Hydraulic motors can be divided into gear type, vane type, plunger type and other types according to their knot types. According to the rated speed of the hydraulic motor, it is divided into two egories: high speed and low speed. The rated speed higher than 500r/min belongs to the high-speed hydraulic motor, and the rated speed lower than 500r/min belongs to the low-speed hydraulic motor. The basic types of high-speed hydraulic motors are gear type, screw type, vane type and axial piston type. Their main features are high speed, small moment of inertia, easy to start and brake, and high sensitivity of adjustment (speed regulation and reversing). Usually, the output torque of high-speed hydraulic motor is not large, so it is also called high-speed small torque hydraulic motor. The basic type of low-speed hydraulic motor is radial piston type. In addition, there are also low-speed structural types in axial piston type, vane type and gear type. The main characteristics of low-speed hydraulic motors are large displacement, large volume and low speed (sometimes It can reach a few revolutions per minute or even a few tenths of a minute), so it can be directly connected to the working mechanism without a reduction device, which greatly simplifies the transmission mechanism. Usually, the low-speed hydraulic motor has a large output torque, so it is also called low-speed large torque. hydraulic motor.