How car disc brakes work

30 October 2018 / Lindleys Autocentres

In 1917, a mechanic invented a new type of braking system that was hydraulically operated. A couple of years later, he improved his design and the first modern hydraulic braking system was introduced. Though unreliable due to problems with the manufacturing process it was adopted in the automotive industry with changes.

The man was called Malcolm Loughhead and would go onto become one of the founders of  Lockheed Corporation.

Today, due to advances in materials and improved manufacturing, disc brakes are much more effective and reliable.

We’ll begin the explanation for how disc brakes work with the main components. These are the brake pads, callipers, disc brakes and the hydraulic system.


It’s like riding a bike

The disc brakes are similar to the brakes on a bicycle. When pressure is applied on the lever, it pulls a metal string which squeezes the two callipers together causing friction between the rubber pads and the metal rim on the tyre.

Similarly, in a car when pressure is applied on the brake pedal this forces liquids through pistons and tubes to squeeze the brake pads together.

In a disc brake, the brake pads squeeze the rotor instead of the wheel, and the force is transmitted hydraulically instead of through a cable. Friction between the pads and the disc slows the car down and the disc gets very hot.

Most modern cars have disc brakes on the front wheels, and some high-performance cars have disc brakes on all four wheels.



The need for maintenance

As a result of the friction, the brake pads need maintenance or else problems such as squealing or grinding noises can become apparent (see How to Detect Issues With Your Brakes). Failure to fix the braking problems may result in a failed MOT.

The most common type of service required for brakes is changing the pads. Disc brake pads usually have a piece of metal on them called a wear indicator. When enough of the friction material is worn away, the wear indicator will contact the disc and make a squealing sound. This means it is time for new brake pads.

Checking the amount of wear on your brake pads will require some mechanical tools and time as well ensuring the wheel bolt tightness is correct to avoid overtightening. For some motorists, this can be time-consuming. If would like to save your time to check the amount of wear on your brakes pads Lindley’s offers a free brake checking service as well checking for other common brake problems.


Frequently asked questions about disc brakes


Q. Do brakes work when the engine is off?

Due to brakes being mechanically or hydraulically operated it means that the breaks can be operated when the car is off.

However, on some new cars due to handbrake being electrically operated rather than mechanically means that they may not work when the engine is off (no power to electrically operated brakes). However, they may still work if the key is in the ignition.

Q. How many types of brakes are there?

On a car, there are two types of braking systems; a handbrake (also known as a parking brake) and

Q. Why are there holes in disc brakes?

Manufacturers intentionally put holes into disc brakes to allow air to perforate the disc. This allows the disc to remain cooler when the callipers make contact with the disc. If the disc had no holes, the disc would reach high temperatures (as high as 500 ?) which would wear out the disc callipers and reduce the stopping ability.

Q. What are disc brakes made of?

Due to the high temperatures that disc brakes can reach they are often made out of cast iron due to the materials ability to handle high temperatures, ease of manufacture and low cost.

With that said, some brakes disc are made out of carbon-based composites, ceramics and alloys but tend to be more expensive.



Booking Summary
Selected location

No location selected.

Selected vehicle

No vehicle selected.

Selected date and time

Please select a date and time.

There are no items in your basket.