JLG 20VP (3120728) Service Manual - Manual (Page 52)

SECTION 2 - SERVICE PROCEDURES
2-34 – JLG Lift – 3120728
e. Holding complete cable sheave wheel assem-
bly, slide assembly into top of mast section-4
and align threaded holes in sheave pin attach
bars with holes in mast rails.
f. Attach to top of mast section-4 using two (2) 3/
8"-16UNC x 1/2" long socket head-countersunk-
flathead cap screws, each side. Coat threads
with Loctite #171 and tighten.
NOTE: When sliding mast sections together, be careful not
to scratch or score the anodized finish in the slide
pad channels.
39. Carefully slide mast section-4 back into section-3
until ends are even. Check to make sure cable/chain
assemblies are seating properly in cable/chain
sheave wheels attached to top of mast section-3.
NOTE: Do not attach mast slide pads and shims to mast
sections before assembling sections. If assembled in
this manner, due to the tight fit of the slide pads in
the slide pad rails, the anodized finish could be
removed from the receiving mast’s slide pad chan-
nels.
40. Insert slide pads into the top end mast rails between
section-3 and -4, (one on each side of the mast),
with beveled surface facing inward towards section-
4.
41. Thread slide pad attaching bolts, (two (2) 1/4"-
20UNC x 3/8" long hex head bolts, place a flat
washer under head of each bolt), through holes in
outside rail, on top of mast section-3 and into the
slide pad inserts. Thread in enough to hold pad in
place.
42. Shim per instructions in step 7.
43. Insert slide pads into the bottom end mast rails
between section-3 and -4, (one on each side of the
mast), with beveled surface facing out towards sec-
tion-3.
44. Thread slide pad attaching bolts, (two (2) 1/4"-
20UNC x 3/8" long hex head bolts, place a flat
washer under head of each bolt), through holes on
inside rail, on bottom end of mast section-4 and into
the slide pad inserts. Thread in enough to hold pad
in place.
45. Shim per instructions in step 7.
NOTE: The platform mounting section (section—4 on 15VP
and section-5 20VP machines) slide pads, are
assembled differently than the slide pads for the
other mast sections. Mast section-4/-5 slide pads
may need to be assembled/disassembled several
times in order to determine the correct shim stock
required for proper fit.
46. Locate the remaining mast section-4/-5 (platform
mounting- mast section). Lay mast section on flat
stable surface.
47. Attach the remaining chain/cable anchor plate (one
with threaded holes vertically aligned in center of
bracket). Attach through inner (vertical) set of holes
in bottom of mast section-4/-5 with two (2) 1/4"-
20UNC x 3/4" long bolts, place a flatwasher under
head of each bolt.
48. Complete the following steps to determine shim
stock thickness required for section-4/-5;
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.
NOTE: To protect the anodized finish when sliding the
assembled mast section-4/-5 into section-3/-4, grind
top and bottom edges of slide pads to approximately
a 1/4" radius.
c. Attach shim stock and slide pads to both sides
of mast section-4/-5 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 flatwashers through slide pads and shim
stock into threads in mast section-4/-5. Be cer-
tain there are no air gaps between shims, shim
and mast or shim and slide pad when tightened.
NOTE: When sliding mast section-4/-5 into section-3/-4 note
amount of force required to push sections together.
Fit should be very snug but still be able to be pushed
together by hand. If too tight, remove section-4/-5,
disassemble slide pad from section-4/-5 and reduce
thickness of shim stock. Open rails of section-3/-4
may be sprayed with silicone spray to help section-4/
-5 slide easier.
e. Begin sliding top of mast section-4/-5 with
closed rail down engaging the slide pads into
slide pad channels at bottom of mast section-3/-
4’s open rail. Continue to push section-4/-5 into
section-3/-4 until BOTTOM ends of mast sec-
tions are even.
f. Check mast section for side play. If play exists
use thicker shims dividing thickness equally
between both sides of mast.