Abstract:When the variable pump hydraulic system was in the working condition of acceleration or deceleration, high-pressure peak value would be produced to make the high-pressure relief valve run frequently, which led the system power loss and heat generation, by aiming of this, using a pressure cut-off valve with pressure regulatory function was present, and theoretical analysis of it was made. By taking the hydraulic system of tractor for Chongqing rail transit Line 3 as a research object, modeling and simulation were conducted in AMESim. The simulation results show that the valve has good dynamic and static characteristics, which is used to adjust the variable pump displacement well and avoid the high-pressure peak value, reducing the energy loss caused by the overflow action of high-pressure relief valve effectively. So it has broad prospects for development.