Lull 6K Service Manual User Manual
Page 338
Boom and Transfer
6-88
Service Manual — Models 644B, 6K, 844C, 8K, 1044C, 10K
2. Mount or support the cylinder vertically with the rod end down.
Hydraulic oil in cylinder will drain out during disassembly. Place a
suitable pan or tray under the cylinder.
3. Release pressure in the cylinder as follows:
WARNING: Counterbalance valve cartridges trap hydraulic pressure in the
cylinder. Wear proper eye and hand protection when removing
counterbalance valve cartridges. Hydraulic fluid under
pressure can be injected under skin or into eyes, resulting in
serious personal injury or death.
a. Place socket wrench over each counterbalance valve cartridge
(Items 14 and 16). Wrap a clean shop rag around the socket to
cover the area of the counterbalance valve cartridge.
b. Carefully and slowly, turn the cartridge out of the manifold block to
release pressure in cylinder.
4. Remove the counterbalance valve cartridges.
5. Slowly extend and retract the cylinder by hand to remove most of the
hydraulic oil.
6. Remove the setscrew (Item 18) between the cylinder barrel and the
rod bearing head (Item 26).
7. Using the three (3) holes in the side of the rod bearing head, install a
spanner wrench and remove the head.
8. Remove the cylinder rod assembly from the cylinder barrel.
CAUTION: To prevent possible damage to components, support the
cylinder rod assembly; do not wiggle the rod or head back and
forth during removal.
9. Remove the rod nut (Item 21), piston (Item 24), stroke limiter(s)
(Item 25), and rod bearing head from the cylinder rod (Item 27).
Note: Models 644B-37 (S/N 258–) and 6K-37 (S/N 170–) have only one stroke
limiter.
10. Remove two (2) O-ring plugs (Item 13) from the cylinder manifold
block.
11. Remove all O-rings, wear rings, and backup rings from the cylinder
components; discard the rings.
12. Thoroughly clean all components with solvent and dry with
compressed air. Inspect and replace if damaged.
13. Inspect the inner surface of the barrel, the outer surface of the piston,
and the length of rod for scratches and scoring. If the barrel, piston, or
rod is damaged, it must be replaced.
14. Check condition of the threads on the rod, nut, and capscrews. Do not
attempt to repair damaged threads.