Lull 6K Service Manual - Manual (Page 196)

Supply, Pressure, and Return Hydraulics
5-52 Service Manual — Models 644B, 6K, 844C, 8K, 1044C, 10K
1. Loosen and remove four (4) each socket head capscrews (Item 18),
lockwashers (Item 17), and bearing washers (Item 16) that secure
bonnet housing (Item 15) to valve housing (Item 13).
2. Remove bonnet housing. Tag or mark housing; note location of fitting
port(s).
3. Loosen and remove four (4) each socket head capscrews (Item 1),
lockwashers (Item 2) and bearing washers (Item 3) that secure
positioner housing (Item 4) to valve housing.
4. Remove positioner housing. Tag or mark housing; note location of
fitting port(s).
5. Remove spool assembly (Items 5 thru 11).
6. Loosen and remove positioner screw (Item 5) from spool assembly.
CAUTION: A permanent thread locking compound has been applied to
threaded portion of positioner screw. Care must be exercised
to prevent damage to spool during disassembly and cleaning.
Protect the spool while securing it prior to turning positioner
screw and breaking the thread locking compound seal.
7. Remove two (2) flatwashers (Item 6), sleeve stop (Item 7), internal
spring (Item 8), spring (Item 9), and stop collar (Item 10) from spool
(Item 11).
8. Remove two (2) square-cut seals (Items 12 and 14) — one from each
end of valve housing. Discard seals.
9. Clean all parts with solvent and dry with compressed air. Inspect and
replace any damaged parts.
Note: Only the seals, capscrews, lockwashers, and bearing washers can be
purchased individually. If additional items need replacement, it will be
necessary to purchase an assembly that item is a part of. The positioner
assembly includes items 1 thru 10 and 12. The bonnet assembly includes
items 14 thru 18. If the spool (Item 11) becomes damaged, it will be
necessary to purchase a complete new valve section. See parts book for
details.
Assembly, Spool Assembly
The following steps are required to reassemble the spool assembly:
1. Lubricate new square-cut seals with hydraulic oil and install on valve
housing.
2. Install bonnet housing (Item 15) on valve housing with four (4) each
capscrews (Item 18), lockwashers (Item 17), and bearing washers
(Item 16). Refer to note made earlier to ensure housing is installed in
same position as when removed. Torque capscrews to 4–6 ft-lbs.
3. Install stop collar (Item 10), spring (Item 9), internal spring (Item 8),
sleeve stop (Item 7), and two (2) flatwashers (Item 6) on spool
(Item 11).