The pistons squeeze out the brake fluid located there. The resulting pressure in the brake system is transmitted through the pipes to the wheel cylinders.
In them, pistons press the brake pads against the brake discs.
On the rear wheels of front-wheel drive Audi-100 cars manufactured before December 1992 with a 4-cylinder engine, the brake shoes are pressed against the brake drum. Other versions are equipped with disc mechanisms at the rear. Disc brakes were also installed before 12/92 in cars with 4-cylinder engines, if the car was equipped with ABS brakes.
Liquid pressure is supplied to two independent pipeline systems (brake drive circuits), namely for one front wheel and the rear wheel located opposite it (diagonal split braking system with dual circuit drive). If one brake circuit fails, one front wheel and the rear wheel on the other side of the vehicle may still be braked.
The parking brake acts on the rear wheels via a cable drive, regardless of whether drum or disc brakes are installed there.
In all-wheel drive models, as well as in front-wheel drive vehicles with 5- and 6-cylinder engines, ABS was installed already at the start of serial production (Anti Blocking System). In cars with a 4-cylinder engine, it was installed only as an option until 12/92. You will learn more about ABS in the next chapter.
Note: If one brake circuit fails, you will need to press the pedal much harder (the pedal stroke increases) for braking. The braking distance also becomes longer.