Brake booster (Opel Vectra B)

Disc brakes, unlike drum brakes, do not work with a self-amplifying effect: they require significantly more pedal force. Therefore, the Vectra has a pneumatic brake booster, which creates about 60% of the braking force.

This auxiliary device is located on the left in the engine compartment behind the main brake cylinder. But the brake pedal is directly connected to the brake piston of the main brake cylinder, so it is possible to brake even if the auxiliary device fails. But in this case, the required pedal pressure must be increased many times!

The auxiliary force is provided by the reduced pressure in the intake manifold. The brake booster is connected to the intake manifold by a hose. When braking, the difference between atmospheric pressure and the reduced pressure in the intake manifold displaces a large elastic membrane and additionally presses on the pistons in the master brake cylinder.

If the engine is not running, the brake booster cannot develop power either (additional) braking force. Therefore, you should press harder on the pedal if, for example, your car is being towed. If the engine suddenly stops on the road, you still have some reserve for a few short brakings - only then should the calf muscles work at full strength.