Two-Stage Mast 4000 SRM 764
Legend for Figure 4
A. POSITION 1 B. POSITION 2 C. REAR VIEW HOSE
ROUTING
-LIFT
1. ELEVATING MAST
WELDMENT
2. STATIONARY MAST
WELDMENT
3. MAIN LIFT CYLI
NDER
A. LOCK PLATE
B. RETAINER
4. CHAIN ANCHOR
5. CHAIN SHEAVE ASSEMBLY
(RH)
A. CHAIN SHEAVE
B. BALL BEARING
C. SNAP RING
6. MAIN LIFT CHAIN
7. LOAD ROLLER
8. FLOW REGULATOR HOUSING
9. HYDRAULIC TUB
E(MAIN
LIFT)
10. HYDRAULIC HOSE (MAIN
LIFT)
11. TRUNNION STUB SHAFT
12. TO TRUCK CONTROL VALVE
2. Remove the sna
p rings and washers from the
topofeachlif
t cylinder. Use a pry bar to move
the inner mast
weldment approximately 152 to
305 mm (6 to 12
in.) out from the top of the
outer mast we
ldment. Remove the chain and
hose sheaves
.
3. Installasli
ng near the center of each channel of
the inner ma
st weldment so it will be balanced.
The slings m
ust pass through the loop at the end
of the sling
so the sling tightens and does not slip
on the chann
el as the weldment is lifted. Fasten
a crane to th
eslings.
4. Use the cran
etomovetheinnermastweldment
out of the o
uter mast weldment. Move the mast
weldment u
ntil the bottom rollers of the inner
mast weldm
ent touch the top rollers of the outer
mast weldm
ent. Use the crane to raise the top
of the inne
rmastweldmentsoitisatanangle
of approxi
mately 30°. Lift the weldment straight
up to remo
ve the inner from the outer mast weld-
ment. Put
the weldment flat on the floor so it
cannot fa
ll.
5. Clean the
area at the hydraulic fittings for the
lift cyli
nders. Disconnect the fittings. Put caps
on the op
en fittings and cylinder port to prevent
dirt fro
m entering the system. Remove the snap
rings at
the bottom of each cylinder.
6. Install
a sling near the center of the lift cylin-
der in th
esamemannerusedforthemastweld-
ment rem
oval. Remove the capscrew, washer,
and spac
er that fastens the cylinder to the outer
mast ch
annel. See Figure 3. Use the crane to
move th
ecylinderfromthebaseholeandremove
the cyl
inder from the mast. Repeat the procedure
to remo
ve the other cylinder.
7. Remove the sna
p rings from the lower and upper
load rollers.
Make a note of the shim arrange-
ment as each lo
ad roller is removed. The shim ar-
rangement wi
ll be approximately the same when
the mast is as
sembled.
8. Remove the st
rip bearings from the outer mast
weldment. Ma
ke a note of the shim arrangement
during remo
val of the strip bearings for correct
installati
on during assembly.
9. Disassembl
e the sheaves and rollers as necessary
forrepaira
nd cleaning.
CLEAN AND IN
SPECT
NOTE: These
cleaning and inspection procedures ap-
ply to both t
he two-stage and three-stage masts.
CAUTION
Do NOT use steam to clean the lift chains,
sheaves, or load rollers. The sheaves and
roller bearings are sealed and permanently
lubricated. Do not use compressed air on the
bearings. The air can force the lubricant out
of the bearings. Follow the manufacturer’s
instructions when using solvent.
1. Wash the lift chains with solvent. Use com-
pressed air to dry the chains. Inspect the chains
forwearanddamage.
2. Inspect the lift chains for cracks or broken links
and pins. Check for corrosion or worn holes in the
links. When the pins or the holes wear, the chain
becomes longer. The chain links that run over the
chain sheaves have the most wear. If a chain is 3
percent longer than a new chain, the chain must
be replaced. If a chain scale is available, check
the lift chains as shown in Figure 5. If a chain
scale is not available, measure 20 links of chain.
Replace the chains if the increase in length is 3
percent or greater.
8
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