Created on:2022-02-18 13:03

Brief introduction of gear hydraulic motor

Brief introduction of gear hydraulic motor

Gear motor has similar advantages to gear pump, such as simple structure, small volume, light weight and low price. Its disadvantages are low efficiency, poor starting performance and serious output speed pulsation, so its application is less. Figure a shows the working principle of gear motor. P is the meshing point of two gears, the tooth height is h, and the distance from the meshing point P to the tooth root is a and B respectively. Since both a and B are less than h, when the pressure oil port acts on the tooth surface, the two gears generate forces Pb (H-A) and Pb (H-B) (P is the input pressure and B is the tooth width), so that the two gears rotate in the direction shown in the figure and drain the oil to the low-pressure chamber.

The structure is also very similar to that of gear pump. Figure B shows the outline drawing of CMFA / FC medium and high pressure gear motor, and figure C shows cm_ Figure D shows the structure diagram of cm-f gear motor. Its structure is basically the same as that of cb-f series gear pump, but they are still different due to the working characteristics of hydraulic motor, which is mainly reflected in: the inlet and outlet oil holes of hydraulic motor are the same to adapt to forward and reverse rotation; There is a separate oil drain port, which needs to be directly returned to the oil tank; There is no axial clearance compensation mechanism and fixed axial clearance is used (but there are gear motors with automatic axial clearance compensation). Like the gear pump, the gear motor is generally used in the occasions of high speed and low torque due to the disadvantages of poor sealing, low volumetric efficiency and poor low-speed stability.


Gear motors are used in engineering machinery, agricultural machinery and forestry machinery. The working pressure of domestic hydraulic motor is generally less than 10MPa, the torque is 17.4 ~ 112N · m, and the speed is about l800r / min. Its models include CM-C, cm-d, cm-e and cm-f involute tooth motors, as well as YMC Cycloidal Tooth internal meshing hydraulic motors.

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