Sundstrand Sauer Danfoss Series 15 Charge Pump

The piston motor and pump usually have a little leak, which in turn in is taken away by the closed loop circuit. It creates fluid loss from the circuit that has to be resolved before cavitation  is an issue. To remedy the problem a fixed displacement pump (gerotor kind) is used. This is driven into the prime mover thru the variable displacement pump shaft. The charge pump gives a preset amount of fluid that is used by the pump/motor circuit as needed to reload leakage losses.

The pump/motor circuit is a closed look and it can be pressurized, tow directional control check valves are required to direct charge pump flow into the low pressure side of the circuit.

Pressure that is in the charge pump circuit is restricted by a factory set, direct operating relief valve. The fluid not being used is let go from the circuit over the valve and passes thru the pump and motor housings and back again to the system reservoir.

If you need help with this topic or any others we discuss on here, please let us know.

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