How Brakes Work – A Guide to Disc and Drum Brakes

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There’s no safety system on a vehicle more important than the braking system. This system helps slow down the rotation of the wheels when the brake pedal is depressed, ensuring a vehicle comes to a complete stop.

There’s a lot going on within a braking system during this process. Keep reading to learn more about the different types of systems, the parts they include and how they work.

Types of Braking Systems

Braking systems in passenger vehicles use two primary types of brakes: disc brakes and drum brakes. While they both bring a vehicle to a stop, they differ in design and operation.

Disc brakes are the only type used in the front of vehicles but may be found at all four wheels. All passenger vehicles made and sold in the United States will have disc brakes on the front and possibly the rear as well, while drum brakes will only be found on the rear of U.S autos.

Drum Brakes

Drum brake systems were the first in-tire systems introduced, released in 1900 and patented in 1902 by engineer Louis Renault. While the first designs were completely mechanical and used levers to operate, by the mid-1930s they were applied using hydraulic pressure.

This system consists of a master cylinder that sends pressurized brake fluid to the wheel cylinder located inside the brake drum. This pressure causes the pistons in the cylinder to expand and press the brake shoes against the inner surface of the brake drum, which creates friction to help slow the spinning of the wheels.

Disc Brakes

While disc brakes were patented the same year as drum brakes, it took almost half a century for the designs to become practical and cost-effective for use in automobiles.

The superior performance over drum brakes was first realized by Jaguar in 1953, when they used them on a race car that triumphed over other cars using drum brakes. Later that same year, a production car was sold with all disc brakes. Since then, they’ve been considered the standard for most vehicles.

This system consists of a master cylinder that sends pressurized brake fluid to the brake caliper, causing its pistons to press against a steel rotor disc, creating friction to slow the spinning of the wheels.

Drum vs. Disc Brakes

While drum brakes have their place, they also have disadvantages when compared with the disc type. Manufacturers have come to prefer the disc braking system because of its many advantages, which include:

• Cleaning: Unlike drum brakes, which need periodic cleaning due to brake dust collecting on the shoes, disc brakes are self-cleaning. This is thanks to the brake pads wiping against the rotors when they’re engaged, effectively cleaning themselves.
• Consistent performance: Disc brakes are better at managing heat than drum brakes. Drum brakes are likely to get hot with repeated use and experience brake fade, which can result in a vehicle needing a greater distance to stop safely.
• More stopping power: Advancements in technology have made disc brakes more durable and better equipped to bring a car to a stop faster.
• Handling during wet conditions: Disc brakes are open to the air, meaning water can come off easily. This makes them better at performing during wet conditions, as drum brakes have the tendency to trap water.

Parts of the Braking System

Every part in a braking system plays a key role in the stopping process. While disc and drum brakes have some similar parts, they do differ quite a bit.

Drum Brake Parts

The drum brake system consists of the master cylinder, wheel cylinders, primary and secondary brake shoes, multiple springs, retainers, and adjustment mechanisms.

When it comes to how long these parts last, a lot of variables come into play. Typically, the drum brake housing (the drum itself) is designed to last between 150,000 and 200,000 miles. Brake shoes have a lower lifespan depending on use, usually anywhere between 35,000 to 60,000 miles.

Disc Brake Parts

Major parts of a disc brake system include the master cylinder, caliper, rotor and pads.

How long do disc brake pads last? The answer to this varies based on a range of factors, including how much pressure is applied during the stopping process and how often they’re used. Automotive technicians usually estimate most vehicles will get between 25,000 to 65,000 miles for brake pads and 30,000 to 70,000 miles for brake rotors.

The best thing to do is just pay attention to how your car feels during the braking process and getting the system checked out on a regular basis to catch problems early.

Signs Brake Parts Are Wearing Down

There are several indicators of problems with different parts of the braking system. It’s important to get your car checked when you notice these things to ensure you get any necessary repairs done:

• Vibrations in steering wheel: If you start to feel vibrations when applying the brakes, it can be a sign of uneven rotor wear. Warping on the surface of the rotors can cause this.
• Having to press the brake pedal down hard to stop: Different parts of the braking system can wear down and require more of an effort when bringing your car to a stop. If you’re having to press down farther or the pedal feels spongy, it can be an indicator of wear.
• Loud noises: Any odd or loud noises coming from your braking system might indicate different parts are wearing down. Screeching, grinding or squealing can be indicators of wear and tear on brake pads or shoes.
• Car pulling to one side: When you step on the brakes, you might notice that your car is pulling to one side. Brake pads starting to wear unevenly can cause this.
• Brake light: If your dashboard brake light comes on, be sure to take your car to an auto tech to get it looked at right away.

Work on Braking Systems as an Automotive Technician

Pursuing a career as an automotive technician can help give you the opportunity to learn all about brake systems. The skilled trades are growing — total auto technician employment is expected to be 743,800 by 2031.47 Training as an automotive technician at Universal Technical Institute (UTI) can give you the hands-on experience employers are looking for when hiring.1

Courses taught over UTI’s 51-week Automotive Technology program cover a range of topics for the role, including a section about vehicle braking systems. You can graduate in less than a year ready for an entry-level position in the industry!7

Interested in finding out more? Request more information, or call 800-834-7308 today!

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