The reasons for the lack of pressure in gear pumps may include the following:

1. Incorrect rotation direction: If the rotation direction of the gear pump is opposite to the specified direction, it will cause the pump to malfunction. You can readjust the direction by adjusting the power line. ‌

2. Oil suction pipeline problems: Loose oil suction pipelines, stuck one-way valves, or blocked suction pipelines by foreign objects can all affect the oil suction effect of the gear pump. It is necessary to check and adjust the oil suction pipeline to ensure its sealing.

3. Poor sealing of pump body: Poor sealing between the pump body and pump cover of a gear pump can cause excessive internal clearance, increase internal leakage, and reduce vacuum degree. Parts with poor sealing need to be replaced.

4. Oil quantity and temperature issues: Insufficient oil quantity in the oil tank or severe wear of oil pump parts, as well as a decrease in oil viscosity caused by low oil temperature, can all affect the working effect of the gear pump. It is necessary to replace severely worn parts and replenish oil in a timely manner.

5. Blockage of oil suction filter: Blockage of oil suction filter will reduce oil suction efficiency, and it is necessary to regularly clean the oil suction filter.

6. Insufficient system load: When the system load is insufficient to provide the pressure required by the pump, the gear pump cannot function properly. It is necessary to increase the load pressure of the gear pump by adjusting the pipeline and valves.

The solutions include:

1. Adjust the power circuit to ensure the correct rotation direction.

2. Adjust the oil suction pipeline to ensure its sealing.

3. Replace poorly sealed components to ensure good sealing of the pump body.

4. Replace severely worn parts, replenish oil in a timely manner, and maintain the oil temperature within the normal range.

5. Regularly clean the oil suction filter to keep it unobstructed.

6. Increase the load pressure of the gear pump by adjusting the pipeline and valves.