Today we will observe the composition of the stator and rotor

BMM, BMP series motor uses a Gerotor

While the rest of the Hanjiu motors use a Geroler

Take BMH, BMS, and BMT as examples. Geroler is composed of Ring, Star, and roller. It is made of alloy materials. The higher the hardness, the longer the wearresisting time. The surface finish is also very important. A smooth surface can help reduce the friction of the stator and rotor. Wear.

Essentially, Geroler's rollers have been added to the lobes of the outer ring of the Orbit gear set. These rollers act as rolling bearings and reduce friction in systems with low fluid viscosity, improve mechanical efficiency and reduce wear.

In addition, the Geroler type usually provides smoother performance at low speeds.

The basic formulas and guidelines for determining whether to use Gerotor or Geroler are as follows:
20 x psi / RPM = SUS (use this formula to determine the minimum fluid viscosity)
RPM = the speed of the output shaft in revolutions per minute
SUS = minimum viscosity in SUS.

The recommended viscosity limits are as follows:
1) The minimum fluid viscosity of the Gerotor Orbit gear set is 100 SUS or the value calculated by the formula 20 psi / RPM = SUS.
2) The minimum fluid viscosity of Geroler Orbit gear sets is 70 SUS. In addition, applications running at speeds below 100 rpm should consider using Geroler motors.

The accessories are not recommended to be used in general, the accessories of the same brand are recommended to be used on the motors of the same brand


If you need help in determining motor efficiency, or motor selection and maintenance, please contact our team.

HANJIU The hydraulic motor expert by your side.