SkyTrak 8042 Service Manual - Manual (Page 494)

8.79 Model 8042, 10042, 10054 Legacy Rev. 10/03
Hydraulic System
b. Main Control Valve Disassembly
This section covers disassembly of one half (54) of the
main control valve, including the frame sway (55),
attachment tilt (56), auxiliary hydraulics (57) and load
sense outlet (58) sections of the main control valve.
1. To disassemble the frame sway, attachment tilt,
auxiliary hydraulics and load sense outlet sections of
the main control valve (1), remove the nuts (2 and
52) from the end of the tie rods (3 and 53). Pull the
tie rods out through the sections.
2. Disassemble each section assembly 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 recalibration
or a new relief valve.
Disassemble the Load Sense Outlet Section
1. Carefully separate the load sense outlet section (4) from
the auxiliary hydraulic section (5). Avoid dislodging or
losing the spring (6) and poppet (7) in the auxiliary
hydraulic section.
2. Remove the o-ring (8) from between the two
sections.
3. Remove the shut-off plug (9) and o-ring (10) from the
load sense outlet section (4).
Disassemble the Auxiliary Hydraulic Section
1. Carefully separate the auxiliary hydraulic section (5)
from the attachment tilt section (11). Avoid dislodging
or losing the shuttle (12), spring (13) and poppet (14)
in the attachment tilt section.
2. Remove the o-ring (15) from between the two
sections.
3. Remove the spring (6) and poppet (7) from the
auxiliary hydraulic section (5).
4. Remove the two relief valves (16).
5. Remove the two plugs (17), if installed, and o-rings
(18) from the top of the section.
6. Remove both socket head capscrews (21) securing
the cable retainer assembly (19) to the auxiliary
hydraulic section (5).
7. Remove the retainer (22), both sleeves (23), another
retainer (22), wiper (24) and o-ring (25) from the
cable retainer assembly (19).
8. Remove both socket head capscrews (26) securing
the end mechanism (20) to the auxiliary hydraulic
section (5).
9. Remove the spool cap (27), retainer (22), spool end
(28), spring seat (29), spring (30), another spring
seat (29), wiper (31) and o-ring (32) from the end
mechanism (20).
Disassemble the Relief Valves
Note: If the vehicle includes auxiliary hydraulic, there
will be relief valve assemblies (16) on the auxiliary
hydraulic section. The other relief valve assemblies (33)
are part of the attachment tilt section.
The relief valves are preset at 3250 ±50 psi (224 ±3,5 bar).
1. Remove the relief valve (16 or 33) and o-ring (34) from
the applicable section assembly.
2. Grip the relief valve body (35) with a suitable tool,
and use another tool to remove the nut (36),
revealing an o-ring (37) and the adjustment screw
(38).
3. Carefully remove the plug (39), spring (40) and pilot
poppet (41).
4. Remove the large o-ring (42), back-up ring (43),
small o-ring (44), large spring (45), small spring (46),
piston (47), o-ring (48), back-up ring (49) and relief
valve poppets (50 and 51).
MH3350
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55
56
57
58