Slewing crane with stationary centre column - has derricking jib with end wheels travelling on circular rail

摘要

The horizontal jib (2) slews about a vertical centre column (1), and also derricks on an axis intersecting at right angles the axis of the column (a-a) and crane support (c-c). The jib ends (2',2") have travel wheels (13,13a), by which they are supported on a circular rail (12) on a fixed upper structure (11). The derricking axis pin can have two wheels (10) travelling on a circular rail (9) on the column. The jib can be prestressed between the wheels, and one of the jib end wheels can be driven, to provide the slewing motion. Alternatively a rack and pinion mechanism may be arranged for this drive.