SkyTrak 8042 Service Manual - Manual (Page 498)

8.83 Model 8042, 10042, 10054 Legacy Rev. 10/03
Hydraulic System
1. To disassemble the outlet, lift/lower, extend/retract
and mid-inlet/outlet sections of the main control
valve (1), remove the three nuts (2 and 3) from the
end of the three tie rods (4 and 5). Pull the tie rods
out through the section assemblies.
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 recalibration
or a new relief valve assembly.
Disassemble the Outlet Section
1. Carefully separate the outlet section (6) from the lift/
lower section (26). Avoid dislodging or losing the
shuttle (27), spring (28) and poppet (29) in the lift/
lower section.
2. Remove the o-ring (7) from between the two
sections.
3. Remove the plugs (8 and 9) and o-rings (10 and 11)
from the outlet section (6).
Disassemble the Relief Valves (Outlet Section)
The load sense relief valve (12) and the main relief valve
(13) are part of the outlet section (6). The load sense
relief valve is preset at 2600 psi (179 bar). The main relief
valve is preset at 3500 psi (241 bar).
1. Remove the load sense relief valve (12) from the
outlet section (6).
2. Remove the o-ring (54) from the relief valve.
3. Grip the relief valve body (55) with a suitable tool,
and use another tool to remove the nut (56),
revealing an o-ring (57) and the adjustment screw
(58).
4. Remove the nut (59), o-ring (60), shim (61), spring
(62), spring retainer (63) and poppet (64).
5. Remove the plug (65) from the body (55).
6. Remove the main relief valve (13) from the outlet
section (6).
7. Remove the o-ring (14) from the relief valve.
8. Grip the relief valve body (15) with a suitable tool, and
use another tool to remove the nut (16), revealing an o-
ring (17) and the adjustment screw (18).
9. Remove the nut (19), o-ring (20), shim (21), spring
(22), spring retainer (23), and poppet (24).
10. Remove the plug (25) from the body (15).
Disassemble the Lift/Lower Section
1. Carefully separate the lift/lower section (26) from the
extend/retract section (30). Avoid dislodging or
losing the shuttle (31), spring (32) and poppet (33) in
the extend/retract section.
2. Remove the o-ring (34) from between the two
sections. Remove the shuttle (27), spring (28) and
poppet (29) from the lift/lower section (26).
3. Remove the anti-void assembly (35) from the lift/
lower section (26).
4. Remove the relief valve (36). Refer to “Disassemble
the Relief Valve (Lift/Lower and Extend/Retract
Sections)” on page 8.85.
5. Remove both socket head capscrews (37) securing
the cable retainer assembly (38) to the lift/lower
section (26).
6. Remove the retainer (39), both sleeves (40), another
retainer (39), wiper (41) and o-ring (42) from the
cable retainer assembly (38).
7. Remove both socket head capscrews (43) securing
the end mechanism (44) to the lift/lower section (26).
8. Remove the spool cap (45), retainer (39), spool end
(46), spring seat (47), spring (48), another spring seat
(49), wiper (50) and o-ring (51) from the end mechanism
(44).
Disassemble the Extend/Retract Section
1. Carefully separate the extend/retract section (30)
from the mid-inlet/outlet section (52). Avoid
dislodging or losing the shuttle (66) from the mid-
inlet/outlet section.
2. Remove the o-ring (53) from between the two
sections.
3. Remove the shuttle (31), spring (32) and poppet (33)
from the extend/retract section (30).
4. Remove the two socket head capscrews (37)
securing the cable retainer assembly (38) to the
extend/retract section (30).
5. Remove the retainer (39), both sleeves (40), another
retainer (39), wiper (41) and o-ring (42) from the
cable retainer assembly (38).
6. Remove both socket head capscrews (43) securing
the end mechanism (44) to the extend/retract section
(30).
7. Remove the spool cap (45), retainer (39), spool end
(46), spring seat (47), spring (48), another spring
seat (49), wiper (50) and o-ring (51) from the end
mechanism (44).