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How Do Crane Load Moment Indicators (LMIs) Work?

There’s no question that cranes play a vital role in the modern construction industry, completing tasks that would take hours – or even days – in a matter of minutes. However, as with any type of heavy machinery, there are certain hazards and risks involved with crane operations, and even small mistakes or miscalculations can lead to disastrous consequences. The most recent data on crane accidents from the Bureau of Labor Statistics dating back to 2006 shows 72 people lost their lives in crane-related accidents that year.

The causes behind crane accidents are many and varying – generally involving human error such as operating the equipment in less-than-ideal weather conditions, overloading, or other conditions that place excessive stress on the lifting capabilities of the crane.

Many crane-related mishaps could have been and can be prevented by installing and using crane warning systems such as Load Moment Indicators (LMI system). These software-based instruments provide operators with vital information needed to manage their lifts safely. In addition to other functions, LMIs warn the operator of potential overload or contact between the boom tip and the hook of the crane.  They take into account the crane’s rated capacity and optional sensors like wind speed.

Crane Load Moment Indicators: How Do They Work?

An LMI monitors the lift using various sensors and delivers a continuous reading of the machine’s safe operating capacity relative to its load chart for the crane operator. The readings continue to vary as the crane moves through the maneuvers needed for the lift. If the conditions become potentially unsafe at any point, the LMI systems will sound an audible and visual alarm to warn the operator.

LMIs provide information about specific geometrical parameters, such as:

  • The angle of the boom

  • The radius of the hook

  • The length of the boom

  • The weight of the load on the hook

  • The rated capacity at the current configuration

  • The ATB warning alarm

  • The wind speed at the boom tip

The Crane Operator’s Responsibility

While an LMI can be an extremely useful device, it’s important to remember that it’s ultimately just an operational aid that can notify operators of impending overload or two-block conditions that can potentially cause accidents.

The instrument should not be considered a substitute for a good operator’s experience or judgment. Its ultimately the crane operators and project managers who are responsible for safe crane operations, and it’s their job to ensure that all the instructions and warnings provided are understood and observed fully.

Here at Crane Warning Systems Atlanta, we sell technologically advanced crane safety instruments, including crane LMI systems, crane load monitoring systems, and wireless crane anemometer, that enhance the safety and efficiency of lift operations. Get in touch with us today to learn more.

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