| The outrigger, often referred to
as a “look out” by window cleaners, functions much like a
low profile davit, its beam just clearing the top of the roof parapet,
except the outrigger is a beam with a fulcrum and a rear tie-down anchor.
Used in pairs for supporting a long platform or singularly when suspending
a cage or chair from its outboard end, the outrigger may be tied down
to a roof anchor. All counterweighted outriggers, typically used for construction
applications, must be tied to an independent roof anchor and shall have
lateral stability to prevent roll over in case of an accidental lateral
load.
Buildings featuring projections out from the
vertical face, such as cornices, ledges, “eyebrows” or fins,
create difficulty for the stage to maintain contact with the building.
These sleeves act as the top side of the sleeve, prohibiting the wire
and its fitting to fall through. Drop thru sleeves, with a four to one
safety factor, must be designed by an engineer capable of analyzing the
sleeve, its attachment to the ledge, and identifying its overall effect
on the cornice. The drop thru concept only works for powered, ground rigged
equipment. |
