SkyTrak 8042 Service Manual - Manual (Page 581)

Hydraulic System
8.166 Model 8042, 10042, 10054 Legacy Rev. 10/03
6. Install a new piston square seal (1), square ring (2).
7. Apply Loctite #242 (blue) to the threads of the piston
(3). Thread the piston (3) onto the rod (4) and torque
to 425-500 ft-lb (576-678 Nm).
8. Apply Loctite #242 (blue) to the threads of the two
setscrews (5). Install two setscrews (5) with nylon
balls (6) into their holes in the piston (3). Tighten
until the nylon balls are deformed into the threads of
the rod.
9. Install the precision wearband (7) onto the piston (3).
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 (8).
10. Place the cylinder tube (8) in a soft-jawed vise or
other acceptable holding equipment if possible.
11. Lubricate the piston (3), head gland (9) and the
inside of the tube (8) with clean, filtered hydraulic oil.
12. Apply a compression sleeve or other suitable tool to
the head gland (9) in order to compress the o-rings
(10 and 11).
IMPORTANT: When sliding the rod and piston assembly
into the tube, prevent the threaded end of the tube from
damaging the piston (3). Keep the rod centered within
the tube to help prevent binding.
13. Carefully insert the rod (4) with all attachments
straight into the tube (8). Apply Loctite #242 (blue) to
the threads of the head gland (9). Use a pin spanner
wrench to thread the head gland into the tube.
Torque the head gland to 300 ±50 lb-ft (407 ±68
Nm).
14. Apply Loctite #242 (blue) to the threads of the lock
screw (12). Thread the lock screw into the flange of
the head gland (9) and torque to 3-4 lb-ft (4-5 Nm).
15. Using new oiled o-rings, install the counterbalance
valve (13) and direct-acting relief valve (14).
Lubricate the cartridge and valve with clean, filtered
hydraulic oil. Torque the valves to 30-35 lb-ft (41-
47 Nm).
16. Test the cylinder at low operating pressure (100 psi
or 7 bar). Verify that the piston and rod move freely
in both directions.
17. Increase the operating pressure to the maximum for
the cylinder (3000 psi or 207 bar). Verify that the
piston and rod move freely in both directions.
18. Retract the piston fully and cap the hydraulic hose
ports. Install the cylinder on the carriage.
19. If the bearing (15) requires replacement, support the
rod (4) in a soft-jawed vise or other suitable holding
device. Carefully press a new bearing into the rod
eyelet.
MH4330
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