Rexroth hydraulic pumps include gear pumps, vane pumps, screw pumps, axial piston pumps and radial piston pumps. The selection of these Rexroth hydraulic pumps should be based on a comprehensive analysis of the main engine's operating conditions, power size, component efficiency and working performance, and a reasonable selection. First, when selecting a Rexroth hydraulic pump, it should first meet the requirements of the hydraulic system, such as flow rate and working pressure. At the same time, the performance and cost of Rexroth hydraulic pumps are comprehensively analyzed to determine the form of Rexroth hydraulic pumps. 2. When determining the type of Rexroth hydraulic pump, consider making the pump have a certain pressure reserve. Generally, the rated working pressure of Rexroth hydraulic pump should be 10%-20% higher than the maximum working pressure of the system. Third, when selecting the speed of the Rexroth hydraulic pump, comprehensive consideration should be given to the requirements of the host and the allowable speed, life and reliability of the Rexroth hydraulic pump. Increasing the speed (pump speed higher than the rated speed) will cause insufficient oil absorption of the Rexroth hydraulic pump, reduce the service life, and even damage the Rexroth hydraulic pump in advance.