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Introduction
System Components
LMAP Display Unit
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LMAP Computer Unit
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Pressure Transducers
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Extension Reel with length and angle sensors
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Anti Two-Block (ATB) switches
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Cables
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The Load Moment Area Protection (LMAP) system is intended to aid the crane operator by
continuously monitoring the load and warning of an approach to an overload or two-block condition.
Crane functions are monitored by means of high accuracy sensors. The system continuously
compares the load suspended below the boom head with the crane capacity chart stored in the
computer memory. At approach to overload, the system warns by means of audible and visual
alarms. The system can be configured to cause function kick-out by sending a signal to function
disconnect solenoids.
Anti Two Block (ATB)
A switch monitors the approach of the hookblock or overhaul ball to the boom head. The switch is
held in the normal position until the hookblock or overhaul ball raises a weight that is mounted around
the hoist rope. When the weight is raised, it causes the switch to operate. The resultant signal is
sent to the computer via the extension reel causing the ATB alarm to operate and function kick-out to
occur.
Area Alarm
When set, this alarm permits the operator to define the operating zone by only two set points. The
use of this method of setting results in a greatly enhanced working area, and also clearly defines the
operating zone.
Boom Angle Sensor
Boom angle is measured by means of a high accuracy potentiometer, a magnetically dampened
pendulum to prevent erratic voltage changes. It provides a voltage proportional to boom angle. The
boom angle sensor is mounted inside the cable extension reel assembly.
Display
The operator is provided with a continuous display of:
Rated Load
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Actual Load
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Bar Graph showing Percentage of Rated Load
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Radius of the Load
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Boom Angle
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Main Boom Length
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Working Area
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Crane Configuration
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