The picture on the right shows a ship with three common revolving cranes. The crane house is bolted to a slewing bearing, which lower ring is bolted to a pillar, the foundation, which is part of the ships construction. The slewing bearing is a large double-turning bearing An electric hydraulic motor grabs with its pinion. in the rim of the upper turning ring which is ring
shaped large cog wheel that rotates the crane. Normally the crane cannot rotate unrestrictedly in connection with electrical cables running to and from Container he crane, inside the pedestal.