JLG 1250AJP Service Manual - Manual (Page 319)

SECTION 4 - BOOM & PLATFORM
3121171 – JLG Lift – 4-79
16. If the main boom angle sensors are calibrated and
operating properly, the control system will now allow
main lift up/down below main boom angles of +65°.
17. Activate main lift and elevate the boom enough to
gain access to remove the main lift cylinder.
18. Use a crane or other suitable supporting device to
support the weight of the main boom assembly.
NOTE: The main boom assembly weighs approximately
6500 lbs. (2950 kg).
19. Put a nylon strap capable of supporting the weight
of the lift cylinder around the cylinder.
NOTE: The main lift cylinder weighs approximately 785 lbs.
(356 kg).
20. At the barrel end of the cylinder, place blocking
under the lower link and between the upper and
lower links so they do not drop when the pivot pin is
removed.
21. Remove the retaining bolt, keeper pin, and pivot pin
securing the barrel end of the lift cylinder to the
lower link.
22. At the rod end of the cylinder, remove the retaining
bolt, keeper pin, and pivot pin securing the rod end
of the lift cylinder to the boom.
23. Remove the cylinder from the machine.
Installation
1. Using an adequate lifting device, position the main
lift cylinder in place on the machine.
NOTE: The main lift cylinder weighs approximately 785 lbs.
(356 kg).
2. Install the retaining bolt, keeper pin, and pivot pin
securing the barrel end of the lift cylinder to the
lower link.
3. If necessary, refer to Removal and use the analyzer
Service Mode to cycle the cylinder in and out several
times to purge air from the cylinder.
4. At the rod end of the cylinder, install the retaining
bolt, keeper pin, and pivot pin securing the rod end
of the lift cylinder to the boom. It may be necessary
to use the analyzer Service Mode to align the pin.
5. Remove the blocking placed under the lower link
and between the upper and lower links during
removal.
6. Refer to Removal, and use the analyzer Service
Mode procedure to lower the boom.