Created on:2021-09-02 08:48

Port equipment_ Maintenance of hydraulic system of port oil delivery arm

Port equipment_ Maintenance of hydraulic system of port oil delivery arm

The loading and unloading of a huge amount of oil products are completed by port loading and unloading machinery. Oil delivery arm is an indispensable special equipment for loading and unloading oil products and other chemical products in ports and docks. A total of 30 oil delivery arms are used for loading and unloading oil products in a port, all of which are hydraulically driven. Their basic functions include inner arm pitching, inner arm rotation, outer arm extension, floating and quick connector remote control.

(1) Troubleshooting of hydraulic system of oil delivery arm

① Functional fault diagnosis and troubleshooting are shown in the table below. Functional faults are mostly the specific manifestations of hydraulic component faults. The diagnosis process usually requires oil circuit analysis to find out the faulty components, which is a complex process. In practice, some component faults are obvious, and the maintenance position can be determined directly after mastering its characteristics. Therefore, mastering the fault characteristics of components is very necessary to improve the maintenance efficiency.


Common fault causes and troubleshooting measures of oil delivery arm

Fault phenomenon

Possible causes

Fault location and troubleshooting measures

Motor of hydraulic pump station does not start

AC contactor burnt out

Check and replace the AC contactor on the console

Fuse blown

Check and replace the fuse on the console

Thermal relay cut-off

Check the thermal relay on the console, cool the switch, press the reset button on the switch, if the switch continues to cut off, check the cause of overload

Motor or gear pump internal bearing stuck

Rotate by hand, remove the switch and replace the bearing. Pay attention to the concentricity of the gear pump and motor axis during assembly

The coil in the motor is cut off

Check the coil. If damaged, rewind the coil

Starter switch damaged

Check the corresponding switch on which the starter is installed

Loose electrical wiring

Check the wiring, if loose, reconnect

Oil delivery arm does not operate

The oil level in the hydraulic tank is too low

Check the oil level. If it is lower than the rated oil level, fill it

Failure and leakage of sealing ring of hydraulic cylinder

Check and replace the hydraulic cylinder seal

Piston rod bonding

Release the hydraulic pressure in the hydraulic cylinder. If possible, drive it by hand and make the piston rod move freely. If the piston rod is bent, replace it

The oil filter is blocked

Check the oil filter core at the inlet of the hydraulic oil tank. If it is dirty, replace it

Leakage and damage of various valves

Check, clean or replace

The oil delivery arm moves slowly

Hydraulic pump inlet oil filter blocked

Clean the oil filter and oil tank or replace the oil filter and replace the hydraulic shaft

The oil delivery arm moves too fast

There is liquid in the oil pipeline of the inner and outer arms

Drain the liquid

Initial hydraulic system pressure too high

Adjust the safety valve of the pump station to the appropriate pressure

The flow control valve needs to be adjusted

Adjust the flow control valve to achieve the required operating speed




② Troubleshooting of typical components

a. Common faults and troubleshooting of hydraulic cylinder. In actual work, the main fault of the hydraulic cylinder is that there is air in the cylinder due to oil return or other reasons, which crawls during operation. Usually, the exhaust can be completed after repeated operation without load for several strokes. If the exhaust is still poor, open the exhaust plug at the end of the hydraulic cylinder to exhaust. Seal failure of hydraulic cylinder is not common in the hydraulic system of oil delivery arm. It usually shows that you can't establish work pressure. Open the oil return port of the hydraulic cylinder, continue to supply oil after the full stroke, and check whether there is still oil return.

Examples are as follows.

Phenomenon: the action is ineffective or no action, the system pressure cannot reach the set pressure, and the regulating overflow valve does not work.

Preliminary judgment: hydraulic cylinder seal failure.

Diagnosis: open the oil return port of the hydraulic cylinder (ineffective action) and continue to supply oil after the full stroke. A large amount of oil is ejected. It is diagnosed as the sealing failure of the hydraulic cylinder.

Treatment: the fault is eliminated after replacing the hydraulic cylinder seal.

b. Common faults and troubleshooting. Gear pump or vane pump is usually selected as the hydraulic pump of oil delivery arm. Underwater installation is generally adopted, with good cooling performance. The failure rate of the hydraulic pump in the system is very low, in which the failure of the end cover seal causes no pressure rise, and there are many faults such as reverse rotation due to electrical reasons.

Examples are as follows.

Phenomenon: the system pressure cannot reach the set pressure, the regulating overflow valve does not work, and the working sound of the pump is abnormal.

Preliminary judgment: overflow valve failure, hydraulic pump electrical failure, hydraulic pump mechanical failure.

Diagnosis: disassemble the overflow valve for inspection, no abnormality found, troubleshooting; Check the electrical part, no abnormality found, troubleshooting; When the hydraulic pump was disassembled, it was found that the sealing ring of the pump end cover was broken down, and the oil inlet and outlet channels were connected.

Treatment: the fault is eliminated after the hydraulic pump is sealed.

c. Common faults and troubleshooting of control valve. The control valve is the main fault point of the hydraulic system of the oil delivery arm. The main faults are internal leakage caused by blockage and wear caused by oil pollution. Spring failure is also a frequent fault. "

Examples are as follows.

Phenomenon: 4 arm systems, of which 1 outer arm cannot be retracted to the limit, and the system pressure is normal.

Preliminary judgment: there are two main points of internal leakage: one is the 34so directional valve on the console, and the other is the combined valve (throttling and overflow valve).

Diagnosis: replace 34so directional valve, the fault still exists, and it is eliminated; Adjust the combined valve, the fault arm returns to normal, but the same phenomenon occurs in the adjacent arm, which is identified as internal leakage of the combined valve.

Treatment: replace the combination valve and eliminate the fault.

D the most common and troublesome fault diagnosis in the daily maintenance of oil delivery arm is the fault caused by oil pollution.

Examples are as follows.

Phenomenon: the four arm system is operated remotely. When the third arm is operated after the two arm operations are completed, the system pressure suddenly drops below the set pressure, and the oil delivery arm does not work properly.

Preliminary judgment: internal leakage, failure of solenoid valve, overflow valve and pump of selection arm.

Diagnosis: replace the solenoid valve, if the fault still exists, eliminate it; Disassemble the overflow valve for inspection, no abnormality is found, and it is eliminated; Replace the solenoid valve, if the fault still exists, eliminate it; Switch the standby pump, the fault still exists, and it is eliminated.

Secondary diagnosis; The manual directional valve on the console has internal leakage.

Treatment: repeatedly operate the reversing valve and manually / remotely operate the switching valve to eliminate the fault. It was determined that the oil dirt stuck the change-over valve, resulting in internal leakage. After repeatedly operating the change-over valve, the dirt rushed out and the system returned to normal. After the oil change, it was found that there were a lot of viscera in the oil tank and filter, which confirmed the judgment at that time.

In addition to mastering the basic knowledge of oil circuit analysis, the maintenance experience is also very important, but the experience needs to be accumulated for a long time. While studying on-site maintenance skills, improving maintenance level, strengthening management and reducing faults are also important links.

(2) Maintenance and repair means

① According to the fault record of the oil delivery arm, more than 80% of the faults of the hydraulic system of the oil delivery arm are caused by oil pollution. In order to solve this problem, the oil change cycle is formulated, that is, the hydraulic oil is changed every year. The premise of oil change is to timely track the operation status of the system through oil detection means in the stable operation stage, so as to replace the oil in time after the oil quality deteriorates. The oil analyzer with dielectric constant method is purchased. During use, refer to the given "parameter comparison", compare the parameters of new and old oil, and arrange oil change in combination with the comparison with accumulated data.

Due to different oil properties and different operation methods, the results will deviate. Therefore, the monitoring work needs long-term data accumulation as a basis to meet the requirements of condition based maintenance. In practice, when the test data show that the oil quality has a deterioration trend, but it can be used normally, the oil change is also arranged. Although it causes a certain waste, it is an effective measure to ensure the reliable operation of the oil delivery arm when the oil monitoring level is not high.

② Compiling and running hydraulic system fault diagnosis and troubleshooting query software has always been the focus and difficulty of terminal managers. How to quickly find the fault point, determine the fault cause and eliminate it is a problem that technicians have been studying. A query software is established to input the troubleshooting of conventional hydraulic components and the common faults and troubleshooting methods of oil delivery arm accumulated in practice for many years into the database, so as to facilitate the use of technical maintenance personnel in maintenance. This software is suitable for typical component fault diagnosis. New cases and summaries in daily work are input into the computer in time to guide maintenance, which brings great convenience to the work of technicians and maintenance personnel. However, in the actual maintenance, the faults caused by oil pollution often show that the fault phenomenon is complex and non reproducible. The mechanical application of the software can not fully meet the needs, and the software needs to be further supplemented and improved in many aspects such as illustration, inspection and test means.

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