1) The document discusses the importance of verifying the accuracy of load moment indicators (LMIs) on cranes through simple daily checks against known benchmark values. 2) It provides instructions for creating reference points and recording boom length and angle readings from the LMI to use as benchmarks when the crane is setup and leveled. 3) Daily verification involves placing the hook over the reference point and checking that the boom length and angle readings match the recorded benchmark values, ensuring the LMI readings remain accurate. Any deviations would require further inspection.

1. Blog
It’s no doubt that the best start to a safe productive day is with a qualified operator and a complete
pre-operational inspection of your crane. However we want to submit another layer of checks for you
to consider. It’s not enough just to go through a check list to make sure each piece of equipment is
not just turned on and working. Today mobile cranes have state-of-the-art Load Moment Indicators
(LMI) that require a method to ensure the accuracy of their measurements and readouts.
Comparing known values against the readings is an easy way to ensure
all indicators and readouts are accurate while providing that extra peace
of mind. How do you know that the 45’radius, the 30-degree angle, and
the 1,500 lbs. load weight reported on the LMI is correct if you don’t verify
your equipment?
Here is a simple check that will allow you to
easily verify the LMI every day or if ever there
is a question of an LMI’s accuracy. The first time
this exercise is set up it will take a few extra steps, after the initial readings
are recorded, each day it will go much quicker.
One Time Set-Up
The first step is to create a point of reference and determine its radius
with a physical horizontal measurement. On hydraulic mobile cranes with
outrigger systems, extend the outriggers and level the machine as you
would to start work. Take a given outrigger and measure the radius to
the top of the outrigger jack/cylinder and make that radius the point for
reference.
When working with longer, fixed-boom cranes it will take a little effort to
stake out a proper frame of reference, but once they are set up, the refer-
ence point can be used as long as the crane remains in position. Pedestal
mounted cranes and boom truck cranes are the easiest to set up given their
stationary position with reference to a large deck or bed. Simply measuring
out a given radius or two and permanently marking the deck (or truck bed)
gives a point for reference. This practice can be extended to tower cranes
as well.
The Best Start to a Safe Day – LMI Verification
cranetech.com/blog/lmi
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How do you
know your LMI
is correct if you
don’t verify it?

2. Once the point of reference is created and measured, the next step is to
record the LMI data at several boom lengths and boom angles. First,
with the boom fully retracted place the crane hook over your point of refer-
ence and record the boom angle and boom length from the LMI readout.
These become the benchmarks for your LMI with your boom fully retracted.
Then extend the boom to any amount of boom length (in this example we
will extend to 45’).
Then boom up to re-center the hook on the point of reference and record
the boom angle from the LMI readout. Now you have a benchmark with the
boom extended to 45’. We recommend that these measurements be veri-
fied against the load chart range diagram to make sure they are accurate. If
they are accurate, then write them down (examples below) and keep inside
the crane cab for the next time you check the accuracy of your LMI readout.
If they are not accurate, then record this as a major deficiency in your crane
inspection log book and report it to your superiors for repair.
Daily Check
Now with the benchmarks in place, the LMI can be easily verified during
the pre-operational check, or whenever there is a concern that the LMI
is not working properly. Place the hook over the reference point with the
boom fully retracted. Check the boom angle against the written bench mark, if it is good then extend
the boom to the next noted length and check the boom angle. If the boom angle readouts match the
recorded benchmarks, then you are good to go, knowing your computer and your crane are in sync. If
there is a deviation from the usual benchmarks, then a further inspection would be required.
Sample Notes For Cab
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The Best Start to a Safe Day – LMI Verification
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Safety through Education
800.521.7669 • www.cranetech.com