Some common fault conditions in vane pump maintenance

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During the maintenance of hydraulic pumps, the issues related to vane pumps generally include high noise (which has been subject to dedicated analysis), pressure fluctuations, drop in system pressure, absence of pressure, and excessively high oil temperature in the system. Pressure fluctuation refers to the instability of pressure in the system when a vane pump is in operation. As long as there are no abnormal noises from the oil pump, this phenomenon is likely due to a problem with the pressure control valve (overflow valve). It is necessary to check whether the valve element of the pressure control valve is worn out or if there are any foreign objects blocking it. If pressure fluctuation is caused by wear and tear of the pump’s components, abnormal noises will be heard during operation of the oil pump. System pressure drop occurs when a vane pump is able to reach the desired pressure during operation, but that pressure gradually decreases, preventing the system from functioning properly. If this phenomenon occurs in a newly installed pump, it is likely due to leaks in the system’s control valves or an excessively high oil temperature. If these problems arise after the pump has been in use for some time, then it is necessary to check whether the upper and lower oil distribution plates are worn (to what extent). If the gap between these plates is too large, or if the oil temperature is too high (preventing the formation of a protective film that seals the oil), or if there are leaks in the control valves, all of these factors can cause a drop in system pressure. By \"no pressure,\" it is meant that there is no pressure in the system when the vane pump is operating. First, it is necessary to check whether hydraulic oil is being discharged from the vane pump; if not, then it is necessary to verify whether the pump is operating in the correct direction, whether the coupling between the motor and the vane pump is functioning properly, and whether the shaft positioning screws are tight and effective. It is also possible that the vanes cannot function properly due to the high viscosity of the hydraulic oil. If hydraulic oil is being discharged, it indicates that the pump itself is generally fine; the problem lies likely in severe leaks in the control valves or a malfunctioning pressure relief valve. An excessively high system oil temperature may be caused by too small pipes in the system, excessive pressure, or an inadequate cooling system, all of which can lead to oil trapping in the vane pump. This results in high temperatures in both the pump body and the system oil. In such cases, it is necessary to increase the size of the system pipes, or reduce the pump’s displacement (by replacing it with a pump with a lower displacement), as well as improving the cooling system to enhance its cooling efficiency.