JLG sky trak mmv Service Manual page 460

Hydraulic System
c. Frame Sway Cylinder Internal Cleaning
1. Remove all hydraulic fluid, dirt and debris from the
inner surface of the cylinder.
2. Discard all seals, back-up rings and o-rings. Replace
with new items from a complete seal kit (18) to help
ensure proper cylinder function.
3. Clean all metal parts with an approved cleaning
solvent such as trichlorethylene. Carefully clean
cavities, grooves, threads, etc.
d. Frame Sway Cylinder Inspection and Repair
1. Inspect all parts for wear, damage, etc. If inner
surfaces of the cylinder (1) do not display an ultra-
smooth, polished finish, or are damaged in any way,
replace the damaged part. Often, dirty hydraulic fluid
causes failure of internal seals and damage to the
polished surfaces within the component.
2. Inspect the inside of the tube (5) for scoring and
other damage. If the tube is damaged, replace it with
a new tube.
3. Remove small scratches on the rod or inside of the
tube with very fine grit emery cloth. Use the emery
cloth in a rotary motion to polish out and blend
scratch(es) into the surrounding surface.
4. Clean the parts with trichlorethylene after repair.
5. Check that the rod (6) is straight. If the rod is bent,
install a new rod.
9.162
e. Frame Sway Cylinder Assembly
Note: Follow Section 9.14.3, General Cylinder Assembly
Instructions.
1. Install the deep Z-seal with rod back-up (17) into the
head gland, orienting the edge (20).
2. Install the precision wearband (16) into the head
gland.
3. Install the heavy-duty rod wiper (15) with the raised
portion of the lip seal (19) oriented toward the rod
eyelet. The wiper lip (19) should be toward the outer
end of the head gland and the seal lips toward the
inner end of the head gland. Use tools that will not
damage the seals.
4. Install new oiled o-ring (14), back-up ring (13) and
oiled o-ring (12) onto the head gland (4). If the back-
up ring is not flat on both sides, the side with the arc
must be toward the o-ring.
5. Install the head gland (4) onto the rod (6). If
necessary, use a soft hammer to drive the head
gland onto the rod.
6. Install the new small oiled o-ring (9) into the
piston (8).
7. Install the capped T-seal (11) onto the piston (8).
Note: The T-seal actually consists of four components; a
wide, flexible inner band, the flexible T-seal band itself,
and two supportive split caps that mount on either side of
the "T" seal band.
8. Install the two precision wearbands (10) onto the
piston (8).
9. Install the piston (8) onto the rod (6).
10. Secure the rod eyelet in a soft-jawed vise or other
suitable holding device. Place a padded support
below the threaded end of the rod to help prevent
damaging the rod.
Model MMV Rev. 12/04