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What Exactly Does Your Brake Booster Do?

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Before power steering became an essential feature in every car, people would be using excessive strain to turn corners and park their car. The introduction of power steering very much changed the game in the automotive industry. It made driving more effortless and enjoyable. Within a similar vein comes brake booster technology, known in the automotive industry as power brakes or brake assist. Power brakes are possible thanks to the brake booster. This addition to a car’s regular braking system helped drivers exert less force when braking so that they can enjoy the driving process a lot more (and tire out their legs less). So, let’s learn more about this cool (yet slightly less understood) technology and what it does for your ride.

What Exactly is a Brake Booster?

A brake booster, also known as a ‘brake servo’ or ‘vacuum booster’, does exactly as the name suggests, it helps to ‘boost’ the performance of the brakes. A brake booster makes it easier for the driver to brake by increasing the force exerted without the need for additional force applied on the foot pedal. This effect is achieved through the use of a vacuum system that amplifies the pressure of the brake pedal’s lever on the master cylinder, and therefore brakes (which will be explained below). It provides assistance to the overall braking system by ensuring the brake pads clamp correctly and with enough force. Today, there are various types of boosters, the most popular including the dual-piston master cylinder, vacuum boost brakes, dual-diaphragm vacuum boost brakes, hydro-boost brakes, and electric hydro-boost brakes. Which one of these your car contains depends on the size and year of your car; however, the most classic model is the standard vacuum booster.

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How Does it Work?

Firstly, before we get into booster technology, it’s good to understand how regular brakes work. This is a pretty simple system – you push down on a brake pedal which (through a connected lever) pushes a piston into the master cylinder filled with hydraulic fluid. The hydraulic fluid is squirted into a system of wider pipes to magnify the force of the pedal. This force is then exerted onto the disc brakes (or drum brakes depending on the age of the car), which consists of a disc rotor, a brake calliper, and a brake pad. The hydraulic fluid released when the brake pedal is depressed causes the brake calliper to push the brake pad against the disc rotors attached to a wheel. Overall, this causes friction and the car wheels to stop rotating. That’s it.

So, where does a brake booster come in?

The brake booster is located between the brake pedal and the master cylinder and functions to multiply the force of the brake pedal further. This is done by having the brake booster function utilise the power of the engine’s vacuum (in petrol-powered cars) to emphasise the force your foot uses on the master cylinder. The booster does this by using a diaphragm system whereby a vacuum (and a little air) is used to add force to the brakes. When you push the brake pedal down, the lever that passes through to the master cylinder cracks open a small valve in the booster that allows air to enter one side of the diaphragm. This increases the pressure on that side of the diaphragm and further pushes the lever along, which pushes the piston in the master cylinder – and the rest is business as usual. That’s essentially how it works!

Why Do You Need a Brake Booster?

Just like steering was no easy feat before power steering became the norm, neither was braking. Both of these inventions made the entire driving experience what it is today – and most people would say driving is pretty darn easy! In a world without brake boosters, you’d definitely need to give leg day a rest. But taking the pressure off your leg muscles isn’t the only advantage of brake boosters – they also are there for safety reasons. They ensure your brakes are working effectively and help you activate them more readily. They help in those situations where you have to brake before you have time to think, making your car come to a halt a lot faster and with less effort.

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Signs of a Bad Brake Booster

The installation of a booster does improve the safety of your car; however, like any part of a car, it can wear and diminish over time. Therefore, it is crucial to be aware of the signs and symptoms of a failing brake booster to ensure quick diagnosis and remedy. Here are the common signs that something’s not right with your brakes. Remember, you should not continue to drive with a failing brake booster system as your car can run at uncontrollable speeds and cause accidents.

  • The brake pedal is hard to press. This often happens over time as the vacuum diminishes. Make sure you go for a service as soon as you start noticing this issue as it can limit the braking ability of your car.
  • You notice the distance of braking is longer. This could be due to air bubbles in the vacuum that can enter through the master cylinder. Again, this diminished the braking capability of your booster.
  • You notice the brake pedal is higher than usual. This could mean that the vacuum has pushed it out. This could cause problems when you’re driving.
  • Stalling engine and hissing sound. This is when the vacuum starts to ‘leak’ or escape.


Final Stop

Brake booster technology is one of those technologies that don’t get enough credit. Everyone’s heard of power steering but not many know that our brakes get some assistance as well. These two features make driving as effortless and enjoyable as it is today. What could be easier than having to exert very little energy when driving? Oh, that’s right, not driving at all – hurry up autonomous cars (the obvious next stage in driving technology)!

Just as important as a functional set of brakes, a clear and chip-free windscreen helps us see the road and adds to our safety. If your windscreen is chipped, get it repaired with Novus before it turns into a crack. A repair with Novus is fast, efficient, and reliable. Call us today on 13 22 34.

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