Outback F4-2.5L (2008)
Hydraulic Brake Booster: Description and Operation
Brake Booster
The brake booster is a tandem type that uses two diaphragms.
By utilizing the differential pressure between the intake manifold vacuum and atmospheric pressure, a high braking force can be obtained even when the
pedal depressing effort is small.
The brake booster is installed between the brake pedal and master cylinder. This contributes to improve the response to the brake pedal. If it fails, the
brake servo effect is lost requiring a larger pedal effort, however, the braking force is still maintained.
