Service Manual Instruction Manual

SECTION 5 - HYDRAULICS
5-46 – JLG Lift – 3121171
Air Purge Procedure for Non-Calibrated Machines
1. Loosen the hoses on Port #2 (side) of Tower Lift and
Tower Telescope enable valves. This is not necessary on
Main Lift Enable Valve because the orientation of the
valve allows the air to escape.
2. Operate the Main Telescope in until oil appears at Port
#2 of both valves.
3. Tighten both hoses.
4. Raise the Main Boom to approximately 10° above hori-
zontal.
5. Operate the Tower Lift for 25 of the following cycles:
a. Raise the Tower Boom approximately 18”
b. Pause for approximately 2 seconds.
c. Lower the Tower Boom to the boom rest.
d. Pause for approximately 2 seconds.
6. Operate the Tower Telescope for 25 of the following
cycles:
a. Extend the Tower Booms approximately 2’
b. Pause for approximately 2 seconds
c. Fully retract the Tower Booms.
d. Pause for approximately 2 seconds.
Air Purge Procedure for Calibrated Machines
1. Loosen the hoses on Port #2 (side) of Tower Lift and
Tower Telescope enable valves. It is not necessary on
Main Lift Enable Valve because the orientation of the
valve allows the air to escape.
2. Operate the Main Telescope in until oil appears at Port
#2 of both valves.
3. Tighten both hoses.
4. Operate Tower Lift up until Tower Booms begins to Tele-
scope.
5. If an ENABLE VALVE STUCK OPEN fault occurs;
a. Cycle power.
b. Use Auxiliary Power to raise the Tower Boom until
the Tower Telescope star ts to move.
6. Under engine power, operate the Tower Lift for 25 of the
following cycles:
a. Raise the Tower Boom approximately 18”.
b. Pause for approximately 2 seconds.
c. Lower the Tower Boom 18”.
NOTE: Do not pause at this reversal. Quickly switch from Tower
down to Tower up.
7. Raise the Tower Boom 18”, then lower it and stop before
the boom is on the boom rest.
8. Command Tower Boom up until boom moves.
9. Check for faults.
10. If there are faults, continue cycling as in Step #6 until
there are no faults after completing Steps #7 and #8.
11. If there are no faults, position the machine in the stowed
position.