Figure 6-20. - Determination of single-choker hitch sling capacity.

CHAIN SAFE WORKING LOADS

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

Where:

D = Smallest diameter measured in inches

SWL = Safe working load in tons

Example:

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.