SkyTrak 8042 Service Manual - Manual (Page 548)

8.133 Model 8042, 10042, 10054 Legacy Rev. 10/03
Hydraulic System
9. Remove the two setscrews (9) from the locknut (10).
Under each setscrew is a nylon ball (11). Be sure to
remove the nylon balls from the locknut. Discard the
nylon balls.
10. Remove the locknut (10) from the rod (5). The
locknut is torqued at 1735-1885 lb-ft (2352-2556
Nm).
Note: It may be necessary to apply heat to break the
bond of the sealant between the locknut (10) and the rod
(5) before the piston (8) can be removed. Some parts of
cylinders are sealed with a special organic sealant and
locking compound.
Before attempting to disassemble these parts, remove
any accessible seals from the area of the bonded joint.
Wipe off any hydraulic oil and heat the joint uniformly to
break the bond. A temperature of 300-400° F (149-204° C)
will destroy the bond. Avoid overheating or the parts may
become distorted or damaged. Apply sufficient torque or
pressure for removal while the parts are still hot.
Breakdown of sealant will leave a white, powdery
residue on threads and parts. Clean the residue away
with a soft brass wire brush prior to reassembly, and
wipe with Loctite “T” cleaner before reinstallation.
11. Remove the piston (8) from the rod (5).
12. Remove the precision wearband (12) and the
capped T-seal (13) from 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” itself.
13. Remove the small o-ring (14) from the end of the rod
(5).
14. Remove the o-ring (15) and back-up ring (16) from
the head gland (7).
15. Remove the precision wearbands (17) from within
the head gland (7). Remove the sealed, outside
diameter heavy-duty rod wiper (18) and the deep Z-
seal with back-up (19) from the other end of the
head gland. Remove the rod spacer (20).
c. Lift/Lower Cylinder Cleaning
1. Remove all hydraulic fluid, dirt and debris from the
inner surface of the cylinder tube (2).
2. Discard all seals, back-up rings, o-rings, etc.
Replace with new items from a complete seal kit (21)
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.
Note: If a white, powdery residue is present on threads
and parts, it can be removed. Clean the residue away
with a soft brass wire brush prior to reassembly, and
wipe with Loctite “T” cleaner before reinstallation.
d. Lift/Lower Cylinder Inspection
1. Inspect internal surfaces and all parts for wear,
damage, etc. If inner surface of the tube (2) does not
display a smooth finish, or is scored or damaged in
any way, replace the tube. Often, dirty hydraulic fluid
causes failure of internal seals and damage to the
smooth surface within the tube.
2. Remove slight scratches on the piston, rod or inner
surface of the tube with very fine grit emery cloth.
Use the emery cloth in a rotary motion to polish out
and blend the scratch(es) into the surrounding
surface.
3. Clean parts with trichlorethylene.
4. Check that the rod (5) is straight. If it is bent, install a
new rod.