If the radius increases while the load remains the same, what happens to the crane's stability?

• A. It decreases
• B. It increases
• C. It remains the same
• D. It becomes unpredictable

Answer: (A)

Stability in a crane hinges on the balance between the overturning moment caused by the load and the resisting forces from the base, counterweights, and support. The overturning moment is the weight of the load multiplied by its horizontal distance from the crane’s base (the radius). If you keep the load the same but move it farther out, that moment increases directly in proportion to the radius. The resisting moment from the base and counterweights doesn’t automatically grow just because the load is farther away, so the crane becomes more prone to tipping as the radius increases. In short, with the load unchanged, increasing radius reduces stability because the tipping tendency increases while the stabilizing forces stay the same.