How Do Air Brakes on a Semi-Truck Work? What You Should Know

When your career focuses on driving a semi-truck, it involves safety practices and regular maintenance. However, air brakes can be a good alternative when your brakes don’t function as they used to. Let’s learn how air brakes work in semi-trucks.

What Are Air Brakes?

Air brakes in commercial semi-trucks or motor vehicles use compressed air, pushing the brake shoe lining onto the brake drum. It creates friction to slow the wheel and come to a halt. Effective air brakes allow oversized vehicles weighing thousands of pounds to come to a safe, complete stop. Instead of relying on hydraulic brake fluid, air brakes constantly produce compressed air. They are among the most important components in semi-trucks and other commercial vehicles.

How Semi-Truck Air Brakes Work

Air brakes operate in semi-trucks using compressed air when the driver presses the brake pedal. The compressed air pumps into air storage tanks beneath the truck, through air brake lines, and eventually to the air brake. Next, air flows through a nozzle to the brake chamber, causing brakes to move a component called an “S-cam.”

The “S-cam” forces the brake shoe linings away from themselves, pressing them inside a brake drum to create the pressure and friction needed to slow the wheel. When releasing your foot from the brake pedal, the “S-cam” starts to rotate back, causing springs to pull the brake shoes away from the brake drum, eliminating friction.

Reasons Semi-Trucks Use Air Brakes

Why do semi-trucks use air brakes? Air brakes produce constant air throughout the system, while hydraulic fluid requires refills and can potentially leak. This can create a safety hazard for semi-truck drivers and result in major repairs or replacements.

Operating a semi-truck requires exceptional parts that keep it running for years. At Van Horn Truck Parts, we provide high-quality aftermarket semi-truck and trailer parts at competitive prices. Our high-quality truck air valves can keep your truck’s air brake systems optimal and functional for long treks and heavy-duty cargo transports. Contact us today if you have any questions about our truck and trailer aftermarket parts.