Platform (Mast) Won't Stay Elevated - JLG 10VP Service And Maintenance Manual

Platform (Mast) Won't Stay Elevated

Overview Of Procedure
The following procedure requests that the lift down, dump, and pump internal valves be checked to see if any are stuck
open, it also examines the lift down and dump valve circuits. Also suggests that the lift cylinder packing could be leaking
internally.
Check For These Obvious Conditions First:
• Manual descent valve is closed tight.
STEP
Is the lift down valve stuck open?
1.
2. Check the valve inside the pump, it could be stuck open.
Lift down valves could be open due to incorrect electrical signal.
3.
4. Dump valve could be open due to incorrect electrical signal.
5. Oil could be passing around the lift cylinder bore packing.
3120728
Table 3-29. Platform (Mast) Won't Stay Elevated.
ACTION
– JLG Lift –
SECTION 3 - TROUBLESHOOTING
SPEC YES
Repair or Clean
—
Valve
— Replace Pump
Check Pump
Valve Electrical
—
Circuit
(Table 3-22)
Check Pump
Valve Electrical
—
Circuit
(Table 3-22)
Replace or
— Rebuild the Lift
Cylinder
NO
Go to Step 2
Go to Step 3
Go to Step 4
Go to Step 5
—
3-39