Boost Pressure Control

As boost pressure increases, it acts between the boost piston and actuating piston, moving the actuating piston back, which moves the control valve to close the port from the accumulator. The control valve closes the accumulator pressure port when the pedal force and boost force acting on the actuating piston equalize. The return port to the reservoir remains closed. The resulting pressure in the booster is proportional to the pedal force. Low pedal force creates low pressure and high pedal force creates high pressure.