Figure 6-20. - Determination of single-choker hitch sling capacity.
To determine the safe working load on a chain, apply a factor of safety to the breaking strength. The safe working load is ordinarily one-sixth of the breaking strength, giving a safety factor of 6 (table 6-1).
The capacity of an open link chain can be approximated by using the following rule of thumb:
SWL = 8D2 x 1 ton
D = Smallest diameter measured in inches
SWL = Safe working load in tons
Using the rule of thumb, the safe working capacity of a chain with a diameter of 3/4 inch is as follows:
SWL = 8D2 = 8 (3/4)2 = 4.5 tons (or 9,000 lbs)
These figures assume the load is being applied in a straight pull, rather than an impact. An impact load is when an object is suddenly dropped for a distance
Figure 6-21. - Determination of double-choker hitch sling capacity.Continue Reading