Abstract: A new configuration of two-stage radial piston motor with plate pilot pressure control is proposed to address the problem of low working pressure and significant decrease in volumetric efficiency with increasing pressure in traditional shaft or plate radial piston hydraulic motors. The main stage of this configuration adopts seat valve distribution, and the pilot stage adopts mechanical plate valve distribution. By utilizing the good sealing of the seat valve and the low pressure and flow requirements of the pilot stage, it can effectively reduce the leakage of the distribution pair.A motor model is established based on AMESim simulation software, and the simulation results show that the motor can still maintain high volumetric efficiency under a pressure of 30 MPa. To verify the feasibility of the distribution method and conduct characteristic analysis, a motor prototype is developed and experimental research is conducted. The experimental results shows that the motor can run smoothly at low speeds and has bidirectional rotation function；When the pilot pressure is within 11 MPa, the volumetric efficiency remains above 90% and does not significantly decrease with decreasing speed, verifying the feasibility of the proposed new motor configuration in improving the theoretical working pressure ofthe motor；The main oil circuit of the motor is independent of the pilot stage, so by using a high pilot ratio main valve, the workingpressure of the motor can exceed 30 MPa. A feasible technical route is provided for the development of a new architecture high-pressure radial piston hydraulic motor.

Key words: radial piston motor, two-stage flow distribution, pilot pressure control, low-speed high-pressure and large torque, volumetric efficiency