19.5.1 Working Load Limit

A shackle must have a working load limit at least equal to the total load to be imposed upon it; alloy steel shackles will be dimensionally smaller load for load than those of higher tensile steel. The shackle pin and body are designed to be of equal strength. To attain this condition, the pin normally has a slightly larger diameter than the material of the body. If the load on the pin is distributed over its length, or part of its length, the load bearing capacity of the pin is effectively increased but that of the body is not. Distributing the load right across the pin will NOT INCREASE THE STRENGTH OF THE SHACKLE. Standard shackles are designed to take the SWL between the centre of the pin and the bearing point(s) in the crown. (See Figure 19.5.1-1 )