The gear set draws oil from the tank through the built-in filter and transfers it to the
valve that regulates the oil pressure to the nozzle line. All oil that does not go through
the nozzle line will be by-passed through the valve back to the return line in two pipe
installation or, if it is a one-pipe installation, back to the suction port in the gear-set;
in that case, the by-pass plug must be removed from the vacuum gauge port and the
return port sealed by steel plug and washer.
The valve also has a cut-off function* as follows :
During starting period when the gear-set speed is increasing, all the oil passes through
a bleed slot in the piston, back to the return. Once the speed reaches a certain value
and the flow can no longer pass through this bleed slot, then the pressure increases
rapidly overcoming the valve spring force and opens the valve.
During the stop sequence, the gear-set speed slows down and the valve closes when
the gear-set capacity is lower than the bleed slot flow.
The cut-on and cut-off speeds depend on the gear-set size and set pressure.