Lull 6K Service Manual - Manual (Page 287)

Boom and Transfer
Service Manual — Models 644B, 6K, 844C, 8K, 1044C, 10K 6-37
7. Remove piston (Item 7) and poppet (Item 4) from poppet (Item 3).
8. Remove O-ring (Item 1) from valve body (Item 2), the backup ring
(Item 5) and O-ring (Item 6) from the poppet (Item 4), and the two
O-rings (Items 9 and 11) and backup ring (Item 10) from the plug
(Item 12).
9. Discard all O-rings, backup rings, and springs.
10. Clean all remaining parts with solvent and dry with compressed air.
Inspect and replace any damaged parts.
Note: Only two poppets (Items 4 and 13) and the two nuts (Items 17 and 19) can
be purchased individually. Damage to the other parts (Items 2, 3, 7, 12, and
15) will require replacement of the entire relief valve assembly.
11. Obtain new O-rings, backup rings, and springs from seal and spring
kit. Lubricate each O-ring before installing it.
12. Install large O-ring (Item 11) on plug (Item 12) near the hex head.
Install the backup ring (Item 10) and O-ring (Item 9) on the end of the
plug in order shown in Fig. 6-22.
13. Install spring (Item 8) into plug (Item 12).
14. Insert the poppet (Item 13), spring (Item 14), and adjusting screw
(Item 15) into the end of the plug (Item 12).
Note: Refer to notes made during disassemble and tighten the adjusting screw
the same number of turns as when removed.
15. Install backup ring (Item 5) and O-ring (Item 6) on poppet (Item 4) in
order shown in Fig. 6-22.
16. Installed poppet (Item 4) and piston (Item 7) into poppet (Item 3) and
install this assembly into the valve body (Item 2).
17. Reconnect the valve body (Item 2) to the plug (Item 12). Torque the
plug to 43–53 ft-lbs.
18. Install O-ring (Item 1) on valve body (Item 2).
19. Insert O-ring (Item 16) into the hex nut (Item 17) and install it on the
adjusting screw. Torque to 205–235 in-lbs while making sure that
adjusting screw position does not change.
20. Insert the O-ring (Item 18) into the rounded end nut (Item 19) and
install it on the adjusting screw. Torque to 205–235 in-lbs.
21. Install the assembled relief valve (Fig. 6-21, Item 13) on the inlet
section housing (Fig. 6-21, Item 12). Torque valve body (Item 2) to 33
ft-lbs.
22. Perform a pressure test of the relief valve
Fitting Installation and Pressure Check
(Ref. Fig. 6-19) The following steps are required to install fittings on the
boom control valve.