JLG 680S Service Manual - Manual (Page 212)

SECTION 4 - BOOM & PLATFORM
4-18 – JLG Lift – 3121234
Lift Cylinder Removal
1. Elevate the boom enough to gain access to the lift
cylinder lower pivot pin.
2. Use an adequate supporting device to support the
weight of the boom and associated components as
shown below.
NOTE: The supporting device must be able to support
approximately 5350 pounds (2430 kg).
3. Tag and disconnect the hydraulic hoses from the lift
cylinder.
4. Use an adequate lifting device to support the lift cyl-
inder.
NOTE: The lift cylinder weighs approximately 618 pounds
(280 kg).
5. Remove the bolt and keeper pin securing the upper
lift cylinder pivot pin and remove the pivot pin.
6. Remove the bolt and keeper pin securing the lower
lift cylinder pivot pin and remove the pivot pin.
7. Using the lifting device, slide the lift cylinder back
enough to allow the cylinder end to clear the attach-
ment point on the boom.
8. Slide the lift cylinder sideways enough to remove it
from the machine.
Lift Cylinder Installation
1. Using an adequate lifting device, position the lift cyl-
inder in the machine in the same manner that it was
removed.
2. Install the lower pivot pin and secure it in place with
the keeper pin and bolt.
3. Connect the hydraulic lines to the cylinder as tagged
during removal.
4. Extend the cylinder rod until it aligns with the attach-
ment point on the boom. Take care not to extend the
cylinder rod too far.
5. Install the upper lift cylinder pivot pin and secure it in
place with the keeper pin and bolt.
6. Remove the supporting device and function check
the boom to make sure the lift cylinder operates
properly and there are no leaks.