End Elevation
Fig 11.—Gantry or Elevated Platform over Footpaths
Stagings.—Stagings are erected in a manner similar to travelling gantries, but are carried more than one storey high ([fig. 12]). It is a form of scaffolding rarely seen, more especially since the introduction of the Scotch derrick system. The timbers are erected to the height of the first runner in the same manner as the frames in [fig. 11]. In order to carry the scaffold higher, horizontal pieces are laid across the scaffold, over the standards, and are made to project 9 or 10 feet on each side of the runners.
On these beams, uprights, as in the first tier, are raised, being connected in like manner, longitudinally by transoms. The rising tiers of standards are strutted by timbers A A, rising from the projecting portion of the beam called the footing piece, which serves in the samemanner as a footing block. The footing piece is supported by struts, B B, rising from the lower standards. The struts B B are in two pieces, being bolted to the sides of the footing pieces and uprights. This allows the shores A A to pass between them.
Front ElevationCross Section
Fig. 12.—Example of Stagings
Strutting within the bays formed by the standards is carried out on each tier with the exception of the top, where braces are fixed, as shown at C.
On the top runners rails are laid for a traveller.
In constructing the foregoing square timber erection, note should be taken of the following points:—
That the uprights of the upper tiers should stand immediately over those of the lower tiers, in order to prevent cross strains on the runners.