JLG 41AM (3120872) Service Manual - Manual (Page 53)

SECTION 2 - SERVICE PROCEDURES
3120872 – JLG Lift – 2-31
other mast sections. Mast section-5/-6/-7 slide pads
may need to be assembled/disassembled several
times in order to determine the correct shim stock
required for proper fit.
75. Complete the following steps to determine shim
stock thickness required for section-5/-6/-7;
NOTE: Always use the an even amount of shim material
behind slide pads on both sides of the mast rails.
This will keep mast sections centered in rail chan-
nels and prevent any distortion of the section.
a. Use two shim pieces per slide pad, a thick one
and a thin one.
b. Start with a total thickness of approximately
.035" and .075" thick shim stock.
c. Attach shim stock and slide pads to both sides
of mast section-5/-6/-7 using five (5) 1/4"-20UNC
x 1-1/4" long, hex head cap screws per side, with
flatwasher under each bolt head. (Assemble
shim stock and slide pad to mast section rail with
shim stock against rail and slide pad with bev-
eled side out).
PRIOR TO C# 142920 THE AM MAST INSTALLED TWO SHORT
SLIDE PADS ON EACH SIDE OF THE PLATFORM MOUNTING
MAST SECTION. AS OF C# 142920 A LONGER SINGLE PAD IS
INSTALLED ON EACH SIDE.
ON MACHINES PRIOR TO C# 142920 THE 41AM MOUNTS THE
(SHORT) UPPER SLIDE PAD IN THE UPPER SET OF SLIDE PAD
M O U N T I N G H O L E S . T H E 2 0 A M , 2 5 A M , 3 0 A M A N D 3 6 A M
MACHINES MOUNT THE UPPER SLIDE PAD IN THE LOWER SET
OF SLIDE PAD MOUNTING HOLES. (SEE FIGURE 2-5.)
d. Carefully thread the slide pad mounting bolts
with flatwashers through slide pads and shim
stock into threads in mast section-5/-6/-7. Be
certain there are no air gaps between shims,
shim and mast or shim and slide pad when tight-
ened.
NOTE: Mast section-5/-6/-7 into section-4/-5/-6 fit should be
very snug but still be able to be pushed together by
hand. If too tight, remove section-5/-6/-7, disassem-
ble slide pad and reduce thickness of shim stock.
e. Begin sliding top of mast section-5/-6/-7 with
closed rail down engaging the slide pads into
slide pad channels at bottom of mast section-4/-
5/-6’s open rail. Continue to push section-5/-6/-7
into section-4/-5/-6 until BOTTOM ends of mast
sections are even.
f. Check mast section for side play. If play exists
use thicker shims dividing thickness equally
between both sides of mast.
g. When mast slide pads are shimmed properly,
there should be no side to side movement of
slide pad in rail channel. Mast sections should
be very snug in channels but still be able to slide
in channel by hand.
76. Slide mast section-5/-6/-7 to top of section-4/-5/-6.
77. Insert threaded ends of chain assembly (attached to
top of mast section-3/-4/-5) through the chain anchor
plate located on bottom of extended mast section-5/
-6/-7. Loosely thread two (2) 3/8"-16UNC nuts onto
stud threads on each chain. Chains will be adjusted
later in assembly.
78. Slide mast section-5/-6/-7 back into mast section-4/-
5/-6 until bottom ends of masts are even. Check to
make sure chain set attached to top of section-3/-4/-
5 is seating properly in chain sheave wheels
attached to top of mast section-4/-5/-6. (Mast sec-
tions-2, -3, -4 and -5 may need to be restrained to
keep their slide pads from pushing out the bottom of
mast sections-1, -2, -3, -4 and -5).
79. Adjust top and bottom ends of mast sections so they
are all even with each other. At bottom of mast
assembly, thread all chain adjusting nuts on
threaded ends until they are snug against the
anchor plates and all slack is removed from chains.
Check that chains are seated in their sheave wheels
at top of mast assembly.
80. Assemble the latch bar to mast section-5/-6/-7, the
mini covers to the top of each mast section and the
sequencing cables and hardware to the side of the
mast assembly.
Mast assembly should now be complete.
2.10 MAST TO BASE FRAME INSTALLATION
1. Using an overhead crane or suitable lifting device
capable of supporting the weight of base frame,
attach a sling strap or chain to the front crossmem-
ber of the base frame, raise base frame.
2. Extend hydraulic cylinder out from bottom of mast
assembly approximately one (1) foot. (Caps on
extend and return ports will need to be removed to
extend cylinder. Catch any hydraulic fluid expelled
from return port in a container to prevent spillage
onto work area).
3. Bring base frame into position in front of mast
assembly, (base frame and mast assembly must be
held at 90° angle to each other).
4. Slide port end of hydraulic cylinder through hole in
base frame cylinder mounting channel. (Return port
(tube side) of cylinder must be on right side facing
bottom of base and mast).