Heavy-duty truck brake technology has advanced over the years and continues to be an important safety feature for trucks.
There are two types of air brakes: disc brakes and drum brakes. Though both types use the same principles of friction to slow a vehicle down, air disc brakes have many advantages over drum brakes.
The trucking industry is trending toward air disc brakes because of safety, efficiency, and in some situations, a lower total cost of ownership. Disc brakes enhance safety by providing shorter stopping distances than drum brakes and improving trailer in-line braking stability. The stopping distance for disc brakes can be 25 to 30 feet less than drum brakes, depending on tires, speed, conditions and the braking system on the tractor. The stopping power is noticeably greater when both the tractor and trailer are equipped with air disc brakes, particularly when the vehicle is traveling at increased speeds.
HOW AIR DISC BRAKE WORK?
Reliability is essential for brake calipers in commercial vehicles – with no compromises! Air Disc Brakes and rationalized Calipers are some of the most heavily loaded components in trucks, buses and trailers and are subjected to enormous forces. Braking systems in commercial vehicles develop clamping forces of over 25 tonnes and are exposed to temperatures of over 900 degrees and vigorous movements up to 25 times stronger than the force of gravity. In addition, they also face vibrations, cold, moisture, dust and dirt.
Disc brakes have friction pads that float inside the caliper adjacent to a large metal disc called a rotor. Instead of a brake drum attached to the wheel hub, a rotor is attached to the hub. A caliper is contained on the brake carrier with its own brake chamber. When the brake is applied, the caliper squeezes the brake pads against the rotating rotor, slowing the wheel. Since the rotor is exposed to outside air, it is able to cool quickly, which decreases its tendency to overheat or cause fading.
Air brakes on trucks work using compressed air instead of hydraulic fluid. Air brakes can be either drum brakes or disc brakes, or a combination of both.
Air is pressurized by an engine-mounted compressor. The air compressor then pumps the air into the air storage tanks, which store the compressed air until it’s needed.
Air pressure is used to apply the service brakes and release the parking brake. There are multiple air circuits in the system. The parking brake engages by spring force in the parking brake portion of the spring brake chamber when the air pressure in the chamber is released.
This also allows the parking brake to be used as the emergency brake system. If air pressure was to drop too low, the force exerted by the spring in the chamber will be able to overcome the force exerted by the air on the diaphragm and apply the brakes on all wheels.
You might think of air brakes as working similarly to a hydraulic brake circuit. As with hydraulic brakes, when the driver presses the brake pedal, air pressure is applied, like hydraulic pressure in a hydraulic brake circuit to the wheel when applying the brake.