Using slings at an angle can become deadly if that angle is not taken into consideration when selecting the sling to be used. The tension on each leg of the sling is increased as the angle of sling, from horizontal, decreases. It is most desirable for a sling to have a larger angle of lift, approaching 90-degrees. Lifts with angles of less than 30-degrees from horizontal are not recommended. If you can measure the angle of the sling, or the length and height of the sling as rigged, you can determine the properly rated sling for your lift. This may also be called a Tension Factor, but we will refer to this as our Load Angle Factor [L.A.F.].
You can start off by asking yourself the most basic question: What capacity sling do I need?
- Determine the weight that the sling will be lifting; L.A.F.
- Calculate the L.A.F.
- Using the angle from horizontal, read across the Angle Chart to the corresponding number of L.A.F. Column.
- Divide sling length* [L] by sling height* [H]
- Lifting Weight [LW] x the L.A.F.] = Minimum Sling Rating, for a single-leg, for the type of hitch that will be used.
*Measured from the horizontal plane, bearing point to the bearing point on the hoisting hook.
Download the Rigging Section of the Lifting Gear Hire catalog for more information about rigging equipment types and specifications.
Illustration and graph information courtesy of and copyright Jerry Klinke, Acratech, www.acratech.com