Power Brake Booster

What Is A Power Brake Booster?

Power brake boosters, also called brake servos, are designed to lessen the force needed to depress your brake pedal for easier, more responsive stops. The power brake booster is part of your power brake system and typically uses vacuum from the engine to boost the force that is applied to the master cylinder - requiring less effort from the driver when braking. Before power brakes were introduced, manual braking required more force to begin slowing the vehicle. Power brake systems and the power brake booster were designed to provide better, safer stops, and are equipped on all modern vehicles. There are two types of power brake boosters: vacuum power brake boosters and hydro-boost or hydraulic brake boosters. Vacuum brake boosters use the vacuum power generated by the engine. A controlled vacuum chamber on the inside of the booster with a constant vacuum reservoir on the front helps vacuum brake boosters provide constant negative pressure to the brake pedal while the vehicle is running - resulting in a brake pedal that is easier to press down. Hydraulic brake boosters use hydraulic fluid pressure from the power steering pump to exert more force on the brake fluid within the master cylinder. Hydraulic brake boosters feature a two-chambered, belt-driven pump, and are much more common on diesel vehicles which do not produce vacuum while running. Power brake boosters are made to last a vehicle's lifespan, and are not a typical wear part, but can suffer mechanical failure and damage that can prevent them from working their best. Signs of a bad brake booster include longer stopping time, engine stalling while braking, or a brake pedal that is soft, spongy, or unusually easy or hard to depress. It's important to remember that a damaged or leaking master cylinder can damage internal components, including the vacuum diaphragm, with brake fluid. Brake fluid entering the power brake booster will eventually degrade the rubber membrane and cause it to fail to hold vacuum. This may result in whooshing noises or the sound of leaking air when you depress the brake pedal, and vacuum leaks from the brake booster can also cause the engine to idle or run rough, misfire, or experience a lean fuel mixture. If you suspect your power brake booster has failed, inspect your booster and other brake system parts for signs of leaks, cracks, or obvious component damage, and check brake fluid levels, brake lines and hoses, and the vacuum system itself. Understanding braking systems can not only keep you safer on the road but can also help you identify brake system issues easier so you can make your repairs and keep driving safely. Shop O'Reilly Auto Parts for replacement power brake boosters, master cylinders, brake fluid, and more brake system parts to perform a complete and confident brake system repair.