No braking
In the brakes off position the diaphragm of the vacuum-operated servo and valve piston are pressed to the rear end position by the return spring. The same pressure exists on both sides of the diaphragm because an overflow valve in the diaphragm is open. The return spring of the master cylinder is forced to its rear end position. In this position the central valves in the primary and secondary circuits are open and the brake system is kept at depressurized. A stop pin prevents the secondary piston from moving backwards and a circlip prevents the primary piston from moving backward.
The master cylinder and other hydraulic components are filled with brake fluid under zero pressure.
The inlet and outlet valves are in an inactive position in the valve block, i.e. the inlet valves are open and the outlet valves closed.
