Namely the brake booster. The brake booster ... enters via a valve on the side facing the brake pedal. A one-way check valve prevents this atmospheric pressure from entering the vacuum-only ...

According to NHTSA, "Incorrect material composition of the brake booster check valve may cause the check ... there may not be enough power assist to effectively operate the brakes (particularly ...

In power brake systems, which are found on virtually all vehicles, the brake booster is a component that multiplies the force the driver applies to the brake pedal. If the booster fails ...