Description
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 bypassed through the valve back to the return line in a 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 return port, and the return port must be sealed by a steel plug and washer.
The valve also has a cut-off function as follows:
During the starting period, when the gear-set speed is increasing, all the oil passes through a special flat on the piston back to the return. Once the speed reaches a certain value and the flow can no longer pass through this flat, the pressure increases rapidly, overcoming the valve spring force and opening 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 flat flow.
The cut-on and cut-off speeds depend on the gear-set size and set pressure.
Bleed
Bleeding in two-pipe operation is automatic, but it could be accelerated by loosening the plug in a pressure gauge port.
In one pipe operation, a pressure port must be opened to bleed the system.
