The brake system in your vehicle allows the driver to slow down or stop in a consistent and reliable manner. The brakes on your car work by converting the kinetic energy of movement into thermal energy (heat).
Each time you step on the brake pedal, the speed of the spinning wheels underneath your vehicle is reduced proportionately to how much pressure you apply to the pedal. A vehicle will have either a disc brakes or drum brakes to create the necessary friction for this to take place.
Modern car brake systems are referred to as power brake systems. These systems use a brake booster that amplifies the force you apply to the brake pedal. This makes braking so much easier for drivers. Power braking allows you to apply just a little bit of pressure to the brake pedal in order for the vehicle to slow down.
In the classic mechanical brake system, there was a cable which connected the brake pedal and brake shoe assembly together. When the driver stepped on the brake pedal, it pulled on the cable and allowed the brake drum spinning to slow down. This was used on cars in the early 20th century, and is still used on bikes today.
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Car Brake System Components
Below is a list of the main parts of a car brake system. We have included both the components of the disc and drum brake systems. Most modern vehicles have disc brakes on all four corners, but some economy cars still use drum brakes in the rear.
1) Brake Pedal
The brake pedal is one of the most important components of your car’s braking system. Located next to the gas pedal, it’s the pedal you step on to slow down or stop your vehicle. But did you know that the brake pedal is connected to the entire braking system on the inside?
When you press down on the brake pedal, it activates the master cylinder, which in turn sends hydraulic fluid to the brake calipers or wheel cylinders. This creates friction between the brake pads and rotors, or brake shoes and drums, which slows down your vehicle.
2) Brake Booster
The brake booster (also called a vacuum servo) is part of the power braking system and it uses either engine vacuum or a vacuum pump to amplify the foot pressure you place on the brake pedal.
This means that you don’t have to apply as much pressure to the pedal to slow down your vehicle. It’s like having a helping hand to make braking easier and more efficient.
The brake booster is a game-changer for modern cars, making it easier for drivers to brake smoothly and quickly in any situation.
Read Also:
- 4 Symptoms of a Bad Brake Booster and Replacement Cost
- Brake Booster Check Valve Function and Bad Symptoms
3) Master Cylinder
The brake master cylinder pushes hydraulic fluid down into the brake lines from the brake fluid reservoir.
Most master cylinders are actually split into two or more individual cylinders for safety reasons. Typically each cylinder manages the braking ability of one front wheel and the opposite rear wheel. That way, if one cylinder fails, the other cylinder can still slow down the car and allow the driver to maintain a reasonable amount of control.
Some vehicles will use one cylinder per axle (front/rear split). Others use multiple cylinders per wheel for maximum redundancy in case of a failure.
The master cylinder works by managing the amount of hydraulic pressure that is placed on the hydraulic fluids. More pressure will slow down the vehicle more quickly.
4) Brake Fluid Reservoir
The brake fluid reservoir is a plastic container typically located on top of or near the master cylinder. Its main function is to store brake fluid and supply it to the master cylinder as needed. Here are some additional points about the brake fluid reservoir:
- It allows for easy visual inspection of brake fluid levels.
- The reservoir has “MIN” and “MAX” markings to indicate proper fluid levels.
- It compensates for fluid level changes due to brake pad wear over time.
- The reservoir cap often includes a warning sensor to alert drivers of low fluid levels.
- It’s designed with a small vent to maintain atmospheric pressure inside the reservoir.
5) Brake Lines
Brake lines transfer brake fluid between the master cylinder and wheels. This is the hydraulic fluid that allows braking to be so easy.
Unlike air, hydraulic fluid is not compressible. That means when you push on the brake pedal, that force is directly transferred to the piston in the brake caliper, or shoe in the brake drum.
A brake fluid leak is potentially dangerous as it may introduce air in the system. When there is no brake fluid, the brakes will not work effectively.
6) Disc Brake Components
Disc brakes are the most common type in modern vehicles, especially for front wheels. The main components are:
- Brake Rotor – Each wheel has a brake rotor that spins with the vehicle’s motion. The rotor is typically made of cast iron, which can absorb significant heat. Many rotors are vented, featuring openings between two discs to direct airflow and cool the rotor as it rotates. Rear brakes often use solid rotors since they do less work in stopping the vehicle.
- Brake Pad – Brake pads create friction as they rub against the spinning brake disc. They’re made of different materials that affect their longevity and optimum heat range. Operating a brake pad outside its optimum heat range may increase stopping distance.
- Brake Caliper – Brake calipers provide the clamping force that pushes the brake pad into the brake rotor using hydraulic pressure. When you step on the brake, hydraulic pressure from the master cylinder pushes brake fluid into one or more pistons housed in the brake caliper. These pistons then push on the brake pads with great force.
See Also: What Causes Brake Calipers to Stick?
7) Drum Brake Components
While less common in modern vehicles, drum brakes are still found on some rear wheels, especially in economy cars. The main components are:
- Brake Drum – The brake drum rotates with the wheel. When brakes are applied, the brake shoe is pushed against the inside of the drum, creating friction to stop the car. This simple but effective system has been used for decades.
- Brake Shoe – Unlike flat brake pads, brake shoes are curved to fit inside the brake drum. As the drum rotates, the brake shoe is pushed against it to create the necessary friction to stop the vehicle.
8) Parking/Emergency Brake
The parking brake, also known as the emergency brake or hand brake, is a secondary braking system that operates independently of the main hydraulic brakes. Its primary functions are:
- To keep the vehicle stationary when parked, especially on inclines.
- To serve as a backup braking system in case of main brake system failure.
There are two main types of emergency brake systems in modern vehicles: manual and electronic. Each has their benefits but neither are immune from problems.
Manual Parking Brake Components and Operation:
- Lever or pedal – Usually located between the front seats or as a pedal in the driver’s footwell.
- Cables – When engaged, the lever or pedal pulls on cables.
- Linkage – The cables connect to linkages at the rear wheels.
- Brake mechanism – Depending on the vehicle, it may engage the rear disc brake calipers, separate drum brake shoes inside the rear brake rotors, or the existing rear drum brakes.
When activated, the manual emergency brake applies force to the rear wheels only, which is usually sufficient to hold the vehicle in place.
Electronic Parking Brake (EPB):
Most modern vehicles now use electronic parking brakes. These systems use electric motors instead of cables to engage the rear brakes. Features include:
- Button activation – Typically, a switch or button in the cabin replaces the traditional lever or pedal.
- Automatic engagement – Many EPB systems automatically engage when the vehicle is put in park or turned off.
- Dynamic braking – Some systems can provide emergency braking if activated while the vehicle is in motion.
- Integration with other systems – EPB often works with hill-start assist and other electronic stability features.
Both manual and electronic systems typically engage only the rear brakes, which is usually sufficient to hold the vehicle in place when parked.
9) Anti-lock Braking System (ABS) Components
The ABS is a safety feature that prevents wheel lockup during hard braking. Its main components are:
- Wheel Speed Sensors – These sensors detect how fast each wheel is spinning. If wheels lock up due to hard braking, one or more wheels will spin at different speeds. This speed difference is used by the ABS module to determine how to apply individual brakes.
- ABS Module – The ABS module is a computer for the braking system. It modulates the brakes when one or more tires are at the limit of traction. Using input from wheel speed sensors and possibly other sensors, it releases brake pressure to specific wheels that start to lock up, allowing them to regain traction. This gives drivers the ability to stop as quickly as possible, even when applying maximum brake pressure.
The ABS system allows for controlled, safe stops by preventing wheel lockup, which maintains steering control and reduces stopping distances on most surfaces.
See Also: 6 Reasons Your ABS Light Is On
While not exactly a component of a car’s brake system, brake fluid is just as important as any other part. Brake fluid is a type of hydraulic fluid that transfers pressure from the master cylinder down to the brake components on each wheel.
It’s important to know that brake fluid is hygroscopic, which means it can attract water. This is a bit of a problem because water can cause corrosion and damage rubber seals. Because of that, you’ll want to make sure that you periodically check the brake fluid level (and condition) in the reservoir to keep everything running as it should.
Speaking of the brake fluid reservoir, this little container sits on top of the master cylinder and supplies it with fluid. Whenever you press the brake pedal, the master cylinder forces fluid out of the reservoir along the brake pipes to the slave cylinders at the wheels.
Materials Used in Brake Systems
Let’s talk about the materials that are commonly used in brake systems.
First of all, rubber is vital in creating the brake hoses and seals within your braking system. You know those flexible brake lines that connect the master cylinder to the brake calipers and wheel cylinders? That’s where rubber comes in.
This material allows the lines to flex when your car’s suspension moves. In addition, the rubber seals within the system help maintain pressure and prevent fluid leaks.
Cast iron is the go-to material for brake rotors and drums found in most cars. It’s popular because it delivers excellent heat dissipation and has enough strength to tolerate the friction and heat produced during braking. And here’s a bonus: cast iron is relatively cheap, making it an affordable option for both manufacturers and car owners.
Other materials used in braking systems:
- Aluminum – Found in some high-performance brake calipers, aluminum is lightweight and corrosion-resistant.
- Steel – Often used for constructing ABS modules, brake boosters, and various components that require strength and durability. Braided stainless steel brake lines are often used in high performance vehicles over rubber.
- Ceramics – These are used in some premium or high-performance brake pads, offering better heat management and reduced brake dust.
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Hello, can you explain me what is a “travelling brake switch” and “land and water status” in automobiles, please?
hi i bought 2009 accura tsx brakes are very soft i have to push all the way to stop vahicle we try every thing change cylender brake fluid nothing work now when we bring it to dealer they said they can change abs for 5000 $ they said thats the only thing left
Maybe the ABS system just needs to be bled.
I would just buy a new car. But you can check the rotors, sometimes they were too and most times we forget to look at them good enough to really see them. But if those are worn you’ll need to change your brakes more often than if not. And stopping is much slower.
Jim,
I’m rebuilding a 1956 Ford Fairlane Crown Victoria. The customer requested power disc brakes on the front and drum brakes on the rear. Could you recommend a brake line schematic. The master cylinder that came with the kit is a universal and has 4 ports. Its a dual chamber. The booster is also a GM universal and I’m making an adapter for the firewall to make it work. The original master cylinder was a single chamber. I purchased an adjustable equalizer valve that Speedway recommended but I’m not sure where to install.
Thank you for you discribition i’m cedric form rwanda i’m mechanicie i like to perform those lesson. merry chrismas my freind
Glad you enjoyed the article, Cedric. Merry Christmas to you too!
Very explination
I’m driving a Kia pregio mini bus.when I stepped on the brakes, one side locked. What is the problem?
Hard to say without someone seeing it in person. Could be a stuck caliper, bad brake hose, bad master cylinder, bad proportioning valve, or something else entirely. I’d have it looked at by a professional.
I am driving a 25 str coaster bus, the steering shakes when I step on the brakes. Can the stabiliser bushings be the cause or is it the faulty brake system.
It’s possible the rotors are just warped. I’d have the brake system inspected.
The brake discs have the problem sir.Do disc skimming or put on new ones.
The information is very useful, thanks so much