In principle the rotation speed of a hydraulic motor is defined by the ratio of the flow rate supplied Q 1 to the displacement of the motor V 2:
The highest rotation speed is reached on fixed displacement motors at Q 1max and on variable displacement motors at the V 2min at which the internal friction can still just be overcome.
The lowest rotation speed is reached if Q 1 is just greater than the leakage, or if the shaft still just runs evenly due to the relative delivery fluctuation of the geometric displacement under pressure (medium torque) (e.g. on axial piston machines with 7 pistons approx. 28 rev/min. and with 9 pistons approx. 16 rev/min.).
At lower rotation speeds the relative delivery fluctuation can be corrected with the aid of a control algorithm via the pivoting angle.