How Do Car Braking Systems Work?

The braking system is a critical component of any vehicle. It plays a critical role in ensuring driver and passenger safety.

A brake system is made up of several components that work together to stop the vehicle when the brake pedal is pressed. That is why it requires proper maintenance. However, many drivers are unaware of the importance of brake oil in preserving the system’s optimal performance.

Let’s learn more about the different types of braking systems, as well as the various brake oil types.

What is a Brake system?

A braking system plays a critical role in ensuring the safety of the vehicle and its occupants. It allows the driver to control the vehicle’s speed and bring it to a safe stop when required, preventing accidents and collisions.

The braking system is designed to convert the vehicle’s kinetic energy into thermal energy. It contains several parts, including brake pads, brake rotors, calipers, and brake fluid.

When the driver hits the brakes, the brake pads apply pressure to the brake rotors, causing friction that slows down the vehicle’s wheels. The calipers house the brake pads and exert the necessary pressure to stop the vehicle. The brake fluid transfers the force of the driver’s foot on the brake pedal to the calipers.

Disc and drum brakes are based on a hydraulic pressure system. Braking starts with a mechanical force — your foot pressing the brake pedal. The end result is that your vehicle safely stops. Below is a quick explanation of the five points of the system.

  • A piston compresses brake fluid inside the master cylinder located under your vehicle’s hood near your engine. This creates hydraulic pressure, generating a much bigger force than that of the small effort of pressing down on the pedal. See above image.
  • The pressure is transferred via the brake fluid through the brake lines and/or brake hoses (flexible tubes) that connect the lines with brake assemblies at each wheel.
  • There, wheel cylinders convert that hydraulic pressure back to mechanical force. Brake friction material is pushed against the brake disc or drum, slowing or stopping your vehicle.
  • The disc brake assembly is designed to safely stop your car when activated. More details about how this works below.
  • The drum brake assembly, equipped on some vehicles, is also designed to stop your vehicle when other points on the system are activated.

Parts of Braking system

The following are parts of the braking system:

  • Brake Pedal
  • Master Cylinder
  • Brake Pads
  • ABS Control Module
  • Brake Booster
  • Disc Brakes
  • Drum Brakes
  • Emergency Brake
  • Brake Pedal
  • Wheel Speed Sensors
Braking system

1. Brake Pedal

The pedal is what you push with your foot to activate the brakes. It causes brake fluid to flow through the system to put pressure on the brake pads.

The driver steps on the brake pedal to activate the brakes. A piston in the master cylinder moves when the pedal is pressed.

2. Master Cylinder

The master cylinder is basically a plunger that is activated by the brake pedal. It is what holds the brake fluid and forces it through the brake lines when activated.

Converts non-hydraulic pressure into hydraulic pressure that the wheel cylinders use to press the brake pads against the rotors to bring the vehicle to a stop.

3. Brake Lines

Generally made of steel, brake lines are what carry the brake fluid from the master cylinder reservoir to the wheels where pressure is applied to stop the car.

4. Wheel Cylinders

The brake pads are connected to the wheel cylinders which either squeeze (disc brakes) or push apart (drum brakes) the brake pads when fluid flows into them.

5. Brake Pads

The brake pads are what actually rub against the drums or rotors. They are made of composite materials and designed to last for many, many thousands of miles. However, if you ever hear a grinding or howling noise when you try to stop your car it likely means it is time for new brake pads.

Related: What are the Types of Brake Pads?

6. ABS Control Module

Found on vehicles with ABS brakes, the module performs diagnostic checks of the ABS braking system and determines when to send the correct pressure to each wheel to prevent the wheels from locking up.

7. Brake Booster

Reduces the amount of pressure needed for braking to allow any driver to operate the brakes. Uses engine vacuum and pressure to increase the force the brake pedal puts on the master cylinder.

8. Disc Brakes

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.

9. Drum Brakes

Located on the rear of the vehicle, drum brakes feature wheel cylinders, brake shoes, and a brake drum. When the brake pedal is pressed, the brake shoes are forced into the brake drum by the wheel cylinders, bringing the vehicle to a stop.

10. Emergency Brake

Operates independently of the main brake system to keep the vehicle from rolling away. Also known as a parking brake, hand brake, and e-brake, the emergency brake is mainly used to keep the vehicle in place when parked.

11. Wheel Speed Sensors

As part of the ABS brake system, speed sensors monitor the speed of each tire and send the info to the ABS control module.

Types of Brake Systems

The following are the types of braking systems:

  • Hydraulic braking system
  • Electromagnetic braking system
  • Servo braking system
  • Mechanical braking system

1. Hydraulic braking system

A hydraulic brake circuit has fluid-filled master and slave cylinders connected by pipes.

When you push the brake pedal it depresses a piston in the master cylinder, forcing fluid along the pipe. The fluid travels to slave cylinders at each wheel and fills them, forcing pistons out to apply the brakes.

Fluid pressure distributes itself evenly around the system. The combined surface ‘pushing’ area of all the slave pistons is much greater than that of the piston in the master cylinder. Consequently, the master piston has to travel several inches to move the slave pistons the fraction of an inch it takes to apply the brakes.

This arrangement allows great force to be exerted by the brakes, in the same way that a long-handled lever can easily lift a heavy object a short distance. Most modern cars are fitted with twin hydraulic circuits, with two master cylinders in tandem, in case one should fail.

Sometimes one circuit works the front brakes and one the rear brakes; or each circuit works both front brakes and one of the rear brakes; or one circuit works all four brakes and the other the front ones only.

Under heavy braking, so much weight may come off the rear wheels that they lock, possibly causing a dangerous skid.

For this reason, the rear brakes are deliberately made less powerful than the front.

Most cars now also have a load-sensitive pressure-limiting valve. It closes when heavy braking raises hydraulic pressure to a level that might cause the rear brakes to lock, and prevents any further movement of fluid to them.

Advanced cars may even have complex anti-lock systems that sense in various ways how the car is decelerating and whether any wheels are locking. Such systems apply and release the brakes in rapid succession to stop them from locking.

2. Electromagnetic braking system

Electromagnetic brakes or EM brakes are used to slow or stop vehicles using electromagnetic force to apply mechanical resistance (friction). They were originally called electro-mechanical brakes but over the years the name changed to “electromagnetic brakes”, referring to their actuation method which is generally unrelated to modern electro-mechanical brakes.

Since becoming popular in the mid-20th century, especially in trains and trams, the variety of applications and brake designs has increased dramatically, but the basic operation remains the same.

Both electromagnetic brakes and eddy current brakes use electromagnetic force, but electromagnetic brakes ultimately depend on friction whereas eddy current brakes use magnetic force directly.

Advantages of Electromagnetic braking system:

  • Electromagnetic braking is quick and cheap.
  • With electromagnetic braking, there are no maintenance costs such as regularly replacing the brake shoes.
  • Electromagnetic braking can improve the capacity of the system (such as higher speeds, heavy loads).
  • Some of the energy is delivered to the utility, which reduces running costs.
  • Electromagnetic braking generates a negligible amount of heat, while mechanical braking generates enormous heat on the brake shoes, which leads to brake failure.

3. Servo braking system

Also known as vacuum or vacuum-assisted braking. This system increases the pressure exerted on the pedal by the driver.

They use the vacuum that is produced in petrol engines by the air intake system in the intake pipe of the engine or by a vacuum pump in diesel engines.

A brake that uses power assistance to reduce human effort. An engine vacuum is often used in an automobile to flex a large diaphragm and operate the control cylinder.

  • Servo braking system boosters are used with the hydraulic braking system. The size of the cylinder and the wheels are practically used. Vacuum boosters increase the braking force.
  • Pressing the brake pedal releases the vacuum on the side of the booster. The difference in the air pressure pushes the diaphragm for braking the wheel.

4. Mechanical braking system

The mechanical braking system drives the handbrake or the emergency brake. This is the type of braking system where the braking force applied to the brake pedal is transmitted through the various mechanical connections such as cylindrical rods, fulcrums, springs, etc. to the final brake drum or disc rotor to stop the vehicle.

Mechanical brakes were used in several automobile motor vehicles, but are archaic these days due to their less effectiveness.

How Do You Maintain a Braking System?

Here are five keys to brake maintenance that will help you stay safe on the roads:

#1 Check Brake Pads and Rotors

The brake pads and rotors are the point of contact between your braking system and your tires. These elements deteriorate more easily than other components and require more frequent maintenance.

Friction between the tires and the brake pads cause heat, and this heat wears down the brake pad. It is important to inspect the quality and depth of the pads to make sure there is sufficient resistance.

If you notice you need to depress your brake pedal further or smell a burning odor, or the distance it takes to stop increases drastically, it may be time to check and replace your brake pads and rotors.

To check your brake pads and rotors at home, you need only remove the tire to assess the wear. If you notice wear or damage, replace them immediately, or take them to an auto shop for a disc brake repair service.

#2 Flush Your Brake Fluid

When you depress your brake pedal, pressure builds and is transferred through the brake fluid from the master cylinder, through the brake lines, and into the calipers, which transfer this pressure to the brake pads and rotors. Brake fluid is, therefore, extremely important because it is the messenger between you and your car’s braking system.

Unfortunately, brake fluid attracts moisture, which can be highly damaging to your braking system. Moisture in the brake fluid causes corrosion of the metal components of the brakes and reduces the boiling point of the fluid and affects the effectiveness of the brakes.

Brake fluid should be checked and changed every 25,000 miles. A cloudy or milky quality indicates the fluid must be changed.

#3 Bleed the Brake Lines

In addition to flushing the brake lines to change the brake fluid, it is also a good idea to bleed the brake line to remove excess air. When small amounts of air become trapped inside the brake line, it can reduce the efficacy of the braking system.

Bleeding the system removes the air from the brake line by depressing the brake pedal while adjusting the bleeder valve, and this should be done every 2– 3 years. This can be completed during a scheduled brake inspection service.

#4 Replace or Upgrade Brake Parts

Sometimes it may be necessary to replace some elements in your braking system, and this can be a good opportunity to upgrade to higher performance or specialized components. Parts such as slotted disc brakes which are more heat resistant or switching to ceramic pads, which are quieter and produce less brake dust, are popular upgrades.

Upgrading and replacing brake parts when necessary will improve the longevity and performance of your vehicle’s braking system.

#5 Braking System Care

One of the most effective ways to ensure the performance of your brakes is to look after them. There are many external factors that contribute to brake deterioration, such as:

  • Carrying too much weight
  • Unnecessary, late, or heavy braking
  • Wet weather

Avoiding these, and other situations that can affect your braking performance where possible, will keep your brakes performing better for longer and reduce the likelihood of brake failure related incidents.