If a crane is off level by 1 degree, what percent loss occurs in charted capacity?

If a crane is off level by 1 degree, what percent loss occurs in charted capacity?

• A. 10%
• B. 30%
• C. 5%
• D. 50%

Answer: (B)

Even a small tilt changes how the load acts relative to the crane’s base. The charted capacities assume the crane is perfectly level and the load’s weight is carried straight down through the structure with the outriggers and counterweights in their intended balance. When the crane is off level, that balance is disturbed and the same load creates a larger tipping moment, so the safe lifting limit must be reduced to keep stability margins. For a 1-degree lean, that derating is about thirty percent, meaning you can lift roughly seventy percent of the level-capacity. This effect is influenced by boom height and reach, so the exact deration can vary with configuration, but a 30% loss is the standard derate for a 1-degree tilt.

Even a small tilt changes how the load acts relative to the crane’s base. The charted capacities assume the crane is perfectly level and the load’s weight is carried straight down through the structure with the outriggers and counterweights in their intended balance. When the crane is off level, that balance is disturbed and the same load creates a larger tipping moment, so the safe lifting limit must be reduced to keep stability margins. For a 1-degree lean, that derating is about thirty percent, meaning you can lift roughly seventy percent of the level-capacity. This effect is influenced by boom height and reach, so the exact deration can vary with configuration, but a 30% loss is the standard derate for a 1-degree tilt.