Which of the following is not a direct factor in crane stability?

• A. Parts of line
• B. Boom angle
• C. Counterweight
• D. Load weight

Answer: (A)

Stability hinges on resisting overturning moments about the crane’s base. The weight of the load and how far that load is from the base (the lever arm) create the tipping tendency, while the boom angle changes that lever arm and the counterweight provides the opposing stabilizing moment. The lifting lines themselves simply transmit the load; they don’t by themselves alter the balance or tipping moments unless there’s an unusual situation like excessive line weight. So, the parts of line are not a direct factor in crane stability because they don’t change the critical moments that determine whether the crane will tip.