JLG E300 Service Manual - Manual (Page 116)

SECTION 5 - HYDRAULICS
5-20 – JLG Lift – 3120772
Upper Boom Telescope Cylinder Installation
1. Attach a hydraulic power supply to the telescope
cylinder ports. Using suitable supports or lifting
devices at each end of the cylinder, extend the rod
so that the cylinder pin attach holes are the same
distance apart as the boom pin attach holes.
2. Using suitable lifting equipment, carefully lower the
cylinder to the boom assembly.
3. Using another lifting device, support the rod end of
the cylinder and install the cylinder into the boom
assembly.
4. Remove lifting devices from the telescope cylinder.
5. Carefully install the telescope cylinder rod pin #1
through the fly boom and secure it with the retaining
rings.
6. Carefully install the telescope cylinder barrel end to
base, securing cylinder to the base boom with four
(4) bolts and hardware.
7. Remove applicable hydraulic line and port caps and
correctly connect the hydraulic lines to the tele-
scope cylinder. Ensure all hoses are correctly
routed.
8. Remove boom prop and overhead crane. Activate
hydraulic system.
9. Using all applicable safety precautions, operate the
boom functions. Check for correct operation and
hydraulic leaks. Secure as necessary.
10. Check fluid level of hydraulic tank and add as neces-
sary.
5.6 LOWER LIFT CYLINDER BLEEDING
PROCEDURE
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).
2. Lay an oil drip pan under the rod end port block and
crack bleeder open from the fitting 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 Tower boom approx. 1 foot (30.5 cm), 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.
To test, cycle the lower lift function 3-4 times to see if both
cylinders stop at the same time when fully extended.
Figure 5-24. Upper Telescope Cylinder Removal