Load moment indicators and rated capacity limiters
The safety system that stops a mobile crane overloading itself. How a load moment indicator measures load, radius and angle against the chart, the difference between an indicator and a limiter, and what EN 13000 expects.
7 min read · 2026-07-25
A mobile crane can lift far more than it can safely hold once the load moves out to radius, and the device that keeps it from tipping or collapsing under that overload is the load moment system. It is one of the most important pieces of safety technology on a modern crane, watching the load, the reach and the boom angle in real time and comparing them against the crane's own load chart, ready to warn the operator or stop the machine before it exceeds its rating. The standard that governs these systems on mobile cranes in Europe is EN 13000, and understanding what the system does makes any lift safer.
This guide covers how load moment systems work and the difference between an indicator and a limiter.
It stops the overload before it happens
A load moment system continuously compares the actual load moment against the crane's chart and acts before the rating is exceeded, preventing a tip or collapse rather than recording it.
What it measures
The system runs a constant cycle of measurement and comparison. Sensors gather the actual load weight, the working radius and the boom angle, and feed them to a control unit. The unit uses the crane's pre programmed load chart to calculate the real load moment, which is simply the load multiplied by its radius, and compares it to what the chart permits at that configuration.
| Input | Why it matters |
|---|---|
| Load weight | The mass actually on the hook |
| Working radius | How far the load is from the crane |
| Boom angle | The geometry that sets the chart value |
| Load chart | The rated limit at that configuration |
Real time
constant measurement
Load x radius
the moment it watches
EN 13000
the governing standard
Before
acts before overload
Indicator versus limiter
The two terms are related but not the same, and the difference is about what the system does when the limit is reached. A rated capacity indicator monitors radius, load and rating and warns the operator. A rated capacity limiter goes further: it does not just warn, it actively cuts off the movements that would increase the overload, or stops the machine, so an inattentive operator cannot push past the limit.
| System | What it does |
|---|---|
| Rated capacity indicator | Monitors and warns the operator |
| Rated capacity limiter | Warns and actively limits or cuts movement |
Using it well
- 1
Confirm it works
Check the load moment system is functioning before the lift.
- 2
Set the configuration
Make sure the system has the correct crane setup and chart.
- 3
Heed the warnings
Treat its alerts as the limit, not a suggestion.
- 4
Never bypass it
Defeating the system removes the protection it exists for.
Bypassing it defeats the point
A load moment system that is overridden or ignored offers no protection. It exists to catch the overload an operator cannot judge by eye, so it is treated as a hard limit, never a nuisance to work around.
Our cranes carry working load moment protection and certified operators who respect it. Tell us the lift and we will provide a crane and crew that keep it within the chart.
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