One of our vessels recently called at a high-latitude port in severe winter conditions. In preparation for loading cargo with a shore loader, all the ship’s crane jibs were raised and swung clear of the hatchways. Due to the extreme cold (temperatures were as low as -20C), the cranes’ electro-hydraulic systems were kept running idle for the duration of the short port stay. After completion of the loading, and while attempting to park the cranes back on the jib rests, it was observed that the jibs could not be lowered. Upon further investigation, it was found that the driving shaft of the main hydraulic pump on the cranes had sheared off at the linkage, thus completely immobilising the cranes. As an emergency measure, the jibs were housed by operating the brake release mechanism manually.
Root cause of fault electro-hydraulic system on ship
Despite having taken the precaution of leaving the electro-hydraulic power pack running continuously, it is suspected that the failure to move the crane controls at frequent intervals resulted in inadequate oil circulation and caused the ‘idle’ system oil to become very viscous. Subsequent operation of the controls resulted in sudden overloading of the hydraulic motor and sheared the drive shaft linkage.
How prepare ship electro-hydraulic system to extreme cold weather
In extreme cold weather, hydraulic machinery should be frequently moved in all directions.
Before arrival in extreme cold conditions, hydraulic systems should be carefully inspected, system oil confirmed to be at optimum levels, and condition and oil filter elements renewed or cleaned.
Space and system oil heaters, if fitted, must be in operation. Where absent, and if safety permits, the installation of temporary heaters may also be considered.