JLG 20VP (3120728) Service Manual - Manual (Page 98)

SECTION 3 - TROUBLESHOOTING
3-38 – JLG Lift – 3120728
Mast Noisy When Lifting And Lowering
Overview Of Procedure
This procedure examines components of the mast itself and as well as it’s lifting components for dirt, debris, proper lubrica-
tion and operation.
Table 3-28. Mast Noisy when Lifting and Lowering.
STEP ACTION SPEC YES NO
1. Do slide pads and slide pad channels need to be cleaned of dust,
dirt, or other debris?
—
Clean Pads and
Channels
Go to Step 2
2. Do chain/cables need to be lubricated per JLG specification in the
Service Manual?
—
Lubricate as
Required
Go to Step 3
3. Are the chain/cable sheave wheels dry and need lubrication?
Note: Plastic wheels will howl on the sheave pin when they are dry.
Sheave wheels may seize to the sheave pin and the pin may turn in
the pin retainer blocks.
—
Lubricate or
Replace Sheave
Pins and Wheels
Go to Step 4
4. Are the sequence cables (located on the side of mast) chattering
when the springs are compressed?
Note: This noise is normal at the sequence cable sheave wheels
when the mast is completely lowered. However if the sequence
cable chattering is happening no matter what position the mast is in,
it could be a result of the mast being shimmed to tight or dirt and
debris in the slide pad channels causing the mast to be tight.
—
Clean Slide Pads/
Channels or Re-
shim Mast per
Service Manual
Go to Step 5
5. Is the bore of the lift cylinder dry?
—
Replace Packing
or Lift Cylinder
Go to Step 6
6. Are the bearings in the lift pump motor and pump drive worn?
—
Repair or Replace
Pump
Go to Step 7
7. Are the hydraulic lines vibrating together?
—
Adjust the Posi-
tion of the Lines
Go to Step 8
8. Check if the pump motor is loose to it’s mounting plate.
—
Tighten pump
mounting
fasteners
Go to Step 9
9. Hydraulic oil could be cavatating inside the pump.
—
Repair or Replace
Pump
—