Sensotronic Brake Control (SBC) is an electrohydraulic brake system developed by Daimler and Bosch. The SBC system was introduced in the class R230 SL, which went on sale in Europe in October 2001. In a hydraulic braking system, the driver applies force through a mechanical link from the pedal to the main brake cylinder. In turn, the master brake cylinder develops hydraulic pressure on the wheels. In contrast, the electrohydraulic brake SBC supplies the brakes with a supply of brake fluid from the high pressure hydraulic tank, which is sufficient for several braking events. A piston pump driven by an electric motor supplies a controlled brake fluid pressure between 140 and 160 bar in the gas diaphragm reservoir.
When the driver presses the brake pedal - or when ESP intervenes to stabilize the vehicle - the SBC control unit calculates the desired target brake pressures on each individual wheel. By using independent pressure modulators, the system regulates the hydraulic pressure on each wheel. These four pressure modulators consist of an inlet valve and an outlet valve, controlled by electronic output stages.
The system uses a travel sensor and a pressure sensor on the pedal to measure the speed and strength of the driver's command. The control unit processes this information and generates the control signals for the wheel pressure modulators. Typically, the master brake cylinder is disengaged from the brake circuit. A pedal travel simulator generates a normal pedal feedback. If the ESP intervenes, the high pressure reservoir supplies the required braking pressure quickly and accurately to the selected wheels without any intervention by the driver.