JLG sky trak mmv Service Manual page 403

c. Main Control Valve Disassembly
This section covers the disassembly of the other half (1)
of the main control valve, including the outlet (2),
extend/retract (3), lift/lower (4) and mid-inlet (5) sections
of the main control valve.
1. To disassemble the outlet, extend/retract, lift/lower
and mid-inlet sections of the main control valve (1),
remove the three nuts (6 and 7) from the end of the
tie rods (8 and 9). The tie rods can remain in place in
the sections.
2. Disassemble each section as required.
Some sections include a pre-adjusted relief valve that
regulates pressure in a specific circuit.
IMPORTANT: DO NOT adjust any of the relief valve
assemblies! Tampering with a relief valve will irrevocably
alter pressure in the affected circuit, requiring re-calibration
or a new relief valve assembly.
Disassemble the Extend/Retract and Lift/Lower Outlet
Section
1. Carefully separate the outlet section (2) from the
extend/retract section (3). Avoid dislodging or losing
the shuttle (10), spring (11) and poppet (12).
2. Remove the o-ring (13) from between the two
sections.
3. Remove the shut-off plug (14) and o-ring (15) from
the outlet section (2).
4. Remove the plug (16), o-ring (17), plug (18),
o-ring (19), plug (20), o-ring (21), plug (22) and
o-ring (23) from the outlet section (2).
Model MMV Rev. 12/04
Disassemble the Main Relief Valve (Outlet Section)
Note: The internal parts of the relief valve can be disas-
sembled without removing the relief valve body ( 24 ) from
the outlet section. Skip to step 2 to start disassembly of
the relief valve.
The main relief valve (24) is part of the outlet section (2).
The valve is preset at 3000 ±100 psi (207 ±6,9 bar).
1. Remove the relief valve (24) and the seal (25) from
the outlet section (2).
2. Grip the relief valve body (26) with a suitable tool
and use another tool to remove the nut (27),
revealing an o-ring (28) and the adjustment
screw (29).
3. Remove the nut (30), o-ring (31), shim (32),
spring (33), spring retainer (34), and poppet (35).
4. Remove the plug (36) from the body (26).
Disassemble the Extend/Retract Section
1. Carefully separate the extend/retract section (3) from
the lift/lower section (4). Avoid dislodging or losing
the shuttle (37), spring (38) and poppet (39).
2. Remove the o-ring (40) from between the two
sections.
3. Remove the shuttle (10), spring (11) and poppet (12)
from the extend/retract section (3).
4. Remove the two socket head capscrews (41)
securing the end mechanism (42) to the extend/
retract section (3).
5. Remove the retainer (43), spool cap (44) and o-ring
(45) from the end mechanism (42).
6. Remove both socket head capscrews (46) securing
the other end mechanism (47) to the extend/retract
section (3).
7. Remove the retainer (48). Remove the spool cap
(49) by unthreading it from the spool cap retainer
(56).
8. Hold the spool from turning while removing the spool
end (50) from the spool.
9. Remove the flat washer (51), spring (52), spacer
(53), another flat washer (54), o-ring (55), spool cap
retainer (56) and o-ring (57) from this end
mechanism (47).
Hydraulic System
9.105