Brake Chamber System Description: The brake chamber system is a hydraulic pressure system that uses brake fluid to transfer pressure back and forth between the master cylinder and the brake calipers. This process makes it possible for drivers to apply braking force when needed. The brake pedal contains an electrical switch, which interacts with the two parts of the brake chamber system - a master cylinder and a brake line-pressure actuator valve assembly. These parts are called a tandem valve . When you press on the brake pedal, this electric switch sends current to a solenoid in the main control unit . This switches another contact wire inside from off to on position. That action connects power from your battery.