What is a Load Moment Indicator (LMI) and why is it used?

• A. It calculates load moment and tipping risk in real time to help prevent overload.
• B. It measures wind speed during lifts.
• C. It records maintenance history.
• D. It controls the hydraulic pump automatically.

Answer: (A)

A Load Moment Indicator continually calculates the load moment—load weight times its horizontal distance from the crane’s pivot—using the current configuration, such as boom length, angle, jib extension, and outriggers. It compares that moment to the crane’s rated capacity for that setup and signals when the lift is approaching or beyond safe limits. This real-time feedback helps prevent overload and tipping by letting the operator adjust the load, boom, or stance before a problem occurs. It isn’t primarily about measuring wind speed, recording maintenance history, or directly controlling the hydraulic pump—those are separate functions that support safety in other ways.