What does a Load Moment Indicator (LMI) do?

• A. It forecasts weather.
• B. It tracks fuel consumption.
• C. It calibrates outriggers.
• D. It monitors load, boom angle, and radius and warns or limits lifting when capacity is approached or exceeded.

Answer: (D)

The Load Moment Indicator is all about safe lifting by watching how the crane is configured and how heavy the load is. It continuously tracks the load on the hook, the boom angle, and the radius (how far the load is from the crane’s center). Using that information, it calculates the load moment and compares it to the crane’s rated capacity for the current setup. If the moment gets close to or exceeds the limit, the LMI alerts the operator and can automatically limit or derate the lift to prevent tipping or overload. This real-time feedback matters because a load that’s safe at a short reach and steep boom can become unsafe as the reach increases or the boom angle flattens. The LMI’s job is to keep lifts within safe limits, rather than forecasting weather, tracking fuel, or calibrating outriggers.