Views: 4 Author: Site Editor Publish Time: 2025-12-22 Origin: Site
What is a Load Moment Indicator (LMI)?
Think of the LMI as the "smart brain" of your tower crane. It’s a sophisticated monitoring system that constantly calculates and displays critical load data in real-time. It ensures the crane is operating within its safe design limits.
What are its main functions and uses?
The core job of the LMI is PREVENTION. It prevents two of the most dangerous crane incidents:
1.Overloading: Exceeding the crane’s maximum rated capacity.
2.Over-moment (Over-radius): Operating the load too far from the mast (exceeding the safe working radius for that load).
3.Its purpose is simple: To protect your people, your equipment, your load, and the entire worksite by giving the operator the data needed to make safe lifts.
What are the key applications and monitoring targets?
On every lift, a modern LMI monitors:
1.Load Weight: Compares actual hook load to the crane’s rated capacity.
2.Working Radius: Measures the horizontal distance from the mast to the load.
3.Load Moment: The most critical calculation (Load x Radius). This is the tipping force on the crane.
4.Hook Height & Angle: (On luffing jib cranes) Monitors the boom angle.
5.Safe Working Range: Displays this visually, often as a "green zone" on a screen.
6.It provides both visual displays and audible alarms (gradual and immediate) to warn the operator of approaching or exceeded limits.
Common Issues & Proactive Maintenance：
1.Sensor Failure: Faulty load cells, angle sensors, or radius sensors. Sign: Inaccurate readings or system errors.
2.Calibration Drift: Over time, readings can drift due to vibration, weather, or wear. Solution: Regular re-calibration by a certified technician.
3.Weather & Environmental Damage: Moisture ingress, extreme temperatures, or lightning strikes can damage electronics.
4.Power Issues: Intermittent power supply or faulty connections causing system resets or shutdowns.
5.Display/Interface Problems: Screens failing or becoming unreadable.
Best Practice Tip: Your LMI is not a "set it and forget it" device. What should you pay attention to regularly?
1.Daily operator checks (visual inspection, function test at start of shift).
2.Scheduled preventative maintenance.
3.Annual certification and calibration as per OEM and regulatory standards (like OSHA, BS, AS).
Why It Matters to You？
1.For Project Managers & Site Supervisors: The LMI is your silent safety supervisor, providing a documented record of lifts and ensuring compliance with safety regulations. It’s a cornerstone of your lift planning.
2.For Crane Operators: It’s your most trusted co-pilot. It provides confidence, enhances precision, and is your first line of defense against catastrophic failure.
3.For Everyone on Site: It’s a fundamental part of the safety culture that ensures everyone goes home at the end of the day.
