unloading valve
unloading valve

When the pressure regulator is in the operating position as shown here, check valve D is seated, the piston is held down by the spring, and fluid from the power pump flows to the system through external line and check valve E. Check valve D is held on its seat by pressure. The same pressure is transmitted through port B and acts on the bottom of the piston, exerting a force that tends to move the piston up and open the check valve D.
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