JLG 19AMI (3120758) Service Manual - Manual (Page 45)

SECTION 2 - SERVICE PROCEDURES
3120758 – JLG Lift – 2-31
2.13 MAST CHAINS/CABLES AND
SEQUENCING CABLES ADJUSTMENT
Mast Chain/Cable Adjustment
The intention of this procedure is to assure equal load dis-
tribution between the individual chains/cables of a mast
section chain/cable set.
Adjust using the following procedure;
1. With mast retracted, step into the platform and
bounce your weight up and down a few times to be
certain platform is at the bottom of travel. Be certain
all chain/cable sets are seated in their sheaves prop-
erly at the top of each mast section.
2. Then with no load in the platform check the side pro-
file of the top of the mast for the amount of adjust-
ment necessary to step the mast sections 7/16 in.
(12mm) for mast sections-3 and up. (See Figure 2-
7.)
NOTE: Mast section-1 is fixed to the base and mast section-
2 is attached to the lift cylinder, these sections
require no adjustment.
3. Adjust one mast section at a time starting from the
back (section-3, section-4, etc.) of the mast and
work forward. (i.e.. if three is OK, then jump to four,
etc.)
4. Elevate the platform until the chain/cable anchor
adjust nuts are accessible at the front and bottom of
each mast section.
NEVER WORK UNDER AN ELEVATED PLATFORM UNTIL PLAT-
FORM HAS BEEN SAFELY RESTRAINED FROM ANY MOVEMENT
BY BLOCKING OR OVERHEAD SLING.
5. Start with the mast section which needs adjustment
and loosen the bottom (jam) nut on each chain/
cable.
6. Tighten (to raise mast section), or loosen (to lower
mast section) the adjusting nut against the anchor
plate on each chain/cable. Adjust the nut the
amount required to raise or lower the top of the mast
section to match the side profile shown in Figure 2-
7. when the mast is retracted. Be certain each chain/
cable pair is adjusted to equal tension. (The
threaded end of the chain/cable will need to be
restrained while tightening the adjust nut to keep the
chain/cable from twisting.)
7. Retract the mast all the way and check if the top of
the mast sections appear as shown in Figure 2-7.
Repeat steps (1) through (7) for remaining mast sec-
tions. ENSURE THAT ALL CHAIN/CABLE PAIRS
HAVE EQUAL TENSION.
8. Once mast section adjustment is completed, apply
loctite #242 to the threads under the (jam) nuts that
were loosened. Then re-tighten the loosened (jam)
nuts until tight against the top (adjust) nut. Chain/
cable should have slight tension but should not be
taut.
Sequencing Cable Adjustment
1. Retract mast completely, and check each sequenc-
ing cable on outside of masts for excessive slack.
Adjust only to remove slack from cable.
2. Tighten nylock-nut just enough to remove excessive
slack from sequencing cable. The springs should
not be compressed more than 25% after adjusting.
3. Run mast through several cycles to verify cable/
chain adjustments and ensure no interference exists
between chain anchor brackets and mast.