Abstract: The manipulation smoothness, the hydraulic pressure shock, the thermal loading, the unloading oil pressure, and the dynamic response of an electrohydraulic control system with the poppet valves for a tractor were studied indetail. The concept of the dynamic pressure feedback was proposed to solve the strong hydraulic pressure shock in the system and tractor pitch oscillation. The test of the new electrohydranlic control system led to following results: compared with the original control system, the tractor pitch speed caused by the lift of the farm implement reduced from 0.3 to 0.08 rad/s, the peak pressure shock in the hydraulic system decreased from 4.0 to 2.8 MPa, the unloading pressure loss in the integrated control valve block was 0.12 MPa, the hydraulic oil temperature at thermal balance was 38 ℃, the switching frequency of the control system was 5.5 Hz.

Key words: turn and control of fluid, electrohydraulic hitch, leakage, manipulation smoothness, dynamic pressure feedback, poppet valve, pressure loss