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SECTION 2 - PROCEDURES
2.19 MID AND LOWER LIFT CYLINDER
BLEEDING PROCEDURE.
(40/N40/45 ELECTRIC)
NOTE: Bleeding procedure should only be necessary if
rebuilding or replacing lift cylinder.
1. Check oil level in the hydraulic oil tank (all booms
must be retracted). See Figure 2-36 for location of
bleeder fitting in pilot port "P" at rod end of mid cyl-
inder.
2. Lay an oil drip pan under the rod end port block
(Mid Cylinder) and crack bleeder open from the fit-
ting in the port block.
3. From the platform, turn the speed control knob to
the slow position.
4. Lift up very slowly. This will force any air out of the
circuit. If the lower boom is not extending, turn the
speed control up very slowly until the lower boom
starts to move.
5. Raise the lower boom approx. 1 foot (30.48mm),
then close bleeder while the boom is still moving.
6. Lift down all the way.
7. Repeat this procedure until all air has been purged
from the circuit. Re-check the hydraulic oil level.
8. To test, cycle the lower lift function 3-4 times to see if
both cylinders stop at the same time when fully
extended.
Figure 2-38. Port "P" Location.
2-48
2.20 BOOM SYNCHRONIZING PROCEDURE.
(40/N40/45 ELECTRIC)
NOTE: If the Lower Boom assembly does not fully lower:
1. Remove all personnel from the platform.
2. Pull the red knob located under the main control
valve.
3.
From Ground Control, activate the lift control switch,
raise Lower Boom 6 feet (1.83m).
4.
After raising Lower Boom, release the red knob.
5.
Activate Lower Boom Down, fully lower boom.
6.
Repeat step 1 thru 5 if necessary
.
Figure 2-39. Synchronizing Valve.
Figure 2-40. Upright Leveling.
– JLG Lift –
3120743
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