Lull 944E-42 Service Manual - Manual (Page 481)

8.229 Model 644E-42/944E-42 Rev. 6/04
Hydraulic System
8. Apply Loctite Threadlocker #271 (red) to the threads
of the rod (8). Thread the locknut (13) onto the rod
(8). Torque to 2200-2600 lb-ft (2983-3525 Nm).
9. Install two new locking inserts (12) into the holes in
the head gland threads.
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 (2).
10. Secure the lift/lower cylinder (1) in a soft-jawed vise
or other acceptable holding equipment if possible.
11. Lubricate the inside of the tube (2) and outside of the
piston (11) and head gland (10) with clean, filtered
hydraulic oil.
12. Apply a compression sleeve or other suitable tool to
the head gland (10) and piston (11) in order to
compress the o-rings, back-up rings and seals while
inserting the assembled piston, rod and head into
the tube (2).
IMPORTANT: When sliding the rod (8) and piston
assembly in the tube, prevent the threaded end of the
tube from damaging the piston (11). 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.
13. Carefully insert the rod (8), with all attachments,
straight into the tube (2).
14. Using a pin spanner wrench, thread the head gland
(10) into the tube (2). Torque the head gland to 500-
600 lb-ft (678-814 Nm).
IMPORTANT: DO NOT tamper with or attempt to reset
the counterbalance valve cartridge (3). If adjustment or
replacement is necessary, replace a counterbalance
valve with a new part.
15. Lubricate the counterbalance valve (3) and the pilot-
operated check valve (4) with clean, filtered
hydraulic oil. Using all new seals, thread the valves
into tube (2). Torque to 45-50 lb-ft (61-68 Nm). Refer
to the Parts Manual for seal kits.
16. Reassemble the two hex plugs (23) into the ports in
the base end of the cylinder. Torque the plug to 10-
12 lb-ft (14-16 Nm).
17. If the self-aligning bearings (6 and 9) require
replacement, support the rod (8) in a soft-jawed vise
or other suitable holding device. Carefully press new
bearings into the tube or rod eyelet. When installing
the bearings, the fracture in the bearing race must
be positioned perpendicular (27) to the force of the
load.
18. If necessary, install grease fittings (5 and 7) into the
tapped holes in the end of the tube and rod eyelets.
Lubricate the spherical bearing (9) in the rod end
through the grease fitting (7) with multi-purpose
grease before the boom is operated. Lubricate the
spherical bearing (6) in the tube end through the
grease fitting (5) with multi-purpose grease before
the boom is operated.
19. Test the cylinder at low operating pressure
(100 psi or 6,9 bar). Verify that the piston and the rod
move freely in both directions.
20. Increase the operating pressure to the maximum
amount for the cylinder (4000 psi or 276 bar) and
again check for free movement in both directions.
21. Retract the rod fully into the tube and cap and plug
the hydraulic hose ports.
f. Lift/Lower Cylinder Installation
1. Reassemble the cylinder to the boom and transfer
carriage. Refer to Section 3.3.3, “Outer Boom
Replacement,” and Section 11.3.2, “Transfer
Carriage Installation,” to install the lift/lower cylinder.
2. Refer to the fastener torque chart in Section 2.3,
“Torques.”
3. Connect all hoses according to the labels or other
marks used to identify their location during removal.
4. Operate the vehicle to check all boom functions and
for hydraulic system leaks.
5. Wipe up any hydraulic fluid spillage in, on, near and
around the vehicle. Perform the pressure check and
circuit bleeding procedure that follows.
WARNING:
DO NOT get under a raised
boom unless the boom is blocked up. Always
block the boom before doing any servicing that
requires the boom to be up. Unexpected
lowering of the boom may cause death or
serious injury.
WARNING:
Escaping hydraulic fluid
under pressure can penetrate the skin, causing
death or serious injury.
MU4620
27
27