What is a Load Moment Indicator (LMI) and how does it assist the operator?

• A. An LMI is a device that anchors the load.
• B. An LMI records weather data.
• C. An LMI automatically stops all operations.
• D. An LMI measures load moment and helps prevent tipping by indicating when the load exceeds safe limits for the current configuration.

Answer: (D)

A Load Moment Indicator checks how risky the current lift is by calculating the load moment—the weight of the load times its distance from the crane’s pivot, taking into account the boom angle and other geometry. It compares this to the crane’s rated capacity for the present configuration. When the moment approaches or exceeds the safe limit, the LMI gives warnings and can limit or steer operations, helping the operator adjust by choosing a lighter load, shortening the boom, or repositioning the crane so the lift remains stable. It isn’t a device that anchors the load or records weather data, and while some systems can restrict movement, they don’t automatically stop all operations in every situation.