JLG 41AM (3120872) Service Manual - Manual (Page 54)

SECTION 2 - SERVICE PROCEDURES
2-32 – JLG Lift – 3120872
5. Align threaded hole in side of hydraulic cylinder
head with hole in tab on bottom side of cylinder
mounting channel. Secure hydraulic cylinder to cyl-
inder mounting channel tab using a 5/16"-18UNC x
5/8" long hex head bolt and flat washer.
6. Carefully push mast assembly and base assembly
together until the four (4) holes on bottom rear of
mast align with holes in the base frame mast support
crossmember.
7. Attach mast to base using four (4) 3/8"-16UNC x 1"
long hex head bolts, flatwashers, and nuts. (place a
flatwasher under bolt head and nut and mount with
nuts on inside of frame). Apply Loctite #242 to bolt
threads before final tightening of nuts.
8. Locate the two (2) mast support braces, attach to
sides of base frame using a 3/8"-16UNC x 1" long
hex head bolt, nut and flatwashers each brace,
(place a flatwasher under bolt head and nut and
mount with nuts on inside of frame. Use access hole
in bottom of frame to attach nut inside frame).
9. Before setting machine upright on base, install a
short 90° elbow fitting, flow control valve and
another short 90° elbow fitting on the end of the flow
control valve in the extend (left) port on bottom of
hydraulic cylinder. Install a long 90° elbow fitting on
return (right) port. Use sealant tape on fitting
threads. Cap ports until hydraulic lines are installed.
10. Carefully set machine in an upright position on its
base frame wheels.
11. Locate the mast support bracket. Attach mast sup-
port bracket to mounting holes halfway up back of
mast using four (4) 3/8"-16UNC x 2-3/4" long hex
head bolts, locknuts and flatwashers. (Place a flat-
washer under bolt head and nut and mount with nuts
on inside of frame).
12. Using a 4 ft. level, ensure mast is set to vertical
(plumb) on the base frame.
13. When mast is vertical (plumb), attach mast support
braces, (bolted to base and mast support bracket)
using 3/8" - 16UNC x 1" long hex head bolts and lock
nuts..
14. After securing mast to base frame, using 4 ft. level
again check that mast is vertical (plumb) on base
frame.
Mast installation should now be complete.
2.11 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. Also to step each front mast sec-
tion up approximately 11mm (7/16 in.) from the section
behind it to allow clearance for the individual mast section
covers.
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 obtain the 11mm (7/16 in.) step
for mast sections-3 and up. (See Figure 2-6.)
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. To adjust, 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 so it is even with the previous mast section
when the mast is retracted.
NOTE: It is more important that the (threaded ends) studs
protruding on the adjustments are equal side to side
on a mast section, than it is that the tension in the
chains is equal. The chain equalizers will always
assure equal tension, but if the adjustment isn’t
equal as described, the chains may tend to pull to