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How to exclude gear pump failure

Gear pumps are generally used for engineering machinery of dirty work environment and general machine tool accuracy is not high, and hydraulic system that the pressure is not too high and the flow is large.

Gear pump advantages:

1) Simple structure, good manufacture ability and low cost.

2) Compared with other same type of pumps, the structure of gear pump is compact, the size is small .

3) Self-priming performance is good. Both in high and low speeds even in the case of the manual can be reliably achieved self-absorption.

4) Speed range is large. Due to the transmission and a gear portion of the pump are substantially in balance, will not produce a large inertial force at high speed.

5) The dirt in the oil of their work is not serious and difficult to bite.

Gear pump disadvantages:

1) Working pressure is low. The pressure on gear, axle and gear shaft is imbalance, the load in the radial direction is large, limiting the increase off its pressure. Gear pump is mainly used in low-voltage systems.

2) A lower volumetric efficiency. This is due to the leakage of a large end face of the gear pump.

3) Flow ripple, causing pressure pulsations, which lets pipes, valves and other pieces emerge vibration and great noise. 

Gear Pump Fault Causes and Remedies:

The transported oil is insufficient and pressure can’t be mentioned highly: 


1. The veer of electromotor is error. 

2. Inhalation pipe or oil filter is stoppage.

3. Axial or radial gap is too large.

4. Caused by each of the junction leakage let air comes into it.

5. Oil viscosity is too high or the oil temperature is too high.


1. Correct motor steering.  

2. Dredge pipe, cleaning filters blocking material is removed, replaced with new oil. 

3. Replace and repair the related parts. 

4. Tightening the screws at each connection, to avoid leaks to prevent air mixing. 

5. Oil changes should be selected according to the temperature rise.

Serious noise and pressure fluctuations:


1. Part of the suction pipe and oil filter is clogged or inlet filter capacity is small.

2. Inhalation tube or shaft seal inhaled air bubbles.

3. Pump and coupling misalignment or abrasions.

4. Precision of gear itself is not high.

5. CB gear pump seal skeleton damage or seal skeleton falls off when install axle. 


1. Remove dirt, so that the suction pipe flow, or switch capacity suitable filter.

2. Add a little oil in the joints or seals, if the noise is reduced, the joints can be tightened or replaced seals, oil return pipe mouth should below the surface of the oil, and the suction pipe to have a certain distance. 

3. Adjustment of concentric, excluding abrasions.

4. Replace the entire training gear.

5. Check seal, when replace if damaged to prevent inhalation of air.

Pump rotation is not flexible or killed:


1. Axial gap and radial clearance is too small.

2. Poor assembly, CB-type cover, and the concentricity of the shaft is not good, the long axis of the spring fastening feet long, the quality of needle sleeve is poor.

3. Pump and motor coupling concentricity is bad.

4. Impurities is inhaled in the oil pump body.


1. Repair related parts. 

2. Reassemble according to the requirements.

3. Adjusted so that the different axes is not more than 0.2mm.

4. Prevent surrounding sand lime, iron and other objects of cooling water into the oil reservoir to keep the oil clean.