Hydraulic motors are divided into high-speed and low-speed according to their rated speed. Those with rated speed higher than 500r / min belong to high-speed hydraulic motors, and those with rated speed lower than 500r / min belong to low-speed hydraulic motors. There are basic types such as high-speed screw motor, axial piston motor and so on. Their main characteristics are high speed, small moment of inertia, easy to start and brake, high sensitivity of speed regulation and commutation.
Usually, the output torque of high-speed hydraulic motor is not large (only tens of n · m to hundreds of n · m), so it is also called high-speed small torque hydraulic motor. The basic types of high-speed hydraulic motor are radial piston type, such as single acting crankshaft connecting rod type, hydraulic balance type and multi action internal curve type. In addition, in the axial piston type, blade type and gear type, there are also low-speed structure types.
The main characteristics of low-speed hydraulic motor are large displacement, large volume, low speed (sometimes up to a few revolutions per minute or even a few revolutions per minute), so it can be directly connected with the working mechanism, without the need for deceleration device, so that the transmission mechanism is greatly simplified. Generally, the output torque of low-speed hydraulic motor is large (up to thousands of Newton meters to tens of thousands of Newton meters), so it is also called low-speed high torque hydraulic motor. Hydraulic motor can also be divided into gear type, vane type, plunger type and other types according to its structure type.