Lee-Smith Truck Talk: Air Disc Brakes vs. Drum Brakes

In this month of love, we’re going to show some love to brakes! Whether you love air drum brakes or air disc brakes, we think it’s important to know the differences between the two. By knowing what sets the two apart, you’ll be able to make a more informed buying decision. 

Air Drum Brakes

Let’s start with traditional drum brakes. Most of the main brake components mount to the spider assembly, which is mounted to the axle of the vehicle. When the brake pedal is depressed, air travels from the foot valve to the brake chamber, which is converted to a mechanical force causing friction between the shoe and the drum. There are four main components of an air drum brake system: brake shoe, brake drum, brake chamber, and spider assembly. The overall concept is simple; however, reassembling these components during a brake service can be complex and somewhat time-consuming due to the number of moving parts.

Air Disc Brakes

Air disc brakes function very similarly to drum brakes with a few different components. The five main components of an air brake system are the foot valve, brake chamber, caliper, brake pads, and rotors or discs. In an air disc brake application, shoes and drums are being replaced with discs and pads. The disc brakes get their stopping force from a caliper clamping the brake pads against a steel disc or rotor. Air disc brake systems have fewer moving parts compared to the drum brake system making them easier to service. 

Air Drum Brakes vs Air Disc Brakes?

The question now is: which is the better option for your fleet? At the end of the day, air drum brakes and air disc brakes both deserve love! While both of these brakes use the same principle of friction to stop a vehicle, there are noticeable differences between the two. When looking at the stopping distance, air disc brakes take the cake on this one by stopping anywhere from 17% to 33% shorter than drum brakes. This difference in stopping distances can reduce liabilities and the risk of accidents. Now looking at the difference in the longevity of these brakes, air disc brakes again come out on top by lasting nearly twice as long compared to traditional drum brakes. This duration gives you less downtime in the shop and more time on the road. Additionally, the air disc brake system is easier to perform maintenance on in terms of replacing pads. Whether you love one more than the other, our Lee-Smith team is here to answer any questions you may have and help you make the right choice for your fleet.