Wabco 4757001220 Automatic Load Sensing Valve

Description

The Wabco 4757001220 is an Automatic Load Sensing Valve, a critical component in trailer air brake systems. It's designed to regulate air pressure to the trailer brakes based on the load, ensuring optimal braking performance and stability. This valve is commonly used in heavy-duty trucks and trailers to improve safety and control. The valve features a break point of 0.4 bar, an operational range of 1.0 to 4.6 bar, and a regulating ratio of 1:8. It's constructed to OE specification, offering reliable and consistent performance under various operating conditions. The valve measures 311 x 179 x 109 mm and has port threads of M22 x 1.5 (x2) and M12 x 1.5. It operates dynamically within a temperature range of -40°C to +80°C, ensuring consistent function even in extreme climates.

Key Features & Benefits

This valve basically figures out how much weight is in your trailer, and then adjusts the air pressure going to the trailer brakes accordingly. It does this with a mechanical linkage – usually a rod that runs from the trailer’s spring suspension up to the valve. As the trailer gets heavier, the springs compress, and that movement tells the valve to send more air to the trailer brakes. It's a purely mechanical system, no electronics involved. It’s a key part of your trailer brake control system. Think of it like this: the tractor protection valve sets the maximum air pressure going to the trailer brakes, but this valve fine – tunes it based on how much load you're carrying. Without it, your trailer brakes might be too weak when fully loaded, or way too strong when empty – creating a safety hazard and wearing out your brakes prematurely. It ensures proportional braking, meaning the trailer brakes apply with the right amount of force for the weight it’s carrying.

Symptoms, Risks & Replacements

It's absolutely vital for safe and effective trailer braking. You'll notice if this valve goes bad, because your trailer’s braking will feel off – either not strong enough to stop reliably when loaded, or grabbing and skidding when empty. It prevents trailer sway, reduces stopping distances, and generally keeps you much safer on the road. It’s one of those things you don’t think about when it’s working right, but you’ll definitely know if it isn’t. If you're looking to replace one, you can find a good selection over at Fixparts Online, but any reputable truck parts supplier will carry them. Just make sure you get the right one for your setup.

Warranty Information

Wabco Automatic Load Sensing Valve (MPN 4757001220) comes with a 1-year warranty.