Lull 944E-42, Service Manual

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Hydraulic System
8.248 Model 644E-42/944E-42 Rev. 6/04
5. Install two new locking inserts (14) into their holes in
the head gland threads.
6. Install a new small oiled o-ring (13) into the
piston (7).
7. Install a new piston square seal (10), square
ring (11) and precision wearband (12) onto the
piston (7).
8. Apply Loctite Primer “T” and Threadlocker #271
(red) to the threads of the piston (7) in accordance
with Loctite instructions. Thread the piston (7) onto
the rod (4) and torque to 440-500 ft/lb (597-678 Nm).
9. Apply Loctite 242 (blue) removable threadlocker to
the threads of the setscrews (8) and install with
locking inserts (9) into their holes in the piston (7).
Torque to 85-95 lb-ft (115-124 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 (6).
10. Place the cylinder tube (6) in a soft-jawed vise or
other acceptable holding equipment if possible.
11. Lubricate the piston (7), head gland (5) and the
inside of the tube (6) with clean, filtered hydraulic oil.
12. Apply a compression sleeve or other suitable tool to
the head gland (5) in order to compress the o-rings
(15 and 16).
IMPORTANT: When sliding the rod and piston assembly
in 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.
13. Carefully insert the rod (4) with all attachments
straight into the tube (6). Use a pin spanner wrench
to thread the head gland into the tube. Torque the
head gland to 250-300 lb-ft (339-407 Nm). Remove
the compression tool.
14. Using all new seals, install the counterbalance valve
(2) and direct-acting relief valve (3). Lubricate the
cartridge and valve with clean, filtered hydraulic oil.
Torque the valves to 35-40 lb-ft (47-54 Nm). Refer to
the Parts Manual for seal kits.
15. Test the cylinder at low operating pressure
(100 psi or 6,9 bar). Verify that the piston and rod
move freely in both directions.
16. 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.
17. Retract the piston fully and cap the hydraulic hose
ports. Install the cylinder on the carriage.
16
MU0020
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