Lull 944E-42 Service Manual Download

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8.215

Model 644E-42/944E-42

Rev. 6/04

Hydraulic System

9. Remove the locknut (8) from the rod (4). The locknut

is a deformed-thread type nut torqued at 1100-1250
lb-ft (1491-1695 Nm).

Note: It may be necessary to apply heat to break the
bond of the sealant between the locknut (8) and the
rod (4) before the piston (7) can be removed. Some
parts of cylinders are sealed with a special organic
sealant and locking compound.

Before attempting to disassemble these parts, remove
any accessible seals from the area of the bonded joint.
Wipe off any hydraulic oil and heat the joint uniformly to
break the bond. A temperature of 300-400° F (149-204° C)
will destroy the bond. Avoid overheating or the parts may
become distorted or damaged. Apply sufficient torque or
pressure for removal while the parts are still hot.

Breakdown of sealant will leave a white, powdery residue
on threads and parts. Clean the residue away with a soft
brass wire brush prior to reassembly, and wipe with
Loctite “T” cleaner before reinstallation.

10. Remove the piston (7) and head gland (6) from the

rod (4).

11. Remove the o-ring (9), back-up ring (10), and o-ring

(11) from the head gland (6).

12. Remove the locking insert (12) from its hole in the

head gland threads. Pry or drill out the insert as
required. DO NOT damage the head gland threads.
A new locking insert will be required for reassembly.

13. Remove the precision wearband (13) and the deep

Z-seal with rod back-up (14) from the front of the
head gland (6). Remove the sealed outside diameter
heavy-duty rod wiper (15) from the rear of the head
gland.

14. Remove both precision wearbands (16) and the

capped T-seal (17) from 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.

15. Remove the small o-ring (18) from within the

piston (7).

16. If the bushings (19) need replacement, support the

rod (4) in a soft-jawed vise or other suitable holding
device. Carefully press the bushings from the rod.

17. Remove the grease fitting (20) from the base end of

the cylinder tube.

c. Attachment Tilt Cylinder Cleaning

1. Thoroughly clean the inner surface of the attachment

tilt cylinder with trichlorethylene or another approved
cleaner.

2. Discard all seals, back-up rings and o-rings. Replace

with new items from a complete seal kit (21) to help
ensure proper cylinder function.

3. Clean all metal parts with an approved cleaning

solvent such as trichlorethylene. Carefully clean
cavities, grooves, threads, etc.

Note: If a white, powdery residue is present on threads
and parts, it can be removed. Clean the residue away
with a soft brass wire brush prior to reassembly, and
wipe with Loctite “T” cleaner before reinstallation.

d. Attachment Tilt Cylinder Inspection

1. Inspect internal surfaces and all parts for wear,

damage, etc. If the inner surface of the tube (2) does
not display a smooth finish, or is scored or damaged
in any way, replace the tube. Often, dirty hydraulic
fluid causes failure of internal seals and damage to
the smooth surface within the tube.

2. Remove slight scratches on the piston, rod, or inner

surface of the tube with very fine grit emery cloth.
Use the emery cloth in a rotary motion to polish out
and blend the scratch(es) into the surrounding
surface.

3. Inspect all other components for wear, damage, etc.

Clean parts with trichlorethylene.

4. Check that the rod (4) is straight. If it is bent, a new

rod must be installed.

e. Attachment Tilt Cylinder Assembly

Note: Follow Section 8.14.3, “General Cylinder
Assembly Instructions.”

1. Install the sealed outside diameter heavy-duty rod

wiper (15) into the outer end of the head gland (6).
The wiper lip (22) 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.

Lull 944E-42, Service Manual

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