LMI (Load Moment Indicator) System

Scale and Control Inc. offers the Rayco-Wylie i4500 LMI (Load Moment Indicator) system, ideal for calculating the load weight value by reading the pressure of the crane's lift cylinders. This can be done through the use of pressure transducers on the cylinders to measure load weight, and a cable reel to measure boom length and boom radius. These values are then viewed on the i4500 Display, which can also monitor A2B (Anti-Two-Block), windspeed and other options. The i4500 can also function as a Rated Capacity Indicator system.

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Rayco-Wylie I4500 LMI System

  • Designed for hydraulic and lattice boom applications
  • System can be purchased as either an LMI or as an RCI. Load charts can be programmed into the display
  • The display has a built-in processor, reducing the number of components to be installed in the crane cab
  • The i4500 is available in 3 sizes: 4.3”, 7” or 10”. Can monitor cameras on 7” & 10” displays
  • The color graphical display provides the operator with best in class visibility of the display data when wearing polarized sunglasses
  • Data logging is available via download to USB
  • The i4500 is an ideal solution for applications where system customizations are desired or the need for a larger display is desired. Large integral 2GB memory
  • Flexibility to add inputs and outputs on the CAN bus network
  • The display is IP67 rated, with a temperature range from -4°F to 158°F, an optional extended range display is available from -40°F to 158°F
  • LMI solutions are supplied with two pressure transducers to read the lift cylinder pressure
  • Line riding tensiometers, load pins and dead-end load cells are available for load sensing on RCI applications
  • Various cable reel sizes are available to suit your hydraulic crane type, with integrated angle sensor for monitoring boom length and radius. Electronic angle sensor for lattice boom applications. Available for both LMI & RCI
  • A2B switch integration for Anti-Two-Block monitoring
  • Zoning and work area definition feature
  • Boom tip height monitoring
  • Windspeed and direction option 
​​* Due to specific configurations needed depending on application, contact us for pricing and info on a system to best suit your needs
LMI Sensors
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33R6000 & 33R4000 Series Cable Reel
​R180 Wireless Windspeed Sensor
​R147 Wireless A2B Switch
Load Moment Indicator - LMI
For hydraulic cranes the Load Moment Indicator (LMI) reads its load value using a pair of pressure transducers, which read the cylinder pressures of the lift cylinders. An advantage of an LMI is the weight of the boom is calculated as a part of the load calculation. In doing so, the system will calculate the effects of elements such as wind and ice on available lifting capacity. The system has a digital version of the load chart programmed into it. The cable reel monitors the boom length, with an angle sensor typically integrated into the cable reel to calculate radius: Length x Angle = Radius.

​The down side to an LMI is that the system is calibrated using the empty boom weight of all boom configuration and loaded boom weight for all boom configurations. This can be more costly when repairs or system replacement is required.

On lattice boom cranes, a moment system would see load cells placed in the pendent lines, again weighing the boom as a part of the load calibration. The down side to a lattice moment system is the high cost to calibrate the empty and loaded boom configurations as with the hydraulic system.

Which system should I choose?
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