The working load limit stipulates the maximum load that should be exerted on the block and its connecting fitting.This total load value may be different from the weight being lifted or pulled by a hoisting or hauling system. It is necessary to determine the total load being imposed on each block in the system to properly determine the rated capacity block to be used.
A single sheave block used to change load line direction can be subjected to total loads greatly different from the weight being lifted or pulled. The total load value varies with the angle between the incoming and departing lines to the block.
The following chart indicates the factor to be multiplied by the line pull to obtain the total load on the block.