Lull 6K Service Manual - Manual (Page 207)

Supply, Pressure, and Return Hydraulics
Service Manual — Models 644B, 6K, 844C, 8K, 1044C, 10K 5-63
5. Remove relief poppet (Item 15) and pilot spring (Item 16) from
adjustment screw.
6. Remove O-ring (Item 17) from adjustment screw.
7. Remove pilot assembly body (Item 14) from relief valve body (Item 4).
8. Remove O-ring (Item 13) from pilot assembly body.
9. Remove spring (Item 12), main poppet (Item 9), filter (Item 8), and
retaining ring (Item 7) from relief valve body.
10. Remove O-ring (Item 11) and backup ring (Item 10) from main poppet.
11. Remove backup ring (Item 6) and O-ring (Item 5) from relief valve
body.
12. Discard all O-rings and backup rings.
13. Clean remaining parts with solvent and dry with compressed air.
Inspect and replace any damaged parts.
Note: Only the O-rings and backup rings can be replaced. If any other parts are
damaged, it will be necessary to replace the entire main relief valve.
Assembly, Main Relief Assembly
(Ref. Fig. 5-39) The following steps are required to reassemble the main relief.
1. Obtain a main relief seal kit. Lubricate each O-ring, backup ring, as
well as other internal parts with hydraulic oil before installing them.
2. Install new O-ring (Item 1) first and then backup ring (Item 2) in cover
assembly.
3. Install new O-ring (Item 5) first and then backup ring (Item 6) in relief
valve body (Item 4).
4. Install backup ring (Item 10) and O-ring (Item 11) on main poppet
(Item 9) as shown in Fig. 5-39.
5. Install retaining ring (Item 7), filter (Item 8), main poppet (Item 9), and
spring (Item 12) in relief valve body.
6. Install O-ring (Item 13) on pilot assembly body (Item 14). The O-ring
must be installed past the second ridge to rest in the recessed area
furthest in.
7. Install the pilot assembly body on the relief valve body. Torque pilot
assembly body to 15–18 ft-lbs.
8. Install new O-ring (Item 17) on adjustment screw (Item 18).
9. Install relief poppet (Item 15) and pilot spring (Item 16) in adjustment
screw and install this assembly in pilot assembly body.
10. Install jam nut (Item 20) on adjustment screw. Torque nut to
15–18 ft-lbs.
11. Install main relief valve on cover assembly. Torque relief valve to
20 ft-lbs.