Port 1 of the valve is connected to the accumulator, port 2 to the tank, and port 3 to the main hydraulic system of the aircraft. Nonreturn valve 4 admits fluid under pressure from the main hydraulic system to the accumulator and prevents flow in the reverse direction. Thus, if the main hydraulic system gets out of order, there is always fluid available under pressure in the accumulator to operate the brakes. When the pressure in the accumulator exceeds a preset value, ball a is pushed to the right off its seat, compressing the helical spring and connecting the accumulator to port 2, which leads to the tank. The maximum pressure in the accumulator is set by means of the spring backing up ball a. The force exerted by the spring is regulated by threaded plug 5.
$3626$SHP,Va$