Detailed Review of Crane Load Moment Indicator (LMI) Technology

This report provides an overview of the Crane Load Moment Indicator (LMI) system, crucial for the safe operation of hydraulic cranes. It details the function of the LMI, which uses transducers to measure load values by sensing pressure in the lift cylinder. The report highlights the advantages of LMI, including the incorporation of boom weight in load calculations and the ability to account for environmental factors like wind and ice. The core components of the LMI system are then discussed, including the Anti-two Block sensor system, which prevents the hook from colliding with the boom; the Angle sensor system, which measures the steering wheel angle; the Angle and length transmitter system, used to measure the boom's extension and angle; the Load plate system, for monitoring heavy loads; and the Wind speed sensor, which ensures safe operation by measuring wind intensity. The report references several sources to support the information provided.

REVIEW OF THE CRANE LMI
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Overview
The Load Moment Indicator LMI is used in hydraulic cranes. LMI in cranes is used in reading
the value of the loads using pairs of transducers which uses the pressure, that in turn reads the
pressure of the cylinder that Is found in the cylinder of the lift (Anon, n.d.). One of the advantages
of the Load Moment Indicator in cranes, the boom weight is included as part of the calculation of
the load in the overall calculation. The capability of the system therefore is able to make
calculations in the elements effect which includes the ice and wind on the capacity of the lifting
which is available.
LMI systems in Cranes
The LMI system in cranes includes the following;
Anti-two Block sensor system
The anti block sensor system in the cranes are used for monitoring of the upper hook of the crane
for the reasons of safety which comes with the same. The sensor disallows the hook of the crane
from crashing off against the head of the boom mainly when the load is being uplifted. The
emergency switches for the pull wire switches with the very special design of pulling in this case
with inclusion of the counterweight fulfillment (Anon, n.d.). The counterweight is applied in this
case for keeping the closed the contact switch. Using the anti block sensor, when the hook block
find its way to the uppermost point, the hook hits the counterweight that rises in return which
opens the contact.
Due to the important function which is performed by the sensor, the switch therefore has to be
very much reliable since the switch is exposed to almost the entire part of the types of weather
hence it has to be very much resistant when it comes into contact with salt water (Anon, n.d.).

Angle sensor system
This is one of the most critical systems in the crane LMI systems. The system is functioned at
measuring the angle position of the steering wheel as well as the rate at which the steering wheel
is able to turn. The sensor has a scan tool which is used for providing the data steering wheel
position and turning in degrees. The system is located in the sensor cluster which is located in the
column of the steering. For the confirmation of data and reduction of redundancy, the crane is
made up of at least two angle sensor systems (Anon, n.d.). The ESC module in the system has to
receive at least two signals for the purpose of confirmation and affirmation of the position of the
steering.
Angle and length transmitter system
This crane system is used for measuring the extension of the telescoping cylinder and the angle of
it in relation of the force of gravity. The angle and the length transmitter system is the used for all
types of cranes. It is functioned at measuring the boom length and the boom angle on the cranes
and the man lifts telescopic. Using this kind of system, harsh environments in the mobile cranes
is therefore removed (Anon, n.d.).
The sensor system contains the cable reel which has approx. 32 feets of the wire which is used for
measuring the length, the resolution length of about 30mm, the angle resolution of 0.2 degrees,
the length accuracy of 30mm, the angle accuracy of 0.2 degrees.
Load plate system
This system is used in cranes which are used for loading very heavy goods such as the steel mills
and the steel plates, coils and the ocean going vessels. the system is used for monitoring the
loading of the plate vessels. The plate load is a loading space where the load is held at the flat top

plate and it is then shifted to another vessel (Anon, n.d.). The system is made up of the following
elements;
It has the ability of creating a strong force for accommodating extended plate which is used for
loading wide ships.
The system has the ability of controlling the wide leg opening which is utilized in the unloading
without the slewing process taking place in each and every cycle.
Wind speed sensor
Naturally, the cranes are designed and developed in such a way that they cannot operate in the
environments of high wind speed for the safety of the cranes and the operator. This is why the
cranes are fitted with wind sensor system which is used for determining the safety of the
operation of the crane. The system measures the intensity of the winds and before and during the
operation process. In most of the cranes, wind alarm system is also fitted in conditions of
escalating winds (Anon, n.d.).

References
Anon, (n.d.). Crane Load Moment Indicator | CLICK HERE. [online] Available at:
http://bodetechnicalservices.com/load-moment-indicator/ [Accessed 2019].
Anon, (n.d.). Crane Load Moment Indicators - Back to Basics. [online] Available at:
http://bodetechnicalservices.com/crane-load-moment-indicators-back-basics/ [Accessed 2019].
Anon, (n.d.). HIRSCHMANN Load Moment Indicator for Crawler Crane HC3901 .... [online]
Available at:
https://www.globalcranes.com/download/manuals/Hirschmann_HC3901_Operation_Manual_ZC
C1100H_20140804.pdf [Accessed 2019].