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Some Common Faults of Gear Pump
Views: 175 Update Date: Dec 06 , 2018

Gear pumps occasionally encounter some simple faults when they are used in hydraulic devices. 

If it is found that the oil is not coming from the gear pump during the main engine debugging, first check whether the rotation direction of the gear pump is normal. Gear pump is divided into left and right rotation. If the rotation direction is not right, the pressure oil caused by the volume difference generated by the internal gear pump meshing will cause the oil seal to be washed out and leaked.

1. Pump can not produce oil.

If the main engine debugging found that the gear pump does not come oil, first check whether the rotation direction of the gear pump is correct. Gear pump has left and right rotation, if the rotation direction is not right, the pressure oil caused by the volume difference generated by non-gear meshing will cause oil seal to be washed out and leak. Secondly, check whether the oil filter at the oil inlet end of gear pump is blocked, which will cause difficulty in oil absorption or lack of oil absorption, and produce the phenomenon of oil absorption rubber tube being absorbed.

2. The oil seal is washed out.

(1) The gear pump is not rotating in the right direction. When the rotation direction of the pump is incorrect, the high-pressure oil will directly reach the oil seal, because the low-pressure skeleton oil seal can withstand the pressure of 0.5 MPa at most, so the oil seal will be washed out.

(2) The bearing of gear pump bears the axial force. The generation of axial force is often related to the tight coordination between the extension end of the gear pump shaft and the coupling sleeve. That is, when the pump is installed, the hammer or screw is pulled hard and the pump shaft is subjected to a backward axial force. When the pump shaft rotates, the subsequent axial force will force the wear in the pump to intensify. Because the inner part of the gear pump is sealed by the end face of the gear and the end face of the sleeve, when the wear of the end face of the axial seal is serious, there will be a certain gap in the axial seal of the pump, resulting in the high and low pressure oil chamber and the oil seal rushed out. This situation occurs more frequently in the dump truck industry, mainly due to the misalignment of the coupling sleeve size on the main engine.

(3) The gear pump bears excessive radial force. If the coaxiality of the gear pump is not good when it is installed, the radial force of the pump will exceed the endurance limit of the oil seal, which will cause the leakage of the oil seal. At the same time, it will also cause damage to the floating bearing inside the pump.

3. Insufficient or insufficient pressure

This phenomenon is mostly related to the cleanliness of hydraulic oil, such as incorrect selection of oil or the use of oil cleanliness can not meet the standard requirements, will accelerate the internal wear of the pump, leading to internal leakage.

4. Flow is not up to standard

(1) Intake filter element is too dirty and insufficient to absorb oil; 

(2) the installation height of pump is higher than the self-suction height of pump;

 (3) the suction pipe of gear pump is too thin, which results in large oil suction resistance; 

(4) the leakage of suction nozzle joint causes insufficient oil suction of oil pump. By observing whether there are bubbles in the tank, we can judge whether the system is leaking.

5. Fever

(1) System overload, mainly manifested in high pressure or speed

(2) poor cleanliness of oil, worsening internal wear and tear, resulting in reduced volumetric efficiency and heat generation from leakage and throttling of internal clearance

(3) Excessive fine tubing and high oil flow rate

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