Albert Dewandre (Liege, Belgium), an engineer and business owner, was the inventor of servo-brake or brake booster system “Dewandre” in 1927. It is a brake boosting system that uses the depression caused by the suction in the intake manifold of an internal combustion engine to reduce the pressure on the brake pedal. The advantage of the Deandre system is twofold: a softer push on the brake pedal, but also a notably shorter braking distance. His invention was manufactured and sold through the Robert Bosch company.
A brake booster is an enhanced master cylinder setup used to reduce the amount of pedal pressure needed for braking. It employs a booster set up to act with the master cylinder to give higher hydraulic pressure to the brakes and/or lower force applied on the brake pedal through a brake booster push-rod. The brake booster usually uses vacuum from the engine intake to boost the force applied by the pedal onto the master cylinder or may employ an extra vacuum pump to enable it. Without the engine running the brake pedal feels very hard and ineffective on the braking capability. An "active" booster is a non "conventional" booster where a solenoid is used to open the booster air valve to automatically push the master cylinder forward to perform some forms of dynamic stability control. Brake boosters come in either a single diaphragm or tandem diaphragm (which is generally used for bigger vehicles and trucks). They can be "cabin-breathers" (taking clean filtered air from inside the cabin thus may be noisier) or "engine-breathers" (less noisy but more at risk for becoming clogged with mud/ice if not protected properly).
Apart from this additional booster setup, the braking system is a normal hydraulic brake system.