Figure 13-36.-Determination of bridle hitch sling capacity.
spreaders end connection should be the same as the
thickness of the shackle pin.
In hoisting with slings, spreader bars are used to
prevent crushing and damaging the load. Spreader bars
are short bars, or pipes, with eyes fastened to each end.
By setting spreader bars in the sling legs above the top
of the load (fig. 13-34), you change the angle of the sling
leg and avoid crushing the load particularly in the upper
Spreader bars are also used in lifting long or
oversized objects to control the sling angle, as shown in
figure 13-35. When spreader bars are used, make sure
you do not overload the end connection. A spreader bar
has a rated capacity that is the same as hooks and
shackles. A good rule of thumb is the thickness of the
Sling Safe Working Loads
Formulas for estimating the loads for most sling
configurations have been developed. These formulas
are based on the safe working load of the single-vertical
hitch of a particular sling. The efficiencies of the end
fittings used also have to be considered when
determining the capacity of the combination.
The formula used to compute the safe working load
(SWL) for a bridle hitch with two, three, or four legs
(fig. 13-36) is SWL (of single-vertical hitch) times H
(Height) divided by L (Length) times 2 = SWL. When