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How to maintain the crane's hydraulic system?

April 11, 2022

The hydraulic system provides power for the operating device of offshore cranes. Proper maintenance of the hydraulic system is very important to improve the operational reliability and delay the service life of the crane. Next OUCO will introduce you how to maintain the hydraulic system of crane.

offshore crane hydraulic oil cooler

offshore crane hydraulic oil cooler


First of all, we have to disassemble the hydraulic system for inspection, the machine should be parked on a clean and level ground and the hydraulic system for pressure relief, there are two methods of pressure relief as follows.

① remove the piston rod end pin, the piston rod completely retracted into the cylinder barrel, and then the piston rod slightly extended

② Turn off the engine, put the bucket on the ground, and wrench the lever back and forth to unload the high pressure oil in the circuit back to the oil tank.


After disassembly, we can clean the hydraulic system. The hydraulic system is generally flushed before it is officially put into use, and the purpose of flushing is to remove contaminants, metal shavings, fibrous compounds, iron filings, etc. that remain in the system, which can cause a series of failures during the first two hours of work, even if they do not completely damage the system.


Therefore, the system oil lines should be cleaned using dry cleaning by cleaning the tank with solvent and then removing the solvent residue with filtered air. Clean all lines in the system. In some cases, it may be necessary to soak pipes and fittings.


Install an oil filter in the line to protect the valve supply and pressure lines. Connect the flash plate to the collector and replace precision valves such as electro-hydraulic servo valves. Ensure that all piping is correctly sized and connected properly.


To flush the system, use an oil filter to filter solid particles. During the flashing process, check the oil filter every 1-2 hours to prevent it from becoming clogged with contaminants. Do not open the bypass at this time. Replace the oil filter as soon as it begins to clog.

offshore crane hydraulic power system

offshore crane hydraulic power system

How to replace the hydraulic oil correctly after cleaning?

First, remove the flange of the oil tank outlet and clean or replace the filter element.

Then, put all the waste oil in the oil pipe clean, pour the new hydraulic oil into the hydraulic oil tank, dismantle the hydraulic oil circuit main pipe, start the engine running at low speed, and make the oil pump start working.

Next, manipulate each institution separately, dismantle the return pipe of each cylinder to rely on hydraulic oil to exclude the old oil in the circuit one by one until the new oil starts to flow out of the return main pipe.

Finally, connect the return pipe with the oil tank, and then replenish the new hydraulic oil to the oil tank, and put it in the specified position!