The function of the hydraulic pump is to convert the mechanical energy of the power machine (such as an electric motor and an internal combustion engine) into the pressure energy of the liquid. The output flow can be adjusted according to the needs called a variable pump, the flow can not be adjusted called a quantitative pump.

Types of commonly used hydraulic pumps

1. According to whether the flow can be adjusted, it can be divided into the variable pump and quantitative pump. The output flow can be adjusted according to the needs called a variable pump, the flow can not be adjusted called a quantitative pump.

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

Gear pump: small in volume, simple in structure, less strict on oil cleanliness, and cheaper; but the pump shaft is subject to unbalanced force, serious wear, and large leakage.

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 a gear pump, and a more complicated structure than a gear pump.

Plunger pump: high volumetric efficiency, small leakage, can work under high pressure, mostly used in high-power hydraulic systems; but the complex structure, high requirements for materials and processing accuracy, high price, and high requirements for oil cleanliness.

Piston pumps are generally used when gear pumps and vane pumps cannot meet the requirements. There are some other forms of hydraulic pumps, such as screw pumps, etc., but the application is not as common as the above three.

Precautions for the use of hydraulic pumps

1. When the hydraulic pump is started, it should be jogged several times. After the oil flow direction and sound are normal, run it under low pressure for 5-10 minutes, and then put it into normal operation. Before the plunger pump is started, the pump must be filled with clean working oil through the drain port on the casing.

2. The viscosity of the oil is affected by the temperature, and the viscosity of the oil increases with the increase of the oil temperature. Therefore, the oil temperature is required to be kept below 60 °C. To make the hydraulic pump work stably at different working temperatures, the selected oil should be It has oil temperature characteristics that the viscosity is less affected by temperature changes, as well as good chemical stability and anti-foaming properties. It is recommended to use L-HM32 or L-HM46 (GB11118.1-94) anti-wear hydraulic oil.

3. The oil must be clean and must not be mixed with mechanical impurities and corrosive substances. The hydraulic system without a filter device on the oil suction line must be refueled to the fuel tank by an oil filter truck (filtering accuracy less than 25μm).

4. The maximum pressure and maximum speed of the hydraulic pump refer to the allowable peak value in a short period of use. Long-term use should be avoided, otherwise, the life of the hydraulic pump will be affected.

5. The normal working oil temperature of the hydraulic pump is 15-65℃. The maximum temperature on the pump casing is generally 10-20℃ higher than the oil temperature at the pump inlet in the fuel tank. When the oil temperature in the fuel tank reaches 65℃, the upper maximum temperature does not exceed 75 ~ 85 ℃.