Sundstrand Sauer Danfoss Series 40 Bypass Valves

In units like these sometimes you need to bypass fluid around the variable displacement pump to let it be moved short distances at low speeds. You can do this by manually operating the bypass valve. When the valve is open, it connects both sides of the pump/motor circuit and allows the motor to turn. And the valve needs to be closed for normal operations to work.
The M25, M35 and M44 PV/PT are integral with the check relief valve assy. The assemblies have to be opened for the bypass valve to work. Usually at 4 revolutions the valves are open. And not to go past 4 revolutions on the valves when they are open.
The M46 is opened when doing 2 revolutions. And again do not go past 2 turns.
If more info is needed on the topic please let us know.
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