Lull 944E-42 Service Manual - Manual (Page 499)

8.247 Model 644E-42/944E-42 Rev. 6/04
Hydraulic System
8. Fasten the rod end 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.
9. Remove the two setscrews (8), with locking
inserts (9), from the piston (7). Pry or drill out the
setscrews as required. DO NOT damage the piston
threads. New setscrews, with locking inserts, will be
required for reassembly.
10. Remove the piston (7) from the rod (4).
Note: Loctite Threadlocker #271 (red) and 440-500 lb-ft
(597-678 Nm) were applied to the piston (7) when it was
installed. It may be necessary to apply heat to break the
bond of the sealant between the piston (7) and the
rod (4) before the piston can be unthreaded and
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.
11. Remove the piston square seal (10), square
ring (11) and precision wearband (12) from the
piston (7).
12. From within the piston, remove the small o-ring (13).
13. Remove the locking inserts (14) from their
installation holes in the head gland threads. Pry or
drill out the inserts as required. DO NOT damage the
head gland threads. New locking inserts will be
required for reassembly.
14. Remove the head gland (5) from the rod.
15. Remove the o-ring (15), back-up ring (16) and o-
ring (17) from the head gland (5).
16. From within the head gland (5), remove the precision
wearbands (18) and the deep Z-seal (19) and, from
the other end, remove the square ring (20) and the
rod wiper (21).
c. Swing Carriage Cylinder Cleaning
1. Remove all hydraulic fluid, dirt and debris from the
swing carriage cylinder (1).
2. Discard all seals, back-up rings and o-rings. Replace
with new items from the complete seal kits (22) 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.
4. 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. Swing Carriage Cylinder Inspection
1. Inspect internal surfaces and all parts for wear,
damage, etc. If the inner surface of the tube (6) 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. Clean parts with trichlorethylene after repair.
4. Check that the rod (4) is straight. If it is bent, install a
new rod.
e. Swing Carriage Cylinder Assembly
Note: Follow the information in Section 8.14.3, “General
Cylinder Assembly Instructions.”
1. Install the deep Z-seal (19), orienting the edge (25).
Install the precision wearbands (18) into the forward
end of the head gland (5), and at the rear end, install
the rod wiper (21) and square ring (20). The wiper
lip (24) 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.
2. Install a new oiled o-ring (17), back-up ring (16) and
oiled o-ring (15) onto the head gland (5).
3. Fasten the rod end 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.
4. Push the head gland (5) onto the rod (4). If
necessary, use a soft hammer to drive the head
gland onto the rod.