Deck Crane Slew Bearing Rocking Tests


 number of incidents have occurred recently involving failure of the slew bearings of ships鈥 cargo deck cranes, resulting in crane losses and serious injury to personnel.
These failures have been caused by undetected excessive wear in the slew bearings.

Rocking tests
Crane manufacturers generally recommend that 鈥榬ocking tests鈥 are carried out every six months in accordance with their instructions, and that the results are recorded and monitored in order to ensure the wear tolerances remain within the limits permitted by the designers.

Cranes which are particularly at risk are those with single ball race slew bearings. Cranes fitted with this type of slew

bearing must have rocking tests carried out, in accordance with manufacturer鈥檚 instructions, to determine that the amount of wear in the bearing races is within permitted limits.

Although cranes with single ball race slew bearings are considered to be most at risk, rocking tests on all deck cranes,

where recommended by the crane manufacturer, must be carried out and the results must be recorded.

Lloyd鈥檚 Register surveyors are being instructed to review the results of rocking tests at all future Annual Thorough Surveys.

If no rocking test has been carried out in the previous six months, the crane in question will not be certified for further use.

It will also be recommended that the crane is taken out of service and the Lifting Appliance Register will be endorsed accordingly.

Measuring proceadures for wear in slewing bearings for rope luffing cranes.

The slewing bearing is an essential part of the crane and must be well maintained.
Over the years the slewing bearing will have some wear, and to be able to know if there is a need for changing the slewing bearing it is needed to keep a record of the wear.


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