Heavy-Duty Air Brakes Explained
Rather than using brake fluid like light-duty trucks and passenger vehicles, heavy-duty trucks use compressed air to activate their brakes. Using a large air compressor that’s mounted to your engine, the air is compressed and stored in different air tanks. From here, the air is sent through an air dryer to eliminate moisture from the air. To get compressed air to each brake, it must first go through a series of valves and controllers to ensure each brake gets an appropriate amount of compressed air.
The Brake Mechanisms
The brake mechanisms in a heavy-duty truck are far more complicated than that of light-duty trucks and passenger vehicles. To start the process, compressed air is pumped into a service chamber that can be found within each brake assembly. Inside this chamber, the compressed air pushes on a diaphragm. This diaphragm is connected to a push rod, which is, in turn, connected to a clevis and your brake adjuster. When these components start to move, they rotate a shaft connected to the bottom of your brake adjuster. This shaft has a metal bracket on its end that moves two brake shoe bolts, which in turn causes the brake shoes to expand, and allows for your brake pads to press against your brake drum.
Brake Adjusters Explained
Your brake adjusters are designed to automatically take up slack as wear on your brake pads increases. This means your push rod won’t have to travel too far when brake pressure is applied, therefore making it easier on your brake assembly as a whole. It’s important to get your brake adjusters calibrated on a regular basis in order to ensure they’re working properly.
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