The pistons displace the brake fluid in the cylinder. The resulting hydraulic pressure is distributed in the brake system through pipes and hoses to the wheel cylinders.
In the cylinders, the pistons press the brake pads against the brake disc or, on the rear wheels of models with less powerful engines, the brake shoes.
Fluid pressure is transmitted to the brake cylinders via two independent pipelines (brake circuits), namely to the front wheel and the opposite rear wheel (diagonally distributed dual-circuit brakes).
If one circuit fails, the front wheel and the rear wheel on the other sides remain operational. With the front wheel unbraked, you can turn, and the rear wheel unbraked keeps the rear of the car in the wheel
Manual (parking) the brake acts through cables on the rear wheels, regardless of whether drum or disc brakes are installed.
Some Audi models are equipped with Bosch anti-lock braking system (ABS).
Caution: If one of the brake circuits fails, it is necessary to press the brake pedal with greater force (with a longer pedal stroke), to obtain the same braking efficiency.