Slewing cranes which allowed a rotation of the load and had been thus significantly suited to dockside work appeared as early as 1340. While ashlar blocks had been immediately lifted by sling, lewis or devil’s clamp , different objects have been placed before in containers like pallets, baskets, wood boxes or barrels. Generally, vertical transport could be carried out more safely and inexpensively by cranes than by customary strategies. Typical areas of application were harbors, mines, and, specifically, building sites where the treadwheel crane played a pivotal role in the development of the lofty Gothic cathedrals.
- The crane operator either sits in a cab at the high of the tower or controls the crane by radio distant management from the bottom.
- Tower cranes can even use a hydraulic-powered jack body to lift themselves to add new tower sections with none further other cranes assisting past the initial assembly stage.