JLG DVSP Series Service Manual - Manual (Page 154)

SECTION 6 - TROUBLESHOOTING
6-40 – JLG Lift – 3121136
Machine Won’t Drive Straight
Overview Of Procedure
The following procedure examines the drive motor assembly weldments attaching the drive motors to the base frame. Also
internal components of the drive motors, gear box and a check of the components between the gear box and the drive
wheels.
Check For These Obvious Conditions First:
• Battery voltage 24 volts. (Fully charge batteries)
• Nothing is lodged between one of the wheels and the base frame.
• A caster wheel on the front of the machine is seized up, creating resistance.
Table 6-51. Machine Won’t Drive Straight.
STEP ACTION SPEC YES NO
1. Check for the following on the drive assembly, drive attachment
weldments; is bent, has broken welds, or loose hardware.
—
Repair/Replace/
Tighten weldment
Go to Step 2
2. Check for the following on the drive assembly, drive motor mounting
plates; are bent, are square with drive weldments, or is hardware
loose?
—
Repair/Replace/
Tighten weldment
Go to Step 3
3. Check for the following on the drive assembly, drive motor hard-
ware; is hardware loose, flange bearing - bad/loose, slip clutch -
check torque settings or adjustment.
—
Repair/Replace/
Tighten compo-
nent
Go to Step 4
4. Check the left and right drive motor brakes for loose hardware & not
releasing properly.
—
Tighten or Adjust
per procedure
in this
Service Manual
Go to Step 5
5. Is the electrical signal and amperage draw to the drive motors
equal? Check with machine on level surface.
See Table 6-3.
Recheck Steps
1 thru 5
Go to Step 6
6. Check the drive motor brushes, do they need replaced?
—
Replace per
procedure in this
Service Manual
Go to Step 7
7. Calibrate joystick on Platform Control Console per procedure in
Section-4 of this Service Manual. Does this fix the problem?
— Done Go to Step 8
8. Is joystick control defective?
If possible, swap out with another platform control.
—
Repair/Replace
Platform control
Go to Step 9
9. Is the Traction Control Module defective or connections not tight?
If possible, swap out with another Traction Control Module.
—
Tighten Connec-
tions or Replace
Traction Control
Module
Go to Step 10
10. Inside the drive motor gear box check if; the drive shaft is exces-
sively loose & condition of drive shaft bearings.
Are any gears broken or gear teeth excessively worn.
—
Repair/Replace gear box
components per procedure in this
Service Manual