SkyTrak 8042 Service Manual - Manual (Page 554)

8.139 Model 8042, 10042, 10054 Legacy Rev. 10/03
Hydraulic System
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.
e. Frame Sway Cylinder Assembly
Note: Follow Section 8.13.3, “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 wiper lip seal (19) oriented toward the
rod eyelet. The wiper lip 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 a 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.
11. Apply Loctite Primer “T” and Threadlocker #271
(red), to a new locknut (7) in accordance with Loctite
instructions. Install the nut onto the threaded end of
the rod (6). Torque the nut to 1100-1250 lb-ft (1492-
1695 Nm).
IMPORTANT: Avoid using excess force when clamping
the cylinder in a vise. Apply only enough force to hold the
cylinder securely. Excessive force can damage the
cylinder tube (5).
12. Fasten the tube (5) in a soft-jawed vise or other
suitable holding device.
13. To aid in installation, lubricate the o-rings and the
inside of the tube, piston and head gland with clean,
filtered hydraulic oil.
IMPORTANT: Use a suitable installation tool or
compression sleeve to help prevent twisting or damaging
the seals and o-rings when installing the piston (8) and
head gland (4) into the cylinder. When sliding the rod
and piston assembly into the tube, DO NOT damage the
piston by scraping it against the threads in the tube.
Keep the rod in line with the tube to prevent binding.
14. Keep the rod (6) straight, and carefully insert the rod
into the tube (5). Avoid scratching, nicking or
damaging the tube while installing the rod.
15. Begin threading the head gland (4) into the tube (5).
Place the locking insert (3) in its hole in the head
gland threads, just before the hole is threaded into
the tube. Use a suitable pin spanner wrench to
thread the head gland (4) completely into the tube
(5). Torque the head gland to 300-400 lb-ft (407-542
Nm).
16. Lubricate the pilot-operated check valves (2) with
clean, filtered hydraulic oil. Using new oiled o-rings,
thread the pilot-operated check valves into tube (5).
Torque valves to 35-40 lb-ft (47-54 Nm).
17. Test the cylinder at low operating pressure 100 psi
(6,9 bar) to verify that the piston and rod move freely
in both directions.
18. Increase the operating pressure to the maximum for
the cylinder 3250 psi (224 bar), and check for external
leakage and for free movement in both directions.
19. Retract the piston fully.