Matters needing attention in the process of using hydraulic pump

一、Precautions for hydraulic pump connection

1. The hydraulic pump can be installed with a support or a flange. The pump and the prime mover should use a common base support, and the flange and foundation should have sufficient rigidity. Special attention: Plunger pumps with a flow rate greater than (or equal to) 160L/min should not be installed on the fuel tank.

2. The best hydraulic pump and the prime mover output shaft should be connected by an elastic coupling. It is strictly forbidden to install a pulley or gear to drive the hydraulic pump on the hydraulic pump shaft. If a pulley or gear must be used to connect the pump, a pair should be added. The support is used to install the pulley or gear, and the coaxiality error between the support and the pump shaft should not be greater than Φ0.05mm.

3. The suction pipe should be as short, straight, large and thick as possible. The suction pipe generally needs to be equipped with a coarse filter with a nominal flow rate not less than twice the pump flow rate (the filtering accuracy is generally 80-180μm). The drain pipe of the hydraulic pump should be directly connected to the oil tank, and the oil return back pressure should not be greater than 0.05MPa. The oil suction pipe port and the oil return pipe port of the oil pump must be below 200mm of the lowest oil level of the oil tank. Special attention should be paid to the installation of oil filters on the suction pipe of the plunger pump. The diameter of the stop valve on the suction pipe should be one block larger than the diameter of the suction pipe.

4. The inlet and outlet of the hydraulic pump should be installed firmly, and the sealing device should be reliable. Otherwise, air intake or oil leakage will occur, which will affect the performance of the hydraulic pump.

5. The self-priming height of the hydraulic pump does not exceed 500mm (or the imported vacuum does not exceed 0.03MPa). If a charge pump is used for oil supply, the oil supply pressure must not exceed 0.5MPa. When the oil supply pressure exceeds 0.5MPa, pressure resistance should be used instead. Seal ring. For plunger pumps, the self-priming method should be adopted as far as possible.

6. Before installing the hydraulic pump, check whether the depth of the installation hole is greater than the extension of the shaft of the pump to prevent the shaft jacking phenomenon, otherwise the pump will be burnt.

二、Precautions for using hydraulic pump

1. When the hydraulic pump is started, it should be jog several times. After the oil flow direction and sound are normal, run it at 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 shell.

2. The viscosity of the oil changes under the influence of temperature. As the oil temperature increases, the viscosity decreases. Therefore, the oil temperature must be kept below 60℃. In order 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 better chemical stability and anti-foam performance. 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 oil tank through an oil filter truck (filtering accuracy less than 25μm).

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

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

三、Precautions after replacing the hydraulic pump

Pay attention to the discovery of abnormal phenomena at any time

Abnormal sounds, vibrations, or abnormal signals of the monitoring system must have their causes. When an abnormal phenomenon is found, immediately find the circuit diagram, follow the diagram to find out, and carefully observe whether the abnormal phenomenon is caused by a temporary error. Assess the need for parking treatment. For example, pressure, load, temperature, time, starting and stopping all include the possible causes of abnormal phenomena. It should be analyzed and discussed item by item.

Do not add load immediately after the hydraulic pump is started

The hydraulic pump must be idling for a period of time (approximately 10 minutes to 30 minutes) after it is started, especially when the temperature is very low, it must go through the warming process to make the hydraulic circuit circulate normally and then add the load, and confirm the operation status.

Observe changes in oil temperature

Pay attention to check the maximum and minimum oil temperature changes, and find out the relationship between the oil temperature and the external environment temperature, so that you can know whether the capacity of the cooler and the storage tank are compatible with the surrounding conditions and usage conditions, and troubleshooting of the cooling system Trace can be followed.

Pay attention to the noise of hydraulic pump

The new hydraulic pump has low initial wear and is easily affected by air bubbles and dust. Poor lubrication at high temperatures or overloaded use conditions will cause adverse consequences and cause abnormal effects on the hydraulic pump.

Pay attention to check the display value of the meter class

Observe the pressure gauge display value of the hydraulic circuit at any time, the pressure switch light signal and other vibration conditions and stability, so as to find out whether the hydraulic circuit is functioning normally.

Pay attention to the adjustment in each valve

Fully understand the use of pressure control valves, flow control valves and directional control valves, and pay special attention to the adjustment range and limits. Otherwise, adjustment errors will not only damage the machinery, but also pose a threat to safety.

Check the status of the filter

The filter in the loop should be removed and cleaned regularly, and the status of the filter screen and the dirt adsorbed on the net should be checked, and the quality, quantity and size of the filter should be analyzed, so that the degree of pollution in the loop can be observed, and the source of the pollution can be inferred based on this.

Regularly check changes in hydraulic oil

Check and analyze the deterioration, discoloration and pollution degree of hydraulic oil every one or two months to ensure that the hydraulic transmission medium is normal.

Pay attention to the leakage of the piping

Whether the piping of the hydraulic device is good or not can be seen after a period of operation. Check whether the oil leaks and whether the piping is loose.

Causes of hydraulic pump power loss

There are two types of power loss when hydraulic pumps work. One power loss is volume loss and the other is mechanical loss.

Causes of mechanical loss

①. When the hydraulic pump is working, there is mechanical friction between the relative moving parts, such as between the bearing and the shaft, between the shaft and the seal, and between the vane and the inner wall of the pump, resulting in frictional resistance loss. This loss is related to the output pressure of the hydraulic pump. The higher the output pressure, the greater the frictional resistance loss.

②. When oil flows in the pump, viscous resistance is generated due to the viscosity of the liquid, which also causes mechanical loss. This loss is related to the viscosity of the oil and the speed of the pump. The more viscous the oil and the higher the speed of the pump, the greater the mechanical loss.

Due to the above reasons, the actual input power of the pump is greater than the theoretically required power. The ratio of the theoretical input power of the hydraulic pump to the actual input power is called the mechanical efficiency, which indicates the degree of power loss. The ratio of the output power of the hydraulic pump to the input power is called the total efficiency of the hydraulic pump.

Causes of volume loss

①. Although the oil suction cavity and the oil discharge cavity of the positive displacement hydraulic pump are separated in the pump, there is always a certain gap in the relative movement, so the oil in the high pressure zone in the pump must leak to the low pressure zone through the gap. . The lower the viscosity of hydraulic oil and the higher the pressure, the greater the leakage.

②. During the oil suction process of the hydraulic pump, the suction resistance is too large, the oil is too viscous, or the pump shaft speed is too high, etc., will cause the pump to empty, so that the sealed working volume cannot be filled with oil, that is to say, the hydraulic pump The working chamber is not fully utilized.

Due to the above reasons, the hydraulic pump has volume loss.

However, as long as the pump is designed correctly and used reasonably, the loss caused by the second cause can be overcome, that is, the volume loss of the pump can be reduced.

The ratio of the actual flow rate to the rational flow rate is called the volumetric efficiency, which indicates the degree of volume loss of the hydraulic pump. The volumetric efficiency of a hydraulic pump indicates the degree of volume loss of the hydraulic pump.

If you have any problems with the hydraulic pump during use, please feel free to consult with our professional hydraulic pump company.