Deck crane slew bearing rocking tests

A number of incidents have occurred recently involving failure of the slew bearings of ships’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 deck crane bearing manufacturers generally recommend that ‘rocking tests’ 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’s instructions, to determine that the amount of wear in the bearing races is within permitted limits.