JLG E300 Service Manual - Manual (Page 58)

SECTION 3 - CHASSIS & TURNTABLE
3-24 – JLG Lift – 3121253
Verification w/ Analyzer Procedure
The motor controller averages the readings from the right
and left speed sensors and therefore, it can be difficult to
detect if the speed sensors are adjusted properly. Often
operators report that posi-track keeps coming in and out
while driving on level surfaces. This is a sure sign that one
of the two speed sensors is not adjusted properly.
The worst case condition of speed sensor maladjustment
occurs when both sensors are installed in a manner that
allows them to indicate the exact opposite direction that
the machine is traveling. This situation causes the control-
ler to believe that the machine is rolling in the opposite
direction than that selected by the operator. The control-
ler's reaction to this situation is to put more power into the
drive motors to attempt to overcome the fact that it
believes the machine is rolling backwards. This presents
itself as uncontrolled movement in the direction selected
by the operator until the controller recognizes that it is
placing maximum power in the motors and the speed sen-
sors are still reporting movement in the opposite direction.
If either speed sensor is disconnected or faulty, the con-
troller will recognize this condition and immediately report
an error message pertaining to a Left or Right Speed
Encoder Faulty message.
THE FOLLOWING PROCEDURE USING THE ANALYZER WILL HELP
VERIFY THAT THE SPEED SENSORS ARE INSTALLED CORRECTLY.
THIS PROCEDURE REQUIRES A LARGE SPACE CLEAR OF
OBSTRUCTIONS. THE OPERATOR SHOULD BE FAMILIAR WITH
JLG EQUIPMENT AND BE PREPARED TO USE THE FOOTSWITCH
TO STOP THE MACHINE. READ AND UNDERSTAND THIS ENTIRE
PROCEDURE PRIOR TO BEGINNING.
1. Before beginning this procedure ensure that there is
at least 10 ft in front and in back of the machine that
is clear of obstruction. Be sure that all other person-
nel stand clear of the machine during this proce-
dure.
2. Unplug the left speed sensor from the posi-track tilt
module.
3. Power up the machine in platform mode and plug in
the analyzer in the platform.
4. Use the right and left cursor keys on the analyzer to
highlight "DIAGNOSTICS" and press enter.
5. Use the right and left cursor keys on the analyzer to
highlight "DRIVE" and press enter.
6. Use the right and left cursor keys to display "SPEED
0%" on the analyzer.
7. While watching the analyzer display select drive for-
ward. Be ready to remove your foot from the foot-
switch if the machine lunges forward.
8. The analyzer display should ready the following if
the right speed sensor is adjusted properly: "SPEED
20% FWD".
9. If the right speed sensor is adjusted improperly, the
analyzer will display "SPEED 20% REV" and the
machine will lunge forward.
10. Adjust the right speed sensor using the above illus-
tration as a guide until the analyzer displays "SPEED
20% FWD" when forward is selected in the platform.
The percentage displayed is not critical, just the
direction.
11. After obtaining the display in step 10, operate the
machine in both the forward and reverse directions.
The machine should be controllable in both direc-
tions and will only drive at a maximum of creep
speed. The display on the analyzer should match
the direction selected.
12. After completing adjustment of the right sensor, plug
the left sensor into the posi-tilt module.
13. Unplug the right sensor from the power module.
14. Power up the machine in platform mode and plug in
the analyzer in the platform.
15. Use the right and left cursor keys on the analyzer to
highlight diagnostics and press enter.
16. Use the right and left cursor keys on the analyzer to
highlight drive and press enter.
17. Use the right and left cursor keys to display "SPEED
0%" on the analyzer.