JLG 680S, Service And Maintenance Manual

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SECTION 4 - BOOM & PLATFORM
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STEP 4: CALIBRATING THE PLATFORM LEVEL UP AND DOWN
VALVE CRACKPOINTS
NOTE: Since the valve position which allows minimum oil flow
(crackpoint) is dependent on the oil pressure, verify the
proper stand-by pressure as outlined in Section 5.3 prior to
setting the crackpoints.
1. Put machine into “Ground Mode”.
2. Start machine and plug in Analyzer.
3. Go to the “Access Level 2” screen.
4. Enter “33271” to get into Access Level 1 mode.
5. Go to the “Calibrations” menu and hit ENTER.
6. Go to the “Basket U Crkpt” Screen. Hit ENTER.
7. “Calibrate?” prompt should appear. Hit ENTER again.
8. The engine will rise to 1800 rpm.
9. Using UP ARROW, increase the value until you see the
basket up movement. (Typically from 275 – 425).
10. Hit ENTER again. “Cal Complete” message should appear
11. Engine should again return to idle.
12. Hit ESC should return to “Basket U Crkpt” screen.
13. Hit RIGHT ARROW to get to the “Basket D Crkpt” screen.
Hit ENTER.
14. “Calibrate?” prompt should appear. Hit ENTER again.
15. The engine will rise to 1800 rpm.
16. Using UP ARROW, increase the value until you see the
basket down movement. (Typically from 275 – 425).
17. Hit ENTER again. “Cal Complete” message should
appear.
18. Engine should again return to idle.
19. Hit ESC to exit.
20. Cycle power to the machine.
21. The preceding steps will provide acceptable crackpoint
settings for the majority of machines. However, if the
operator can feel small jolts in the platform from the
valve opening during a leveling operation, the crack-
point is likely too high for this machine. A high crack-
point may also lead to “over-leveling”, causing the
platform to drift beyond the set point. An example of
this would be the platform tilting too far backwards
during a Lift Up operation. Therefore, use the following
guidelines to evaluate whether further crackpoint
adjustment is required.
a. Telescope the machine halfway.
b. Perform Lift Up. If the basket leans backward (over
compensates), the Level Down crackpoint is too
high. If the basket leans forward or a BASKET LEVEL-
ING SYSTEM TIMEOUT fault occurs, the Level Down
crackpoint is too low.
c. Perform Lift Down. If the basket leans forward (over
compensates), the Level Up crackpoint is too high. If
the basket leans backwards or the Tilt Cutout Alarm
comes on, the Level Up crackpoint is too low.
22. If Platform Level is slow to respond during Lift com-
mands, causing PLATFORM LEVEL TIMED OUT faults, it
may be necessary to increase the crackpoint settings.
Use the following guidelines to evaluate whether fur-
ther crackpoint adjustment is required.
a. Perform a continued Lift Up command (do not cycle
the joystick on/off repeatedly). If the PLATFORM
LEVEL TIMED OUT fault sets or if Platform Level
Down seems slow to respond, an increase in the
Platform Level Down crackpoint may be necessary.
b. Perform a continued Lift Down command (do not
cycle the joystick on/off repeatedly). If the PLAT-
FORM LEVEL TIMED OUT fault sets or if Platform
Level Up seems slow to respond an increase in the
Platform Level Up crackpoint may be necessary.