When learning how to do something, it’s generally beneficial to have a basic understanding of how something works before learning how to use it. With that in mind, detailed below is a basic guide on how car brakes work along with a diagram to follow.

How Car Brakes Work

Following the ‘How Car Brakes Work’ diagram above, we’ll start off with number 1, the brake pedal.

1. Brake Pedal

In order to slow down a car, the driver applies pressure to the brake pedal. However, to get the brakes to work effectively, quite a large amount of force is needed when pressing the brake pedal. To help reduce the amount of force that the driver needs to push on the brake pedal, just after the brake pedal is something called a vacuum brake booster.

2. Vacuum Brake Booster

As the driver pushes the brake pedal, a push rod enters a metal box called a vacuum brake booster. This box is divided into two halves called chambers. The chambers are divided by a diaphragm that moves with the brake push rod.

The purpose of the vacuum brake booster is to increase the amount of force applied to the brakes so that the driver doesn’t have to push the pedal so hard and it does this by use or air pressure.

The left chamber is connected to the engine where the air is sucked out to create a negative air pressure, or a vacuum and the right chamber contains normal air pressure, which is positive. When the driver presses the brake pedal, the diaphragm is pulled over into the vacuum chamber. This difference in pressure makes it easier for the driver to apply the brakes.

3. Brake Master Cylinder

From the vacuum brake booster, the push rod then enters the brake master cylinder. The brake rod pushes a piston which forces pressurised brake fluid down the brake lines to the four brake calipers, one on each wheel. 

Brake fluid is an important part of your cars braking system. If your car’s brake fluid is very old or the level is very low inside the fluid reservoir, your brakes may not function to the best of their ability.

4. Brake Caliper

Inside the brake caliper, pressurised brake fluid pushes a piston that in turn pushes the brake pads against the brake disc rotors. The harder you push the brake pedal, the greater the force that the pads push against the rotors and the quicker the car slows down.

5. Brake Disc Rotor

Brake pads are made from friction materials that when pressed up against the rotating metal brake disc rotors creates friction that slows the vehicle down.

That’s the basics on how car brakes work. Knowing how your car’s brakes work and operate should help with operation and maintenance. Under normal driving conditions, your car’s brakes should be applied gently and increase pressure as you bring the vehicle to a stop.

For maintenance, brake pads will occasionally require replacement, less frequently the rotors require changing and brake fluid levels should be checked.