Brakes are the most vital safety feature in any motor vehicle, but it’s not as easy to stop a commercial truck as it is a sedan. If you’re managing a commercial fleet, understanding how truck brakes work will help you identify when it’s time to call for truck repair services. Here’s what you should know.

A Guide to Truck Brakes

Are truck brakes different from car brakes?

Truck and car brakes both stop vehicles by applying friction and function using brake drums connected to the wheel axles. Car brakes rely on brake liquid to work, which makes them a hydraulic-based system. Trucks, like buses and trains, rely on compressed air brakes instead. 

The main advantage of air-based braking is that, unlike brake fluid, the air doesn’t run out. Even if you have a small leak in the system, the brakes will still be able to function correctly. 

Are there different types of truck brakes?

S-Cam brakes are commonly used in trucks and heavy machinery. When you apply the brakes, air is channeled into the brake chamber, where it moves a pushrod.

The pushrod moves the slack adjuster, which turns the camshaft. Finally, this motion twists the S-Cam, which forces the brake linings into contact with the drum. 

truck repairSome trucks have disc brakes instead of S-Cams. In this system, air pressure initiates the sequence of events just as with the other.

However, a power screw is used instead of an S-Cam. The pressure created by the brake chamber and adjuster turns the screw, which then acts on a brake caliper to squeeze the brake pads and stop the vehicle. 

How can I tell which brakes are best for my needs?

Regardless of the type, your brake system will be affected by your frequency of driving, the quality of parts, weight of loads, and local terrain. For trucks carrying heavier loads on steeper roads, disc brakes provide better resistance against sloping, mountainous terrain. 

If your trucks stop more frequently, spend time off-road, or deal with extreme weather, drum systems with bigger pads are recommended. The larger friction contact surface means the brakes will wear down much more slowly, reducing the frequency of truck repair. 

What should I know about brake maintenance?

With all the long trips a truck makes, maintenance servicing needs to be thorough. The brake linings need to be sufficient enough to still be intact during the next maintenance check.

If they aren’t, the brake disc or drum needs to be replaced. Regularly scheduled inspections are the most dependable way to monitor and maintain brake condition.


If you need brake system services for your fleet, contact Northwest Truck Repair in Kalispell, MT. Since 1972, these experienced technicians have been providing quality truck repair and maintenance, including transmission and engine work. Visit them online to learn more about their services, or call (406) 755-9762 to schedule an inspection.