Functions of Crane LMI Load Moment Indicator System

LMI is the core mandatory electronic safety system for all mobile & tower cranes, also named Rated Capacity Indicator (RCI). It calculates load moment = load weight × working radius and controls crane operations to prevent crane rollover, boom breakage and load falling caused by overload or over-radius operation, complying with OSHA & international crane safety regulations.

LMI yo

1. Real-time Parameter Monitoring & Cab Display

· Collect data via multiple sensors: actual hook load, boom length, boom elevation angle, working radius, outrigger pressure.

· Show real-time readings on cabin screen: rated lifting capacity, actual load, moment percentage (actual/rated), boom status, safe limit data for operators’ reference.

2. Step-by-step Pre-warning & Alarm Protection

· When actual moment reaches 90% of rated safe moment: trigger visual flashing light + audible buzzer warning to remind operators to reduce load or shorten working radius.

· When moment hits/exceeds 100% rated limit: auto-lock dangerous movements only: stop hoisting upward, boom luffing down, boom telescoping out; still allow safe actions: lower hook, raise boom, retract boom inwards to release overload risk.

3. Working Range & Outrigger Safety Control

· Restrict excessive working radius automatically: longer boom or larger radius cuts down allowable lifting weight per factory load chart preset in LMI program.

· For truck/crawler cranes: monitor outrigger load pressure; forbid heavy lifting if outriggers are uneven or improperly extended.

4. Black Box Data Recording Function

Built-in storage continuously logs operation data: lifting time, load value, moment ratio, alarm & overload events, operator actions. The stored data supports accident investigation, equipment maintenance and site safety management.

5. System Self-diagnosis

Automatically check sensors, wiring and controller at startup and during running. Pop up fault alert on screen once sensor failure or circuit breakdown is detected to forbid unsafe operation with defective LMI.

6. Extended Intelligent Functions (Modern LMI)

· Wind speed linkage: stop boom slewing automatically when ambient wind exceeds safe threshold for tower/ship cranes.

· Remote IoT monitoring: upload operation data to cloud platform for fleet management and remote fault diagnosis.