Load Moment Indicator (LMI)
An electronic safety device that monitors crane load, boom angle, and radius to warn operators of overload conditions.
In Detail
A Load Moment Indicator (LMI) — also called a Rated Capacity Indicator (RCI) — is an electronic system that continuously monitors the crane's actual load moment (load weight × radius) and compares it to the rated capacity at that configuration. It provides visual and audible warnings as the crane approaches capacity limits, and many systems include automatic shutoff at 100% capacity. LMI systems must be calibrated and tested regularly as part of the inspection program. A malfunctioning or bypassed LMI is a critical deficiency requiring immediate crane shutdown. Modern LMI systems can log operational data for review.
Related Terms
Rated Capacity
The maximum load a crane can safely lift at a given configuration, as specified by the manufacturer's load chart.
Load Chart
A manufacturer-provided chart showing the maximum safe lifting capacities at various boom lengths and radii.
Deficiency
Any condition found during inspection that does not meet the required safety standard or manufacturer specification.