JLG G12-55A Service Manual - Manual (Page 52)

Boom
3-16 G10-55A, G12-55A
10. Connect fourth boom section extend chain (10) to
clevis at top front of third boom section and adjust to
previously measured setting. Do Not tighten lock nut
at this time.
11. Connect third boom section extend chains (11) to
clevises at top front of second boom section and
adjust to previously measured setting. Do Not
tighten lock nut at this time.
12. Grease all wear pad at rear of the boom using the
grease fittings.
13. Refer to Section 3.7, “Hose Carrier Assembly
Removal/Installation,” for proper boom section
adjustments.
3.6 BOOM SECTION SEPARATION
ADJUSTMENT
1. Start the machine and verify the boom is in a
horizontal (level) position.
2. Extend the boom 4-5 ft (1,2-1,5 m), then fully retract
the boom.
3. Shut machine OFF.
4. Measure the gap (D) between the flat washer at the
extend chain anchor on the top front of the first boom
section and the second boom section. If the gap is
greater that 0.375 in (9.52 mm), the boom chains will
need to be adjusted.
Adjust the extend chain as follows:
1. Loosen the lock nut (1) on each of the extend chains.
2. Tighten adjusting nuts on first boom section until gap
(D) between flat washers and boom is 0.375 in (9,52
mm) maximum. gap must be equal on both chains.
Torque lock nut to 100 lb-ft (135 Nm).
Note: Verify the exposed threads on both extend chain
clevises are kept equal.
3. Tighten the adjusting nut on the second boom
section until the gap (D) between the washer and
boom is 0.375 in (9,52 mm) maximum. Torque the
lock nut to 100 lb-ft (135 Nm).
MY3440
10 11
MY3800
D
1
1