4.2-3 Load moment limit systems
Overload protection OFB
(Electro-hydraulic overload protection with sensing of outer boom position)
This system possesses an LED indicator which shows the current operating state. For normal crane
operation, the diodes are green. When in overload, a red flashing indicator shows what part caused the
overload system to come into action: either the crane, the fly-jib or the limit stop of the rope winch.
If the crane is in the overload range, all moment increasing functions are blocked by means of a
solenoid valve.
The following crane movements are no longer possible:
-main boom:..............................................lowering
-hinged arm above horizontal:...................lowering
-hinged arm below horizontal: ...................raising
-extendable arm:....................................... extending
If fitted:
-rope winch: .............................................. raising
-fly jib:........................................................raising/lowering
-fly jib:.......................................................extending extendable arm
Movements are allowed only after the load moment of the function indicated on the LED have been
reduced.
Before starting work a function check (without load) of the load moment limiting system must
be carried out:
• Extend the boom at maximum speed to the stop. The load moment limiting system must respond
when the stop is reached (Avoid this test position when working).
• The movements previously listed must be blocked.
• The LED for crane now flashes red.
If the overload protection does not respond crane operation is to be
discontinued IMMEDIATELY
and a service workshop visited.
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