JLG G12-55A Service Manual - Manual (Page 53)

3-19 G10-55A, G12-55A
Boom
4. After adjusting, check to see that the boom sections
and access holes (2) are aligned. If they are not, the
retract chain will need to be adjusted as well.
Adjust the retract chain as follows:
1. Fully retract the boom.
2. Measure the distance between the second boom
section and the third boom section (E). The
dimension should be 0.50-0.75 in (12,7-19,5 mm).
3. Loosen the second to third boom section retract
chain lock nut and adjusting nut (3) as far as
possible.
4. Loosen the third to fourth boom section retract chain
lock nut and adjusting nut (4) as far as possible.
5. Tighten the retract chain adjusting nut (3) until the
proper distance (E) is obtained and proper access
hole alignment (2) is obtained.
6. Torque the lock nut to 100 lb-ft (135 Nm).
7. Recheck the extend chain adjustments and readjust
if necessary.
8. Measure the distance between the third boom
section and fourth boom section (F). The dimension
should be:
G10-55A - 17.5-17.75 in (444,5-451,3 mm)
G12-55A - 18.5-18.75 in (469,9-476,7 mm)
9. Tighten the retract chain adjusting nut (4) until the
proper distance (F) is obtained and proper access
hole alignment (2) is obtained.
10. Torque the lock nuts to 100 lb-ft (135 Nm).
11. Re-adjust the extend chains as needed.
MY3820
2
F
MY3790 E
MY3810
3
4
Note: BOTTOM OF BOOM SHOWN
WITH EXTEND/RETRACT CYLINDER
REMOVED FOR CLARITY