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What is the Difference Between an RCI and an LMI System


A crane used for lifting heavy objects

In the realm of material management and lifting operations, the safety and efficiency of crane equipment remain a top concern for operators and riggers. Thanks to technological advancements, crane operators are adopting newer, better crane safety devices to improve their onsite productivity.

Among many crane warning indicators, a load moment indicator and a rated capacity indicator are the two most popular products currently available in the market. They’re manufactured by different renowned brands such as RaycoWylie and used to improve crane safety worldwide.

Commonly known as an LMI and RCI system, these devices play a crucial role in helping crane operators, spotters, signalers, and riggers comply with safe limits during a lift. Continue reading this blog to learn how the two warning devices are different from each other.

What is a Rated Capacity Indicator?

A Rated Capacity Indicator is a robust, versatile, and assistive crane warning device designed to integrate with crane equipment for rated capacity monitoring. An RCI system measures the force directly applied on the hoist line using load sensors. Most commonly, the sensor used with RCI systems is called a load link for measuring the force being pulled. A crane’s rated capacity is its total load capacity, which must be monitored during a lift to avoid overloading and load slipping.

A Rated Capacity Indicator provides load information and limiting values in real-time, allowing crane operators to optimize their lift’s safety and end-to-end code compliance. It also helps in adhering to manufacturer-specified rated capacities to prevent crane accidents.

An RCI system provides quick and accurate loading information and alerts operators when a load reaches or exceeds safe limits. At Crane Warning Systems Atlanta, you can get your hands on authentic RaycoWylie Rated Capacity Indicators. Their products are available in wired and wireless options to help you choose the right one for your crane.

Key Specifications and Features of a Rated Capacity Indicator

Rated Capacity Indicators perform various functions to improve crane safety during a lift and to keep operators alert and aware of loading limits and safe loading practices.

Monitors Force on the Hoist Linein Real-Time

Whether you install a wired or a wireless RCI system, it will provide real-time information about force being pulled directly on the hoist line keeping the equipment aligned to its crane’s rated capacity.

Multiple Alarms

An RCI system is laced with visual and audible alarms to help operators know when a load reaches the rated capacity threshold or exceeds it.

Accident Prevention

An RCI system is extremely beneficial in reducing crane accident risks and optimizes crane operator safety.

Efficiency Boost

RCI systems are helpful for crane operators in making smart, quick, and timely decisions about crane operations. They generate prompt alerts allowing operators and riggers to halt a lift in case of potential danger.




Different types of lifting equipment

What is a Load Moment Indicator?

A Load Moment Indicator (LMI) is an advanced system designed to enhance and support the core functionalities of an RCI system. Compared to an RCI system, an LMI system measures the force on the boom instead of directly on the hoist line. It calculates the total load being lifted using load pins, which can measure:

  • Pendant line force on a lattice boom crane.

  • The side pressure on the rod and bore of a boom lift cylinder.

In addition, a crane LMI system also provides information about crane boom length, job and hoist functions, angle, load radius, and configuration. It helps crane operators know how much they are lifting compared to how much they are allowed to lift according to the manufacturer’s manual.



The RaycoWylie i4300 system

It integrated various technologies to improve safety surveillance during crane lifts. One may say that a Load Moment Indicator is more efficient than a Rated Capacity Indicator. However, both crane warning devices work best when installed in conjunction. Their capabilities work to their full potential with each other to equip operators and riggers with operational information.

Key Specifications and Features of a Load Moment Indicator

Similar to Rated Capacity Indicators, an LMI system also provides several benefits to crane operators. Some of them are discussed below:

Smart Display

A Load Moment Indicator offers an intelligent load chart display to keep crane operators well aware of safe working loads, crane configuration capabilities, crane lifting conditions, and real-time load details.

Broader Monitoring Scope

Load Moment Indicators encompass a larger, more comprehensive surveillance. It measures and presents a wider set of details about crane loads. This information includes everything from load type and weight to volume, surface mass, boom length, boom angle, and more.



A crane rigger at a construction site

Paired with a crane camera system like the CCS2 and CCS4, an LMI system can maximize your crane personnel and equipment’s onsite safety and mitigate overloading accidents. You can also check the robust LMI indicators available on our product page.

The Main Differences Between RCI and LMI Systems

The key differences between the two products are:

  • An RCI system primarily focuses on measuring the force directly applied on the hoist line, whereas an LMI system calculates the load on the boom. An LMI system offers additional information, such as boom length, angle, and radius, to prevent crane tip-overs.

  • RCIs use sensors to detect the force on the hoist line, and LMI systems accept multiple data inputs to provide a holistic crane load moment.

  • RCIs may only provide audible and visual alarms, but the LMI system also adds load chart displays for better understanding.

In short, the key difference between an LMI and RCI system doesn’t pertain to their hardware capabilities. It actually lies in the way the two devices collect information. Both systems use certain sensors to calculate the load on the boom and the force on the hoist line. An LMI system may also provide an anti-two blocking warning if integrated with the relevant capability.

Now you must be wondering about which crane warning device you should pick for your material lifting equipment. While we recommend crane owners install both devices, if you have to pick one, we suggest you opt for the 2-in-1 RaycoWylie i45000 LMI-RCI system.

This device combines the capabilities of RCI and LMI systems into one product and offers the best of both.

Why You Should Choose Crane Warning Systems Atlanta to Buy Original LMI and RCI Systems

Crane Warning Systems Atlanta is a leading crane safety devices distributor in the US. Our company is RaycoWylie’s authorized seller offering quality crane warning products like RaycoWylie ATB, LMI-RCI, and wireless wind speed indicators. We have worked with numerous crane operators and have helped them achieve higher crane safety standards.

If you’re in the US looking for brand-new, warranty-laced crane safety devices, get in touch with Crane Warning Systems Atlanta right away. We also provide 24/7 technical and on-chat support to customers.

Head over to our website and browse through our free-to-access crane product manuals now.



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