JLG 19BD Service Manual - Manual (Page 53)

SECTION 2 - SERVICE PROCEDURES
3121154 – JLG Lift – 2-31
MAST SECTION 4 - ASSEMBLY
44. Locate the remaining mast section-4 (platform
mounting - mast section). Lay mast section on flat
stable surface.
45. Attach the remaining chain bottom anchor plate
(one with threaded holes aligned at the outside of
bracket). Attach through set of holes in bottom of
mast section-3 with four (4) 1/4"-20UNC x 3/4" long
bolts, place a flatwasher under head of each bolt.
NOTE: The platform mounting section slide pads, are
assembled differently than the slide pads for the
other mast sections. Mast section-4 slide pads may
need to be assembled/disassembled several times in
order to determine the correct shim stock required
for proper fit.
46. Complete the following steps to determine shim
stock thickness required for section-4;
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-4 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).
d. Carefully thread the slide pad mounting bolts
with flat washers through slide pads and shim
stock into threads in mast section-4. Be certain
there are no air gaps between shims, shim and
mast or shim and slide pad when tightened.
NOTE: Mast section-4 into section-3 fit should be very snug
but still be able to be pushed together by hand. If too
tight, remove section-4, disassemble slide pad and
reduce thickness of shim stock.
e. Begin sliding top of mast section-4 with closed
rail down engaging the slide pads into slide pad
channels at bottom of mast section-4’s open rail.
Continue to push section-4 into section-3 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.
47. Slide mast section-4 out even with top of section-4.
48. Insert threaded ends of chain assembly (attached to
top of mast section-2) into the opening between
mast section-4 and mast section-4. Slide the
threaded ends through the holes in bottom chain
anchor plate located on bottom of mast section-4.
Loosely thread two (2) 3/8"-16UNC nuts onto stud
threads on each chain. Chains will be adjusted later
in assembly.
49. Slide mast section-4 back into mast section-3 until
bottom ends of masts are even. Check to make sure
chain set attached to top of section-3 is seating
properly in cable sheave wheels attached to top of
mast section-4. (Mast section-3 may need to be
restrained to keep it’s slide pads from pushing out
the bottom of mast sections-2).
50. At bottom of mast assembly, thread all chain adjust-
ing nuts on threaded ends until they are snug
against the bottom anchor plates and all slack is
removed from chains. Check that chains are seated
in their sheave wheels at top of mast assembly.
51. Do not assemble the mini covers to the top of mast
sections until the mast chains have been adjusted
properly.
52. Attach the lanyard attach assembly to the side of
mast section 4.
53. Attach the sequencing cables and hardware to the
sides of the mast assembly.
54. Install the mast chain guard to the top mast section
4.