal, if you will. It’s also handling things like trailer supply air and spring brake activation, depending on the system. It’s really a central point for air brake control. It sits right in the air brake system, acting like a translator and amplifier between the electronic controls and the actual air brakes. It's a key component in systems that need precise brake force control, like those found on larger trucks and trailers where ABS and stability control are involved. It receives information about how hard you're asking the brakes to work, then it modulates the air pressure accordingly. It’s often part of the ABS system, so those two work closely together.

Symptoms, Risks & Replacements

If this unit fails, you'll likely notice if you have a trailer. Brakes might not apply evenly, or you might have issues with the spring brakes engaging unexpectedly. On a tractor unit, you could see issues with overall braking performance and ABS function, maybe even a warning light on the dash. It's a safety item, plain and simple. A faulty relay could lead to reduced stopping power, or worse. You can find these pretty easily; we carry a good selection at Fixparts Online, and there are other sources of course. But it's a part you want to keep in good shape.

Warranty Information

Wabco Proportional Relay Unit (MPN 4802020090) comes with a 1-year warranty.