Brake Boosters|brake boosters

What’s luxury without comfort and innovation without utility? A component invented to provide maximum utility and ease of driving, brake boosters are now a crucial component for every car. Often dubbed as power brakes, they have changed how people drive. Here’s everything you need to know about Brake Boosters.

What is a brake booster in a car?

Before you get to understand how a brake booster works and why it is needed, it’s essential to know what a brake booster is. In simple terms, a brake booster, also known as a vacuum booster, is a safety component for brakes that amplifies the force exerted on the brake pedal and transfers that boosted power to the master cylinder of the brake.

Going into the details of it, brake boosters make use of the engine vacuum to multiply the braking force before sending it to the master cylinder. By doing so, a brake booster makes braking easier, more convenient and less tiring, especially in traffic scenarios.

Also Read: What Are The Signs Of A Bad Starter? How Do You Identify That Your Starter Is Failing?

How do brake boosters work?

In order to better understand how do brake boosters work, knowing how a typical braking system works is a must. A braking system at a very basic level works when you depress your car’s brake pedal, which via a connected lever depresses a piston into the component called the master cylinder that’s filled with hydraulic fluid. When this happens, hydraulic fluid is released into a system of pipes that magnify the force of the pedal. This force is then released on the disc/drum brakes, which through friction, causes the vehicle to slow down or halt. 

And now that you know about brakes, it’s time to know how a brake booster comes into the equation. The brake booster is located in the middle of the brake pedal and the master cylinder in order to multiply the force exerted by the brake pedal. A brake or vacuum booster does this by utilising the power of the engine’s vacuum. This is done via a diaphragm system wherein a vacuum and a little bit of air are utilised to add force/power to the brake.

Whenever you depress your brake pedal, the lever that pushes a piston into the master cylinder cracks open a small valve in the brake booster that lets air enter one side of the diaphragm. This substantially increases the pressure and pushes the lever further along, which in turn pushes down the piston in the master cylinder, however, with a multiplied force.

car accessories image

Types of Brake Boosters

While every brake booster has a common goal of multiplying the brake force, there are three major types of brake boosters, depending on what type of car you drive. Nonetheless, every brake booster is typically located between the brake pedal and the master cylinder.

  1. Vacuum Brake Booster

The most widely and commonly used brake booster is the vacuum brake booster. This is a common finding onboard vehicles that run on naturally aspirated engines, as this type of booster utilises the engine vacuum in order to amplify the brake pressure.

  1.  Vacuum Pump

While in naturally aspirated petrol engines, the engine vacuum can be utilised, in other kinds of vehicles such as diesel, turbocharged, hybrid or electric cars, a vacuum pump booster is used.

These vacuum pumps can either be operated mechanically from the engine or through an electric motor (electric brake booster). Even in a naturally aspirated engine, a vacuum pump can still be used if the vehicle is used in high-altitude terrain, where it isn’t able to produce enough vacuum.

  1.  Hydraulic Brake Boosters

Another kind of brake booster, a hydraulic booster utilises hydraulic pressure that is directly generated by the power steering pump instead of relying on any kind of vacuum pressure be it from the engine manifold, or from any vacuum pump.

Also read Turbocharger vs Supercharger: Which is better?

Do you even need a brake booster?

Imagine the days when people used to turn the steering all the way back to its original position after every turn. Difficult to even imagine isn’t it? Well, a similar difficulty would have been faced had brake boosters wouldn’t be there. Much like power steering, a brake booster is also an invention that was built to make your driving experience comfortable by reducing the pressure on your legs, every time you brake. 

But that’s not all, brake boosters also make sure your braking system works efficiently and help you engage them more easily. They are crucial in situations where you need to brake before you think and need to get your vehicle at vehicle halted. Moreover, in countries like India, where traffic is a common sight, a continuous application of brakes is a must. In such scenarios, the absence of a brake booster will make you drive on alternative days, with leg-day fatigue in between!

Symptoms of a failing brake booster

One of the many crucial components onboard your vehicle, a brake booster plays an important part in everyday driving. But much like all other components, the brake booster is also prone to damage and fault. Here are 7 symptoms of a failing brake booster, so that you know when to take action. 

  1. Stiff Braking

Since brake boosters are designed to reduce braking pressure, if you ever notice your brake pedal becoming harder than usual, then there might be problems with your brake booster. Any failure in the brake booster reduces its ability to multiply brake force, which makes braking require more force than usual.

  1. A high braking distance

Braking is something that should give an immediate result. After all, your safety depends on it. However, if you notice that it’s taking longer for your vehicle to stop after braking, chances are your brake booster is suffering from some fault.

  1. Issues with the pedal position

While the ABC (Accelerator, Brake and Clutch) pedals in your car are positioned in a way that results in maximum utility, if you notice that the brake pedal is depressing less than usual, or taking more time to return to its original position, chances are that there is an imbalance in the vacuum chamber which is a big sign of a failing booster.

Also read Role of the clutch in your vehicle

  1. Noise while braking

Quite a common problem, if you ever notice a hissing noise every time you brake, there are chances that there is a leak in the vacuum hose resulting in the vacuum booster leaking through the housing. This could lead to a complete brake booster failure.

  1. Problems with engine function 

A serious issue to cater to, problems with engine function might also indicate a brake booster failure. Consider a situation where there is a leak in the diaphragm that leads to air being drawn into the engine system. If this happens the air can badly affect the fuel mix in the engine which can lead to severe kinds of problems such as increased engine temperature, reduced cooling-off action, pre-ignition hassles and a lot more.

  1. Warning Lights Displayed

In vehicles that have an electronic brake booster, any failure in the brake booster will affect the ABS system. This will result in an ABS, traction or stability control warning light being displayed on the MID. If this happens, make sure to get your brake booster tested.

Also read Anti Lock Braking System: What’s It And How Does It Work?

  1. Fluid Leak

A fluid leak is the biggest indicator of issues with your car. And while a fluid leak can indicate a host of problems, in vehicles that are fitted with hydraulic brake boosters, a leak can indicate power steering fluid that is a direct signal that your hydro-brake boost assembly will also fail.

How to test your brake boosters

While signs and symptoms of a failing brake booster are easy to catch, there are chances that you might end up ignoring them. This is why it’s important to know how to test your brake booster especially when your car has a vacuum booster installed. 

Since vacuum brake boosters are designed in such a way that they can hold enough vacuum to let you engage your brakes a few times without the engine running, this phenomenon can be used to even test if your brake boosters are up and running.

Here’s how you can do the brake booster test: 

  • With the engine turned off, press the brake pedal a few times.
  • After that, press the brake pedal lightly while also turning on the engine.
  • The brake pedal should become firm in a while.
  • However, if the brake pedal becomes stiff or there’s no change whatsoever, it is possible that there is an issue with the brake booster.


A crucial component that ensures not only a comfortable and convenient ride but also the safety of you and your loved ones, brake boosters have truly changed the way people drive. Without a brake booster, braking will never be the same. 


Q1. How do brake boosters work?
. A brake booster, also known as a vacuum booster, is a safety component for brakes that amplifies the force exerted on the brake pedal and transfers that boosted power to the master cylinder of the brake.

Q2. How to replace a brake booster?
. The brake booster is generally located between the brake pedal and the master cylinder and can be replaced by an experienced mechanical technician.

Q3. How long to replace the brake booster?
. Replacing the brake booster can take anywhere between 2 to 4 hours.

Q4. How long should the brake booster hold vacuum?
.Vacuum brake boosters are designed in such a way that they can hold enough vacuum to let you engage your brakes a few times without the engine running.

Q5. How many brake boosters does a car have?
. There is no simple formula to define how many boosters a car might have. Depending on various factors, however, typically a car has two brake boosters.

Similar Posts