A slewing wall-bracket crane with a stationary or movable boom. The boom
frame is anchored in upper and lower supports and is most frequently in
the form of a triangulated truss, with guide pulleys for a hoisting
rope fastened to its upper end. It also has mechanisms for lifting and
rotating loads. Boom cranes with a movable boom are equipped with a
mechanism for changing the boom. The lifting capacity of boom cranes is
usually not great (less than 5 tons); because of this only small plants
and shops are equipped with them.