Created on:2021-08-25 13:43

Fault diagnosis and maintenance of marine hydraulic equipment_ Ship action fault

Fault diagnosis and maintenance of marine hydraulic equipment_ Ship action fault

Ship action failure - the speed of the actuator is too slow or does not act

(1) Fault phenomenon

During the operation of a wheel, the speed of hatch cover device is normal at the beginning of operation, and then the speed gradually decreases until it cannot work.

(2) Cause analysis

The movement speed of the actuator depends on the amount of oil supplied into the actuator. Therefore, the inlet filter screen of the pump was first disassembled and inspected. It was found that it was covered with black colloid. After washing it off, it was tested. The speed was slightly accelerated, but it still failed to meet the requirements. It is found that with the extension of service time, the oil temperature increases continuously. When it rises to 60 ~ 70 ℃, it can not act. At the same time, the system pressure decreases with the service time. Even if the high point can be adjusted, the speed cannot be improved. Therefore, it is considered that the volumetric efficiency of the pump has been very low. After disassembly, it was found that the wear was serious and the axial and radial clearances exceeded the limit a lot. Renew the gear and the system returns to normal.

At the beginning of operation, the system has low oil temperature, high viscosity and less internal leakage, so the working speed can meet the requirements. With the extension of service time, the increase of oil temperature caused by normal operation, coupled with the heat generated by the energy loss caused by the low volumetric efficiency of the pump itself, accelerate the increase of oil temperature, reduce the viscosity of oil, increase the internal leakage of the pump, and form a vicious circle until the equipment can not work.

(3) Summary

The movement speed of the actuator depends on the flow entering the actuator. Therefore, in case of such fault, first judge the reason for the decrease of flow. It may be that the flow of the hydraulic pump is insufficient or there is no flow at all; It may also be that the system leaks too much and the flow into the actuator is insufficient; It may also be that the pressure adjustment is too low to overcome the load resistance of the working mechanism.

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