How a Gerotor Motor Works

A gerotor motor is an internal gear motor that has an inner drive gear and an outer driven gear that has one more tooth than the inner gear. The inner gear is supported to a shaft which is connected to a load.

The imbalance in a gerotor motor is resulted by the difference in gear area accessible to hydraulic pressure at he motor inlet.

In the diagram, you see the area that is exposed is the inner gear, it increases at the inlet.

Fluid pressure acting on these unequally exposed teeth, may in return show torque at the motor shaft. The bigger the gear or higher the pressure, you will see more torque in the shaft.

Fluid coming into the rotating group of a gerotor motor is separated from the fluid already in the motor by way of a port plate that has a kidney shaped inlet and outlet ports.

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