Which statement accurately describes the load chart conventions?

• A. The numbers above the bold line are based on the structural strength of the boom
• B. The numbers above the bold line are based on the crane's stability
• C. The numbers below the bold line are based on the weather conditions
• D. The bold line has no defined meaning

Answer: (A)

The load chart shows two different limiting factors for safe lifting: structural strength and stability. The bold line marks the boundary where one factor becomes the controlling limit. Above that line, the numbers reflect the crane’s structural strength—the capacity of the boom and related components to handle the load at that reach. Pushing beyond those values risks bending, breaking, or damaging the crane’s structure. Below the line, the numbers are limited by stability—the crane could tip or become unstable in that configuration even if the structure could handle more weight. Weather conditions or wind aren’t what defines this boundary; those are considered separately in other parts of the charts. So the statement that the numbers above the bold line are based on the crane’s structural strength is correct.