Abstract: Abstract:By means of theoretical calculation and prototype test of the heat dissipation performance of the closed hydraulic running system of a certain type of large slope support haulage truck, the rationality of matching the oil replenishment and flushing flow of the hydraulic system is checked, and compared with the heat dissipation system of the same type of truck, it is clear that the lack of heat dissipation power of the hydraulic oil radiator is the cause of excessive oil temperature. Main cause. Based on the test data, the heat dissipation power of the system is increased by connecting the auxiliary radiator in series and opening the vent. The problem of excessive oil temperature of the vehicle is solved. The prototype has been successfully tested for more than three months. Good application results provide a solution for other similar engineering problems.