Vacuum Brake Assist System Operation
WARNING: This page does not describe the selected car, but rather 12 other vehicles, including the 2003 GMC Yukon XL, 2003 GMC Yukon, 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, and 2003 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.
Brake system input force is multiplied by the brake pedal and transferred by the pedal pushrod to the hydraulic brake master cylinder. Effort required to apply the brake system is reduced by the vacuum brake booster.