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SECTION 6 - TROUBLESHOOTING
6.13 MAST TROUBLESHOOTING
Platform Will Not Lower Manually
Check For These Obvious Conditions First:
• Is there an obstruction in the mast assembly?
• Is there a restricted hydraulic line (smashed)?
• Are the mast slide pads shimmed properly (not too tight), per Mast Assembly procedure in Service Manual?
STEP
1.
Check to see of the platform will lower from the Ground Control Station in
Ground Control Mode.
2.
Check to see if the lift down valve is opening completely.
3.
Check the flow valve in the lift cylinder for a restriction.
Platform Lift Up And Down - Jerky
Overview Of Procedure
The following procedure suggests areas on the machine which might attribute to erratic movement of the platform during lift
up and down.
Check For These Obvious Conditions First:
• If mast is not running smooth or has tight and rough spots, refer to the Mast Section Rebuild.
• Hydraulic oil level in reservoir tank at full level.
• Hydraulic oil is not milky (presence of water), or foamy (full of air).
STEP
CONTROLS (ELECTRICAL)
1.
Is platform control console, platform enable, up or down pad defective or
worn out?
2.
Loose connections, ground and power.
3.
Valve solenoid keeps opening and closing.
4.
Problem internal to the Ground Control Module.
HYDRAULIC
5.
Is the hydraulic valve working properly.
6.
Pump drive cavatating.
7.
Lift cylinder
6-40
Table 6-44. Platform Will Not Lower Manually.
ACTION
Table 6-45. Platform Lift Up and Down Jerky
ACTION
– JLG Lift –
SPEC
YES
—
Repair or Replace
the Manual Descent
Control Valve
—
Go to Step 3
—
Clean or Replace
Flow Valve
SPEC
YES
—
Replace pad
—
Repair
connection
—
Repair Connection
or Replace Valve
—
Replace Module
—
Go to Step 6
—
Replace Pump
—
Rebuild or Replace
Cylinder
NO
Go to Step 2
Replace the Lift
Down Valve
Consult Factory
NO
Go to Step 2
Go to Step 3
Go to Step 4
Go to Step 5
Replace Valve
Go to Step 7
—
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Troubleshooting
