Wabco 4757120040 Automatic Load Sensing Valve

Description

The Wabco 4757120040 Automatic Load Sensing Valve is a critical component in air brake systems, automatically adjusting braking force based on vehicle load. This valve is used in trucks, trailers, and buses to ensure optimal braking performance and stability. Its mechanical design features an actuation angle of -45° to 30°, and operates effectively within a temperature range of -40°C to +80°C. This valve improves safety and control by maintaining consistent braking efficiency, regardless of load variations. It measures 124 x 154 x 313 mm and features ports with M16 x 1.5, M22 x 1.5, and a flap exhaust. This version includes an integrated emergency valve.

Key Features & Benefits

This valve basically monitors how much weight your vehicle is carrying and adjusts the air pressure to the rear brakes accordingly. It’s constantly measuring the chassis deflection – how much your suspension is compressing from the weight. It then proportionally increases or decreases air pressure to the rear brake chambers. Think of it like a smart regulator; it doesn’t just send a fixed amount of air, it adjusts how much air goes to the rear brakes based on the load. It’s a crucial part of your air brake system, specifically designed to prevent wheel lockup, especially when you’re lightly loaded. Older systems, or ones without this valve, apply the same braking force to the rear wheels regardless of weight. That’s a problem because if you’re not carrying much, those rear wheels can easily lock up during braking, leading to skids. This valve makes sure the rear brakes don't overpower the front brakes, maintaining stability.

Symptoms, Risks & Replacements

It's a really big safety item. If this valve fails, you’ll notice if you’re lightly loaded that your rear brakes might lock up before the fronts, and that’s obviously dangerous. Conversely, if it gets stuck in a certain position, you might not get enough braking force to the rear when you are loaded. Proper braking balance is essential for control, and this valve helps achieve that automatically. You can find these relatively easily – Fixparts Online has a good selection, and getting the right one ensures your air brakes work as designed. It's something you definitely don't want to ignore if you suspect it's failing.

Warranty Information

Wabco Automatic Load Sensing Valve (MPN 4757120040) comes with a 1-year warranty.