9-4
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9.2
LOWERING ATTACHMENT TO GROUND
When an engine failure occurs, the attachment can be lowered to the ground in the following procedure.
ABOUT LOWERING THE ATTACHMENT TO THE GROUND
When lowering the attachment to the ground, make sure that there is no one under the attachment before starting
the work. A person could be hit and injured by the attachment being lowered.
1.
At first, if the holding valve is attached to the boom cylinder, loosen lock nut (3) of the port relief valve of holding
valve (1) and loosen adjusting bolt (2).
2.
Loosen lock nut (5) of emergency manual valve (4) at the head side of the boom cylinder and loosen needle
valve (6).
3.
The hydraulic oil at the boom cylinder head side flows to the drain circuit through the orifice and then the boom
lowers slowly.
It will take 4 to 8 minutes until the boom lowers to the ground though it may differ according to the machine
position and the holding pressure.
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