Power Brake Boosters: How They Work and Why They Fail

August 2, 2021 4:33 pm Published by Leave your thoughts

In the same way your power steering makes it easier to turn the wheels of your car, power brake boosters make it easier for you to apply the brake pedal. Considering that stopping your two-ton vehicle is critical to its function, power brake boosters are crucial components to your car.

Fortunately, power brake boosters don’t fail very often, but understanding how they work and why they do occasionally fail could be helpful knowledge to have as a vehicle owner. Here’s how power brake boosters work, and why they might give out.

How power brake boosters work

A brake booster is an apparatus that reduces the amount of necessary force that needs to be applied to the brake pedal to stop the car. Put another way, it “boosts” the amount of force you use when pressing the brake pedal, making it easier to halt your vehicle.

Pushing the brake pedal essentially triggers a reaction in your vehicle that sets several mechanisms into motion. The most common brake booster is a vacuum brake booster. A vacuum brake booster is usually situated between the brake pedal and the master brake cylinder. It uses a vacuum system in concert with the intake manifold to achieve the desired effect. The vacuum booster consists of a flexible, movable container (sometimes called a diaphragm) split into two parts with an air valve in the middle.

The inside of the container is vacuum sealed, and when the brake pedal is applied, the brake pedal output rod triggers a chain reaction that lets a small amount of air into the container. This small amount of air creates an imbalance and sends the diaphragm toward the lower pressure side, and it in turn pulls the brake pedal output rod along with it, in effect amplifying the brake pedal’s force.

Why brake boosters fail

Because brake boosters use a vacuum seal and an air valve to function, any problems with those elements will affect its ability to do its job. If the air valve leaks or fails, it might allow fluid into the diaphragm, and that would significantly reduce its power output.

The issues that plague the vacuum seal usually stem from the breakdown of the vacuum hose connected to the diaphragm that helps create the vacuum. If this hose is clogged or has holes in it, it won’t be able to create the necessary vacuum seal. If the vacuum seal is compromised, the power of your brake booster will likely diminish. You may notice this when the brake pedal becomes harder to push down.

The good news about power brake boosters is that they’ll likely last for the life of the car. The bad news is that if you’re having issues with your power brake booster, you might need to have the master brake cylinder and the brake booster completely replaced.

Call for brake service today

Now that you know what power brake boosters are, how they work and why they might fail, give Rivergate Muffler & Auto Repair for assistance with yours. We have the knowledge and experience to handle a litany of car troubles, and we’d be happy to help you with anything you need.

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