How Do Car Brakes Work? (2024)

Different Parts of Car Brakes

A brake system is made up of a brake pedal, a brake booster, a master cylinder, brake lines, brake pistons, brake drums or rotors, and friction material. When you ask ‘how do car brakes work?’, you are actually asking how all these parts work together.

Where Are the Brakes in a Car?

Car brakes are located at each wheel of the car. You'll find them right behind the wheels, usually covered by the wheel's metal rim. When you press the brake pedal, it sends a signal to the brakes, causing them to squeeze against the wheel's rotor or drum, which creates friction and slows down the car.

What Happens When You Press the Brake Pedal?

When you step down on the brake pedal, you're signaling to your vehicle that you want to stop. The pedal delivers pressure to the master cylinder, along with help from a brake booster to create the stopping force necessary to slow your vehicle. Once the pressure is at the master cylinder, it's distributed throughout your vehicle and used to deliver even stopping pressure.

Braking Force Is Spread to All Four Wheels

The pressure you generate because of the brake pedal and booster is distributed throughout your vehicle by the master cylinder. The cylinder creates hydraulic pressure in the brake lines that spread to each of the four wheels on your car or truck.

As the pressure reaches each wheel, it presses on a cylinder that activates the friction mechanism to stop your vehicle.

How Does Pressing on a Car Brake Stop the Vehicle?

How Do Car Brakes Work? (1)

It makes no difference whether you're driving a vehicle with drum brakes or disc brakes; each type uses a similar mechanism to slow the vehicle. When people try to imagine how car brakes work, they usually think about the final step in the braking process, where the pads or shoes press down and slow your vehicle.

If you have disc brakes, you have brake pads, and when you have drum brakes, you have brake shoes. Either way, these specialized friction pads are designed to rub against a smooth metal surface and create an incredibly high amount of friction. The brake pads get pressed into rotors that are attached to each wheel hub. As the pads press into the rotors by way of one or more pistons inside the caliper, the wheels slow down until the vehicle comes to a stop. On vehicles with drum brakes, the brake shoes are pressed outward due to the brake pressure, and they rub against the spinning brake drums that are attached to the wheels of the vehicle.

No matter if you have drum brakes or disc brakes, your vehicle relies on hydraulic brake pressure that comes from putting pressure on the brake fluid to force the specific brake material your vehicle uses onto spinning metal surfaces attached directly to the wheels of your vehicle. The process is nearly the same, though the parts on the wheels are different.

How Do Brakes Work on a Disc Brake Vehicle?

Most modern vehicles today come equipped with disc brakes. These brakes are easier to work on, and they are nearly as effective as the older-style drum brakes. Since your vehicle is more likely to have disc brakes than drum brakes, you should know how this style of brake works specifically.

Each brake system has a brake pedal, brake booster, a master cylinder, and brake lines throughout the vehicle, but a disc brake system uses different parts at each of the wheels to stop your vehicle.

At the wheel, you have a rotor that is attached to the wheel, and that spins when the wheel spins. This is the surface you'll press on to slow your vehicle. Rotors are usually made from steel, and sometimes they are slotted or drilled to help them cool faster.

The rotor is surrounded by a brake caliper that includes one or more pistons and a set of brake pads. The caliper presses the brake pads into both sides of your rotor using the pressure generated by the brake booster. When you stop pressing the brake pedal, the caliper retracts away from the rotor and relieves the friction on the rotor so it can spin freely once again. Disc brakes are simple to work on, and often you only have to replace the brake pads to restore reliable stopping power to your vehicle again.

How Do Brakes Work on a Drum Brake Vehicle?

How Do Car Brakes Work? (2)

Drum brakes are similar to disc brakes, but they utilize an enclosed design that keeps dust and debris out more effectively. Just like the rotors, drum brakes have spinning metal drums that rotate along with the wheels on the vehicle. If the drums are forced to slow down, they will slow the wheels down at the same time.

When pressure is sent through the brake line to one of the wheels equipped with drum brakes, the brake cylinders press the brake shoes outward into the rotating drums. The shoes scrape against the rotating drums and force them to slow down. Brake shoes generate tremendous stopping power, and this is why drum brakes are relied upon to stop most large trucks today. Just like with disc brakes, you will have to replace the friction material the most frequently. To maintain smooth braking performance, it's important to replace the brake shoes when they wear out, so make the replacement as soon as possible to get the stopping power you need to drive safely.

Now that you understand how the brakes on a car work, you should understand how to evaluate this brake system of a vehicle more effectively. The brake system of a car or truck is just one of the areas that you must inspect when considering making a new purchase. Learn how to understand brakes, and you will know how to inspect your new vehicle more closely.

You should also consider ordering a car history report to help you learn about past accidents, maintenance, and more details about any vehicle you are considering buying. Get all the information about your next car purchase from the car experts here at GoodCar, and you'll end up with a vehicle you can rely on.

How Do Car Brakes Work? (2024)


How Do Car Brakes Work? ›

Your foot presses the brake pedal. Once this happens, pistons and lines filled with brake fluid, a kind of hydraulic fluid, convert the energy from your foot hitting the brake pedal into mechanical energy that presses on the brake pads. The brake pads are what stop the wheels from turning.

What is the function of the brake in a car? ›

To stop the wheel, friction material in the form of brake pads (mounted in a device called a brake caliper) is forced mechanically, hydraulically, pneumatically or electromagnetically against both sides of the disc. Friction causes the disc and attached wheel to slow or stop.

How do brakes stop or slow a car? ›

When the brake calipers are activated, the disc pads compress against the brake discs or rotors, located inside the wheels of the vehicle. This compression causes friction and eventually slows the vehicle to a stop.

How do brakes work simple? ›

When you press the brake pedal, the hydraulic system is activated. The hydraulic unit then sends brake fluid through the brake hoses into the caliper inducing pressure on the caliper piston. The calipers squeeze the brake pads onto the brake discs, causing friction and slowing the vehicle down.

How do car brakes work for dummies? ›

When the brake pedal is depressed, the hydraulic fluid causes the brake caliper to press the brake pad against the brake disc. The rubbing of the brake pad against the brake disc generates friction, which converts kinetic energy into heat in the brake pad.

How do brakes and brake pads work? ›

The principle of operation is based on New0to11n's law of action and reaction. When pressure is applied to the brake pads, they exert a force in the opposite direction to the movement of the wheels. This force counteracts the kinetic energy of the vehicle and slows it down.

Do car brakes need to break in? ›

The break-in procedure is important if you want your new brakes to perform well. This procedure is also called bedding your brakes. It's when the brake pads deposit an even layer of friction material on the rotors.

How do you break in car brakes? ›

Perform 5 moderate to aggressive stops from 40 mph down to 10 mph in rapid succession without letting the brakes cool and do not come to a complete stop. If you're forced to stop, either shift into neutral or give room in front so you can allow the vehicle to roll slightly while waiting for the light.

What do brake pads connect to? ›

Usually found on the front wheels, disc brakes feature brake pads that press against a disc (rotor) when the brake pedal is applied to stop the vehicle. The pads are attached to a brake caliper assembly that frames the rotor.

Do cars use all four brakes? ›

Every car comes with two front brakes and two rear brakes. Older vehicles typically have drum brakes in both the front and rear. In contrast, modern cars tend to have either disc brakes on all four wheels or disc brakes in the front and drum brakes in the back.

Does a car use all 4 brakes? ›

Every car comes with two front brakes and two rear brakes. Older vehicles typically have drum brakes in both the front and rear. In contrast, modern cars tend to have either disc brakes on all four wheels or disc brakes in the front and drum brakes in the back.

How much should brake job cost? ›

A complete brake repair — one that includes pads, rotor and caliper replacement — typically averages between $300 and $800. However, depending on the make and model of your vehicle, you can easily spend more than $1,000 on a complete brake job.

Does a car use brakes when parked? ›

The parking brake will press against your rear brakes with less force than the primary braking system. Many people use the parking brake to keep their car in place when parked, especially on hills or steep inclines.

Do you drive first or parking brake? ›

Engaging the emergency brake first is easier on the transmission. When you're ready to leave, start your engine, press your primary brake, release the emergency brake and shift into drive. Remember that driving with your emergency brake on can damage your car.


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