JLG sky trak mmv Service Manual page 172

Boom
b. Extend Chain Adjustment
Note: Always perform the "Boom Chain Tension Check"
Refer to Section 4.3.6, a. Boom Chain Tension Check,
before adjusting the top boom chain tension.
1. Park the vehicle on level ground. Place the travel
select lever in the [N] NEUTRAL position, place the
neutral lock lever in the [N] NEUTRAL LOCK
position, engage the parking brake switch and raise
the boom to a horizontal (level) position. Retract the
boom completely and shut the vehicle OFF.
2. Adjust the top extend boom chains by tightening the
locknuts (1), located at the rear of the boom (2). Be
sure each locknut is tightened equally, so that each
chain maintains the same tension.
1
2
3. Equal boom extend chain (3) tension can be
checked by the position of the yoke (4) on the outer
boom. The front of the yoke should be parallel with
the front of the front edge of the outer boom.
4. Start the vehicle and cycle the boom in and out
several times. With the boom horizontal, fully extend
the boom and then retract it 2" (51 mm) (one inch
per section). Turn the vehicle OFF.
5. Measure the chain sag. Acceptable boom chain sag
is between 1.5-2.5" (38-64 mm). If the measurement
is less than 1.5" (38 mm); repeat Steps 1-5 until the
sag is within acceptable range.
4.28
Note: If the top boom extend chain sag cannot be
adjusted within the acceptable range of 1.5-2.5"
(38-64 mm), the boom may require extensive adjustment
and/or repair. Contact the JLG Service Department or
the nearest JLG Authorized Service Center (ASC).
1
IMPORTANT: With the boom extended fully, apply
"LUBRIPLATE" Chain & Cable Fluid, "LPS3" or equiva-
lent or equivalent to the two extend chains.
6. Close the rear door.
c. Chain Replacement
IMPORTANT: Chains and clevis' are wear items and
experience the same stress. DO NOT attempt to service or
repair a chain or clevis. Always replace a stretched or
damaged chain or clevis with a new chain assembly,
which includes the chain and both clevis ends.
Extend Chain Removal
OT05002
1. Removal of the extend/retract cylinder is required to
remove the extend chain. Refer to Section 4.3.2, a.
Inner Boom Removal . Follow Steps 1-24.
2. Remove the lower rear wear pads and spacers (5)
from the inner boom.
3. Remove the two elastic locknuts and two washers (6)
from the extend chain clevis'.
3
Model MMV Rev. 12/04
4
OT07702