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SECTION 4 – MACHINE OPERATION
Slack Chain Warning Light/Alarm
When the system detects a slack chain condition, the RED light
indicator at platform control station will illuminate and an audible
alarm will sound.
Slack chain condition is generally caused by the platform or the
jib coming to rest on an obstacle while lowering.
When the slack chain indicator warning is activated, all machine
functions, except mast and jib raising movements are disabled.
Procedure to follow in case the slack chain indicator warning is
activated:
1. Raise the mast or the jib (generally the reverse move-
ment to the one that caused the alarm to be activated).
This will re-tension the chain(s) and stop the alarm.
2. Examine surroundings to identify the cause.
3. Perform the movement which will clear the machine and
prevent contact with the obstacle.
If the examination of the surroundings does not reveal any pos-
sible obstacle, the alarm may have been triggered by the tele-
scopic mast jamming which could be due to:
- A foreign body entering the guiding system.
- A lack of lubrication (see Section 6).
- An incorrect mast adjustment (see the Service Manual).
4-12
IF THE SLACK CHAIN ALARM HAS BEEN TRIGGERED, FAILURE TO FOL-
LOW THE PROCEDURES BELOW CAN CAUSE SERIOUS INJURIES.
DO NOT USE MANUAL DESCENT CONTROLS.
Once it has been determined that the slack chain is not due to the
platform resting on an obstacle, proceed in the following manner:
- If the alarm is still active and if safe to do so, raise the mast
slightly above previous position to deactivate it (and tension
the chains).
- Slew the superstructure so the jib can be lowered.
- Lower the jib.
- Try again to lower the mast.
- If the alarm is no longer actuated: fully lower the mast and
arrange qualified personnel to inspect the machine before it is
used again.
- If the mast has not released itself or if the alarm is still actuated,
appropriate equipment can be used to remove platform occu-
pants and stabilize motion of the machine.
– JLG Lift –
31210162
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