A power brake booster, or hydraulic brake system, uses a hydraulic system while a vacuum brake booster uses a vacuum to stop your vehicle.
If you own a vehicle manufactured after 1968, it is likely that you have an electric brake system. Although there are several evolutions of this essential vehicle operating system, the basic principle of applying leverage, hydraulic force, and friction remains the fundamental process for slowing and stopping a vehicle. One of the most misunderstood issues is understanding the difference between a power brake booster and a vacuum brake booster.
In truth, a power brake booster and a vacuum brake booster are the same part. Each uses vacuum pressure to assist in the application of hydraulic fluid and by using the friction between the brake rotor and the pads. Where confusion exists, a hydraulic brake assist system called Hydro-Boost is referred to as a power brake booster. A Hydro-Boost system bypasses the need for vacuum and uses direct hydraulic pressure to accomplish the same task.
To simplify things, let’s break down how a vacuum brake booster works as opposed to a hydraulic-based brake booster, as well as some tests to diagnose potential problems with both.
How does the vacuum brake booster work?
A vacuum-based brake booster gets its power via a vacuum system attached to the engine’s intake manifold. The vacuum flows into the brake booster, which applies pressure to the hydraulic brake lines when the brake pedal is pressed. This system is used in a vacuum servo or a brake booster. The vacuum provided by the engine activates an internal bladder, which supplies force to the hydraulic brake lines.
There are generally three sources of failure for a vacuum brake booster:
No vacuum pressure from the engine.
Inability of the brake booster to absorb or create a vacuum inside.
Broken internal parts, such as the check valve and vacuum hose, inside the brake booster that fail to power the hydraulic lines.
What is a Hydro-Boost Power Assist Service?
The hydro-boost power system works almost identically to the vacuum system, but instead of relying on vacuum pressure, it uses direct hydraulic pressure. It is powered by the power steering pump and usually fails at the same time as the power steering. In fact, it is usually the first indicator of a hydraulic brake failure. However, this system uses a series of backups to keep the power brakes running for a short period in case of a power steering hose rupture or a broken power steering belt.
Why is a brake booster called a vacuum brake booster?
A brake booster is designed to provide added power assistance to help apply the brakes. It is primarily due to the work of a brake booster that a vacuum-assisted system is called a brake booster. It is also common for a hydraulic brake booster to also be associated with the term brake booster. The key to knowing which type of brake booster is used on your vehicle is to consult your vehicle’s owner’s manual.
Most of the time, this question is asked when a problem with your braking system has arisen. A professional mechanic can be very helpful in diagnosing a problem with your braking system. During a brake system inspection, they will perform several diagnostic checks to determine the root source. This includes the brake booster. Whether you have a vacuum or hydraulic system, they will be able to identify the issue and recommend the best replacement parts and necessary repairs to get your car back on the road.