Load Moment Indicator (AML-L)

Warning

The load moment indicator (AML-L) is intended as an aid to the operator. Under no condition should it be relied upon to replace use of RATED LIFTING CAPACITY CHART and Operating Instructions. Sole reliance upon the load moment indicator aids in place of good operating practice can cause an accident. The operator must exercise caution to assure safety.

The load moment indicator operates properly only when it is used exactly as instructed in this manual. If you do not follow the specified load moment indicator and crane operating procedures, the crane could overturn or be damaged, causing a serious accident. Be sure to observe the following precautions for safe operation.

• Never perform any operation with the load moment indicator deactivated.

• Place the crane on firm and level ground with the outriggers extended and adjust the crane so that it is level (when outriggers extended).

• Before operating on rubber, check that the tires have the specified air pressure. (when outriggers not extended)

• Before starting operation, perform pre-operational checks on the load moment indicator to ensure that it is operating properly.

• Swinging will not stop automatically even if overloading occurs. When lifting a load on rubber, note that the 360-degree capacity is less than the over-front capacity.

When having a load lifted up in the over-front area swing toward over-side area, be extremely careful not to overload the crane. If, when swinging a load toward the over-side area, the moment ratio indication on the load moment indicator exceeds 100% and the alarm buzzer sounds, stop swinging immediately. Then lower the load or swing the boom back.

• When the load moment indicator exceeds the specified value, the alarm will sound intermittently. Slow the crane operation and take great care. (For the specified value, see the "Load Moment Indicator System" section.)

• Do not lift a load on the boom with the jib mounted. If this must be done by unavoidable reasons, a boom lift status, and not a jib lift status, should be selected on the load moment indicator. This kind of operation can be dangerous if the moment ratio exceeds 90%. Watch the bar-type moment ratio indicator carefully, and make sure that it stays within the green zone during the operation.

• When lifting a single load using both the boom and jib, a jib lift status, and not a boom lift status, should be selected on the load moment indicator. (The figure shows a 5° offset angle with the first jib section extended.) Make sure that the weight of the load (including the weight of the load handling devices) is less than the specified rated lifting capacity for the jib. If the load is left held up only by the auxiliary winch wire rope when the main winch wire rope is loosened, the load’s center of gravity moves to give an increased figure in moment display. Take care to overloading.

Configuration and Functions of the Load Moment Indicator System

The load moment indicator (AML-L) system is a safety device provided to prevent overloading of the crane which may cause it to overturn or be damaged. The load moment indicator unit stores the operation mode selected by the operator and the signals from various sensors. Based on the data stored in its memory, the load moment indicator calculates the working and limit moment values and constantly compares the two. When the load moment indicator recognizes that the working moment ratio is approaching or has reached the limit value, it either sets off an alarm or stops any further movement of the crane toward the critical condition. The configuration and functions of the load moment indicator system are described in the following chart and tables.

• When the crane is automatically stopped during a critical operation (hoisting up, boom extension or boom lowering), operate the appropriate controls to move toward the non-critical condition (hoist down, retract boom or raise boom).

• Do not elevate the boom to raise the load clear of the ground. Doing so is dangerous because the crane will not stop automatically even when it is overloaded. Hoist up the load to raise it clear of the ground. Once the load has cleared the ground, stop hoisting and check for safety.

Load Moment Indicator System Configuration

Boom length signal

Boom angle signalMoment ratio signal

Over-front area signalCrane control position signal

Outrigger extension width detector

Display panel

Load moment indicator unit

Stop output when:

Outrigger status

Boom extension halted

Moment ratio exceeds 100% Twoblocking occurs Load moment indicator system error occurs

Boom lowering halted Hoisting up halted

Lift status

Working range limits Operator selection

Number of part-lines of rope

Alarm buzzer External warning lamps (option)

Working range limit signal output

Upper boom angle restricted Lower boom angle restricted

Lifting height restricted Load radius restricted

Rearward stability control activated T21758E-1

Stop Functions

Causes of stopOperation Halted movement

• Two-blocking

• Moment ration

• Boom lift

• Hoisting-up

• Boom lowering exceeds 100 %

• Load moment

• Boom extending indicator system error occurs

• Single top lift

•Jib lift

Alarm Functions

• Boom raising control ConditionAlarm

Rearward stability ical side when Buzzer: Sounds continuously. twoblock has occurred

Operated to crit-Moment display: Displays[Warning:0024].

When anti-Moment display: Displays [Warning:0015] twoblock device is deactivated

Moment ratio isMoment display: Yellow segment is lit. 90 % or more, but Buzzer: Sounds intermittently. less than 100%.

Operated to crit-Moment display: ical side whenDisplays [Warning:0023]. moment ratio isBuzzer: Sounds continuously. 100 % or more.

Load moment indi-Moment display: cator system errorDisplays failure messages. Operated to crit-Moment display: Displays [Warning:0025] ical side when Buzzer: 3 seconds. rearward stability control activated

Working range limit Associated limit lamp flashes. function activatedBuzzer: Sounds continuously.

Controls

Override Key Switch, Override Warning Lamp, Override Push Switch

While the override key switch is ON, the override warning lamp will light.

The load moment indicator stop function will be cancelled while the lamp is lit and the override push switch is pressed.

Take great care of crane operation while pressing the push switch.

Failure Indicator Lamp

The failure indicator lamp comes on to warn that the operator is attempting an operation toward a critical condition (hoisting, boom extending, or boom lowering) while the load moment indicator detects overloading or overhoisting of the hook block.

When this lamp is illuminated, the operation is automatically halted. Shift the operation toward the noncritical condition.

1. Moment ratio mark

The moment ratios on the bargraph are color coded as follows: safe (green), notice(yellow) and limit (red).

2. Moment display

Normally displays a moment ratio on a bargraph. Displays the main hydraulic pressure and accumulator pressure when the display alteration key is held down. Also displays error messages when the load moment indicator or any of its associated devices fail(s).

3. Scroll-up key

Used to see the previous lines of message displayed on the moment display.

4. Scroll-down key

Used to see the next lines of messages displayed on the moment display.