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Home >> Mercury >> 2009 >> Mariner Base, 2.5 7, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 39 (Brake Booster System - Power Brake Actuation) >> Description And Operation >> Brake Booster

Brake Booster

WARNING: This page is about a different car, the 2009 Ford Mustang. However, it is still accessible from the selected car via links, so may be relevant.

The power brake actuation system consists of the following components:

The brake booster uses engine vacuum from the intake manifold to create a partial vacuum inside the vacuum booster on both sides of the diaphragm. When the brake pedal is pressed, the booster rod opens a valve, allowing air to enter the booster on one side of the diaphragm while sealing off the opposite side. This increases pressure on that side of the diaphragm so that it helps push the rod, which in turn pushes the piston in the master cylinder. As the brake pedal is released, the valve seals off the outside air supply while opening the vacuum valve. This restores vacuum to both sides of the diaphragm, allowing everything to return to its original position.