General description of the various components of the braking system (Mercedes-Benz Sprinter 903)

Master brake cylinder. Converts mechanical force on the brake pedal into hydraulic pressure. Also ensures a rapid drop in system pressure when the pedal is released.

Vacuum booster. It is located in the engine compartment on the left, behind the main brake cylinder. Provides approximately 60% of the braking force. It operates using a separate vacuum pump. When the pedal is pressed, the elastic diaphragm of the booster reacts to the change in pressure from the outside air and, due to the pressure difference due to the vacuum behind it created by the vacuum pump, creates additional force, which is transmitted to the main brake cylinder.

Brake fluid. Brake fluid is a mixture of glycol, polyglycolate and other components. It is yellow or transparent, toxic and aggressive towards paintwork, neutral towards metal and rubber parts of the brake system. At –40°C it remains in a liquid state, boiling point is about 290°C.

The disadvantage of brake fluid is its high hygroscopicity. Even with a 2.5% water content, the boiling point drops to 150°C. This can be dangerous under heavy load on the brakes. Near hot brakes, steam bubbles can form in the fluid, which reduces the pressure in the system. The brake pedal "falls through" when pressed; in some cases, it helps to press the pedal several times, "pumping" the brake hydraulic system so that the steam bubbles come out.

Material taken from a web resource: MERCEDESMAN.ru