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The hydraulic oil pump is the power source in the hydraulic system. The hydraulic oil pump we are selecting must meet the pressure and flow requirements of the hydraulic system. At the same time, we must fully consider the reliability, life, maintainability, etc. so that the selected hydraulic oil pump can be used in the hydraulic system. Medium and long-term operation.

Characteristics and classification of hydraulic oil pumps

There are many types of hydraulic oil pumps and their characteristics are also very different. Hydraulic oil pumps include vane pumps, gear pumps, plunger pumps and screw pumps, and vane pumps, gear pumps and plunger pumps are generally used in the market. The vane pump can be divided into variable vane pump, heat dissipation variable vane pump, variable vane pump with cooling pump and quantitative vane pump.


1. The hydraulic oil pump body is small and light, easy to use, and high working pressure.

2. Single-stage pumping station: simple structure, higher working pressure can be obtained.

3. Two-stage pumping station: when low pressure, high and low pressure pumps supply oil at the same time, a larger output flow can be obtained; when high pressure, the low pressure pump automatically returns oil without load through the unloading overflow valve. Reduce power consumption.

4. Pressure maintaining function: If there is no leakage in the external oil circuit, stop the pump and maintain the pressure for 5 minutes, and the rated pressure will not drop by more than 5Mpa.


Hydraulic oil pump classification

According to the commonly used pump structure in hydraulic system, it is divided into three types: gear pump, vane pump and plunger pump.

Hydraulic oil pump gear pump

The volume is small, the structure is relatively simple, the cleanliness of the oil is not strictly required, and the price is relatively cheap; but the pump shaft is subject to unbalanced force, severe wear and large leakage.

Hydraulic oil pump vane pump

Divided into double-acting vane pump and single-acting vane pump. This kind of pump has uniform flow, stable operation, low noise, higher working pressure and volumetric efficiency than gear pumps, and more complicated structure than gear pumps.


1. Reasonable design and precision machining of arc blades reduces the compressive stress of the blades on the inner curve of the stator and improves the service life of the stator and blades;

2. The stator adopts advanced high power non-impact transition curve, so that the blade has a good state of motion and stress, ensures good contact between the blade and the stator, and minimizes flow loss, pressure and flow pulsation, and lower noise , Longer life span.

3. The plug-in structure is adopted, and the main internal organs are made into components, and the pump core can be replaced within a few minutes.

Hydraulic oil pump plunger pump

The volumetric efficiency is high, the leakage is small, and it can work under high pressure. It is mostly used in high-power hydraulic systems; but the structure is complex, the material and processing accuracy are high, the price is expensive, and the oil cleanliness is high.  Plunger pumps are generally used when gear pumps and vane pumps cannot meet the requirements. There are other types of hydraulic pumps, such as screw pumps, but their applications are not as common as the above three types.


Matters needing attention in hydraulic oil pump maintenance

1. The oil pump uses No. 20 oil.

2. The oil storage capacity must be within the range above the oil window.

3. Every time when refueling and changing oil, it must be filtered with 80 mesh or more oil filter, and the oil tank must be cleaned when changing. The oil change period is six months.

4. The working oil temperature is 10 degrees Celsius to 50 degrees Celsius.

5. Before starting the electric pump, open the bleed nut and set the switch to the unloading position.

6. If the motor temperature is too high during use, stop using it. Use it after cooling down by itself.

7. The hydraulic oil pump has been adjusted before leaving the factory. It must not be adjusted at will. When it needs to be adjusted again, it must be carried out with the help of a pressure gauge.

8. The high-pressure oil pipe is imported from the factory and has passed the 105MPA test. However, because the hose is easily aging, the user needs to check it frequently, usually for six months, and the vortex flowmeter is frequently used for three months. During the check, the pressure test is 87.5MPA. If there is damage, bulge, or leakage, it cannot be used. .

9. Bearings are generally cleaned once every six months, and grease needs to be added during assembly.


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