Lull 6K Service Manual - Manual (Page 516)

Frame Tilt and Oscillation
7-14 Service Manual — Models 644B, 6K, 844C, 8K, 1044C, 10K
Disassembly, Frame Tilt Cylinder
(Ref. Fig. 7-7) The following steps are required to disassemble the frame
tilt cylinder.
1. Mount or support cylinder vertically, with rod end down. Hydraulic oil in
cylinder will drain out during disassembly. Place a suitable pan or tray
under the cylinder.
2. See warning and procedures on page 7-16 for counterbalance valve
(Item 3) removal.
3. Slowly extend and retract cylinder by hand to remove most of the
hydraulic oil.
4. Remove eight (8) capscrews (Item 13) securing head (Item 12) to
barrel (Item 2).
5. Pull rod (Item 11) out to help remove head. Support rod and head
during removal to prevent damage. Do not wiggle rod or head back and
forth to remove; this may damage the components.
6. Remove rod nut (Item 10), piston (Item 9), stroke limiter (Item 8), and
head from rod.
7. Remove two (2) O-ring plugs (Item 4).
8. Remove fittings (Items 6 & 7).
Note: Swivel fittings are not used with the latest production models
(e.g. 644B-37 (S/N 591, 667–) and 644B-42 (S/N 208–)).
9. Using a large, flat bladed screw driver, remove two (2) orifices (Item 5).
10. If the bushings need to be replaced, see “Bushing Replacement”
below.
Cleaning and Inspection, Frame Tilt Cylinder
1. Remove all O-rings, wear rings, and backup rings from cylinder
components and discard.
2. Thoroughly wash components in solvent and dry with compressed air.
3. Inspect inner surface of barrel, outer surface of piston, and length of
the rod for scratches and scoring. If barrel, piston, or rod is damaged, it
must be replaced.
4. Check condition of threads on rod, nut, and capscrews. Replace as
necessary. Do not attempt to repair damaged threads.
Bushing Replacement
1. Fig. 7-7 shows both types of rod end configurations and bushing
locations. Remove pivot bushings (Item 1) using a bushing driver and
hammer or press. Drive one bushing all the way through to remove
other bushing.