Share the differences between hydraulic motors and hydraulic pumps

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According to Engineer Li in the hydraulic field, here are the differences between hydraulic motors and hydraulic pumps: The similarities between hydraulic motors and hydraulic pumps are as follows: a. Structurally, the two are similar. b. In principle, hydraulic motors and hydraulic pumps are reversible; when driven by an electric motor, they output hydraulic energy (pressure and flow rate), and in this case they function as hydraulic pumps ； If pressurized oil is supplied and mechanical energy (torque and speed) is output, it becomes a hydraulic motor. c. In terms of working principle, both utilize changes in the sealed working volume to draw in and discharge oil. In a hydraulic pump, oil is drawn in when the working volume increases, and high-pressure oil is discharged when the working volume decreases. In a hydraulic motor, high-pressure oil enters when the working volume increases, and low-pressure oil is discharged when the working volume decreases. Differences between hydraulic motors and hydraulic pumps: a. The output shaft of a hydraulic motor must be able to rotate in both directions, so its structure is symmetrical ； Some hydraulic pumps (such as gear pumps and vane pumps, etc.) have specific requirements regarding their rotation direction; they can only rotate in one direction and their rotation direction cannot be changed arbitrarily. b. A hydraulic pump is a conversion device that transforms the mechanical energy of a motor into hydraulic energy, delivering flow rate and pressure, with a desired high volumetric efficiency ； A hydraulic motor is a device that converts the pressure energy of a liquid into mechanical energy, delivering torque and rotational speed, with the goal of achieving high mechanical efficiency. Therefore, a hydraulic pump is an energy device, while a hydraulic motor is an actuator. c. In addition to the inlet and outlet ports, the hydraulic motor also has a separate port for leakage oil ； Hydraulic pumps generally have only inlet and outlet ports (except for axial piston pumps), and the internally leaking oil is in communication with the inlet port. d. The volumetric efficiency of hydraulic motors is lower than that of hydraulic pumps; generally, hydraulic pumps operate at higher speeds, while hydraulic motors produce lower output speeds. Additionally, the gear pump has a large suction port and a small discharge port, while the gear hydraulic motor has suction and discharge ports of the same size ； The gear ratio of a gear motor is higher than that of a gear pump ； The vanes of a vane pump must be installed at an angle, whereas the vanes of a vane motor are installed radially ； The vanes of a vane motor are pressed against the stator surface by swallow-shaped springs at their roots, whereas the vanes of a vane pump are pressed against the stator surface by the pressure oil and centrifugal force at their roots.