1. Because the rolling body of this motor is replaced by a steel ball rather than two or more rollers and beams commonly used in inner curve hydraulic motors, it is simple in structure, reliable in performance and greatly reduced in volume or weight. 2. A small kinematics pair inertia and a hard steel ball make this motor continuously work during the rotation at higher speed and under stronger impact load. 3. It has higher mechanical and volumetric efficiency for its small friction pair, oil feed shaft balanced with roller, piston pair capable of static pressure balance and good lubrication and coated high pressure sealing oil on soft plastic mat. 4. As the oil feed shaft and stator are in rigid connection, the oil pipeline of this model can be connected with steel pipe 5. As this model has variable displacement duel and trinal speeds, it is wider in speed regulating range 6. Simple structure and easy maintenance 7. The output shaft of the standard model can only endure the torque rather than outside radial and axial force
