Lull 6K Service Manual - Manual (Page 285)

Boom and Transfer
Service Manual — Models 644B, 6K, 844C, 8K, 1044C, 10K 6-35
(Ref. Fig. 6-21) The following procedure describes disassembly and
overhaul of the boom hydraulic control valve assembly.
1. Loosen and remove three (3) hex nuts (Items 14 and 15).
2. Remove three (3) tie rods (Items 3 and 4) with remaining three (3) hex
nuts (Items 1 and 2).
3. Separate the four (4) sections — outlet housing (Item 5), two (2) spool
housings (Item 9) and inlet housing (Item 12).
4. Remove the two (2) each springs (Item 7) and poppets (Item 8).
5. Remove the three (3) O-rings (Item 6) between sections and discard.
6. Remove the plug (Item 10) and O-ring (Item 11) from the inlet section
housing (Item 12). Discard the O-ring.
7. Remove the relief valve assembly (Item 13) and set aside for further
disassembly.
8. Clean all remaining parts with solvent and dry with compressed air.
Inspect and replace any damaged parts.
9. Lubricate new O-ring (Item 11) and install it on plug (Item 10) Install
plug on inlet section housing (Item 12). Torque plug to 85–95 ft-lbs.
10. Lubricate three (3) new O-rings (Item 6) and install them on the two (2)
spool housings (Item 9) and inlet section housing (Item 12).
11. Install three (3) tie rods (Items 3 and 4) with hex nuts (Items 1 and 2) in
the outlet section housing.
12. Install spring (Item 7) and poppet (Item 8) in each spool housing before
installing them on the tie rods.
13. Install inlet section housing (Item 12) on tie rods.
14. Install the remaining three (3) hex nuts (Items 14 and 15) onto the ends
of the tie rods. Torque smaller two nuts (Item 15) to 48 ft-lbs and the
larger nut (Item 14) to 74 ft-lbs.
Boom Control Valve Reassembly
(Ref. Fig. 6-20) The following procedure describes reassembly of the
boom control valve. All steps will need to be completed for both valves.
1. Install the spool cap (Item 15), retainer (Item 16), and the two (2)
socket head capscrews (Item 17) onto the spool housing (Item 13). For
final tightening of the capscrews, torque to 50 in-lbs.
2. Install the spool assembly (Items 3 thru 12) into the spool housing
(Item 13).
3. Install the retainer (Item 2) and two (2) socket head capscrews (Item 1)
onto the spool housing. For final tightening of the capscrews, torque to
50 in-lbs.
4. Disassemble relief valve assembly as described below.