Disc Brakes - How They Stop Your Semi-Truck

How Disc Brakes Work

It typically takes about two football fields, or two hundred yards, worth of distance for a semi-truck to come to a complete stop. That said, the air brake system is one of the most important systems on your heavy-duty vehicle. Brakes that are out of adjustment are the cause half of all out-of-service violations given to commercial vehicles.

The trucking industry is moving toward disc brakes in an effort to provide stability and uniform braking, which helps all of the components of your air brakes last longer, thus lowering maintenance costs. As well, disc brakes service intervals are typically longer than with drum brakes, and technicians can change them 25% of the time it takes to replace a brake drum shoe.

Brake discs are a large part of your semi-truck's braking system. This means that they are one of the components that need to be checked regularly when you are going over your checklist.

If you've ever wanted to do a deep dive into the ins and outs of brake discs, you've come to the right place! Our team of trucking specialists has put together the following guide to make sure you have all the information you need to ensure your discs are up to par. Read on to learn more about disc brakes!

What Are Disc Brakes?

Disc brakes are designed to provide enhanced safety by offering shorter braking distances over drum brakes. When a truck is equipped with a disc brake system, it is typically able to stop 25 to 30 feet shorter than systems with drum brakes, depending on tires, speed, and road conditions.

There are three types of disc brakes available today: cross drilled, cross slotted, and wave/pedal. A cross drilled system has holes cross drilled on the disc that work to reduce the amount of gas and heat the system produces while also helping to lessen the amount of brake fade. With a cross slotted system, shallow channels are cut into the surface of the disc cut to varying widths and angles. A wave disc, also known as a pedal, uses a wavy cut on the surface of the disc to provide extra gripping surface when stopping.

While each of these disc types have their own merits, you'll have to check your truck to decide which is right for your specific purposes. The closer the product is to manufacture specifications, the better performance you'll get from your air brake system.

How Do Brake Discs Work?

Brake discs, along with brake calipers and brake pads, all work together to bring your commercial vehicle to a stop when you press the brake pedal.

The disc brakes in your semi-truck include, a brake chamber, an eccentric lever, a power screw, brake pads, and a rotor. When the tires are in motion, the rotor moves as well. As the brake pedal is applied, compressed air travels through the brake chamber where the eccentric lever activates the brake force. The power screw then pushes up against the brake pads, clamping them down on either side of the rotor, generating the friction needed to slow the vehicle down and eventually come to a stop.

When To Change Your Brake Discs

Brake discs typically last from about 80,000 – 120,000 miles before they need to be changed. Constant friction from the brake pads wears down your brake discs, so It's important to make sure they are replaced when necessary. It's recommended that you change your discs when they fall below the minimum thickness determined by the manufacturer of your heavy-duty truck. A good rule of thumb is to check your discs if your steering wheel wobbles when you press down the brake. It's also a good idea to check the discs when the brake pedal becomes loose, and performance is noticeably reduced.

Shop Brake Discs Today!

Now that you know more a little bit more about the brake discs in your air brake system, the next step is to find the right one for your semi-truck's needs. With a full selection of disc brakes for you to choose from, we are thrilled to be your one-stop shop for everything semi-truck.

Do you want to learn more about the air brake system in your heavy-duty truck? If so, you'll definitely want to look through our posts on air brake maintenance, brake chambers, brake drums, slack adjusters, and brake shoes.