SkyTrak 8042 Service Manual - Manual (Page 546)

8.131 Model 8042, 10042, 10054 Legacy Rev. 10/03
Hydraulic System
e. Lift/Lower Cylinder Assembly
Note: Follow Section 8.13.3, “General Cylinder Assembly
Instructions.”
1. Install a new small oiled o-ring (11) into the piston
(7).
2. Install the capped T-seal (10) and both precision
wearbands (9) onto the piston (7).
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.
3. Install the precision wearbands (14) into the forward
end of the head gland (6). Install the deep Z-seal
with back-up (15) orienting the edge (20). Install the
sealed, outside diameter heavy-duty rod wiper (17).
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 a new oiled o-ring (12) and back-up ring (13)
onto the head gland (6).
5. Fasten the rear of the rod in a soft-jawed vise, and
put a padded support below and near the threaded
end of the rod to help prevent damage to the rod.
6. Carefully slide the head gland (6) onto the rod (4).
Slide the rod spacer (16) onto the rod.
7. Carefully slide the piston (7) onto the rod (4).
8. Apply Loctite Threadlocker #271 (red) to the threads
of the locknut (8). Thread the locknut onto the rod (4).
Torque to 1750-2000 lb-ft (2373-2712 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 (1).
9. Secure the lift/lower cylinder in a soft-jawed vise or
other acceptable holding equipment if possible.
10. Lubricate the inside of the tube (1) and outside of the
piston (7) and head gland (6) with clean, filtered
hydraulic oil.
11. Apply a compression sleeve or other suitable tool to
the head gland (6) and piston (7) in order to
compress the o-rings, back-up rings and seals, while
inserting the assembled piston, rod and head gland
into the tube (1).
IMPORTANT: When sliding the rod (4) and piston
assembly into the tube, prevent the threaded end of the
tube from damaging the piston (7). Keep the rod
centered within the tube to help prevent binding. Protect
the finish on the rod at all times. Damage to the surface
of the rod can cause seal failure.
12. Carefully insert the rod (4) with all attachments
straight into the tube (1).
13. Using a pin spanner wrench, thread the locking
collar (5) into the tube (1). Torque the locking collar
to 300-400 lb-ft (407-542 Nm).
IMPORTANT: DO NOT tamper with or attempt to reset
the counterbalance valve cartridge (2). If adjustment or
replacement is necessary, replace a counterbalance
valve with a new part.
14. Lubricate the counterbalance valve (2) and the pilot-
operated check valve (3) with clean, filtered
hydraulic oil. Using new oiled o-rings, thread the
valves into tube (1). Torque to 30-35 lb-ft (41-47 Nm).
15. Test the cylinder at low operating pressure (100 psi
or 7 bar). Verify that the piston and the rod move
freely in both directions.
16. Increase the operating pressure to the maximum
amount for the cylinder 3000 psi (207 bar), and
again check for free movement in both directions.
17. Retract the rod fully into the tube, and cap and plug
the hydraulic hose ports.