(1) The selection of hydraulic motor is mainly based on the requirements of the host machine for the hydraulic system, such as torque, speed, working pressure, displacement, shape and connection size, volumetric efficiency, total efficiency, quality, price, supply of goods, convenience of use and maintenance, etc. (2) There are many types of hydraulic motors with different characteristics. For specific purposes and working conditions, refer to the following table to select a suitable hydraulic motor. Low speed motor or high-speed motor acceleration and deceleration device can be selected for low speed operation. The five star hydraulic motor in the swing cylinder shall be selected according to the structure and space conditions, equipment cost, driving torque, etc. (3) After determining the type of motor to be used, several specifications that can meet the requirements can be selected from the hydraulic motor product series (see the table below) according to the required speed and torque, and then a comprehensive analysis can be carried out, that is, first find out (or calculate) the corresponding pressure drop, flow and efficiency by using the characteristic curves of various specifications; Then, the specific specifications of the hydraulic motor of the excavator shall be determined by the technical and economic evaluation. If the original cost is the most important, the motor that meets the torque requirements and makes the system flow smaller and the pressure lower shall be selected, so that the hydraulic source, control valve and pipeline specifications are smaller. If the operation cost is the most important, the motor with high overall efficiency should be selected; If the service life is the most important, the motor with the lowest pressure drop shall be selected, and the final product selected is mostly a compromise of the local plan.