JLG sky trak mmv Service Manual page 411

Assemble the Extend/Retract Section
1. Assemble the end mechanism (7) by inserting a new
oiled o-ring (8) in the spool cap retainer (9). Install
the flat washer (10), spacer (11), spring (12),
another flat washer (13) and spool end (14) into the
spool cap (15). Install the spool cap retainer (9) onto
the spool cap (15). Place the retainer (16) on the
other end of the spool cap.
2. Insert a new oiled o-ring (17) into the section and
attach the end mechanism (7) with the
capscrews (18).
3. Assemble the other end mechanism (1) by inserting
the spool cap (2) into the retainer (3).
4. Insert a new oiled o-ring (4) onto the extend/retract
section (5) and attach the end mechanism (1) with
the capscrews (6).
5. Install the relief valves (19) with new oiled o-rings
(20) after assembling them using the procedures
that follow.
6. Insert the shuttle (21), poppet (22) and spring (23)
into the section.
7. Place a new oiled o-ring (24) between the extend/
retract section (5) and the lift/lower section (25) and
slide the extend/retract section onto the tie rods (26
& 27).
8. Place a new oiled o-ring (28) between the extend/
retract section (5) and the outlet section (29) and
slide the outlet section onto the tie rods (26 & 27).
9. Torque the two tie rod nuts (30) to 43-53 lb/ft
(58-72 Nm) and the third tie rod nut (31) to
66-82 lb/ft (89-111 Nm) holding all sections together.
Assemble Relief Valves (Extend/Retract Section)
On the extend/retract section (5), one relief valve (19) is
on the "B" side (32) and is preset at 3750 ±50 psi
(258 ±3,5 bar); the other relief valve is on the "A" side (33)
and is preset at 3000 ±50 psi (207 ±3,5 bar).
Note: There is a seal and spring kit for assembling the
relief valves.
For each relief valve (19):
1. Install the poppet (34) and new spring (35) into the
plug (36). Install the adjustment screw (37) and new
oiled o-ring (38) with the nut (39) onto the plug (36).
2. Install the larger poppet (40), smaller poppet (41),
new back-up ring (42), new oiled o-ring (43), poppet
(44) and new small spring (45) into the body (46).
Install the new oiled o-ring (47), new back-up ring
(48) and new large spring (49) into the body (46).
Model MMV Rev. 12/04
3. Install the new oiled o-ring (50) and plug (36) onto
the body (46).
4. Using a wrench on the body (46), install the relief
valve (19) and new oiled o-ring (20) into the extend/
retract section assembly (5).
h. Main Control Valve Installation
1. Place the assembled main control valve (51) into
position on the valve plate assembly (52) aligning
the three bolt holes with the main control valve
holes.
55
53
54
2. Place the plain washers (53) on the capscrews (54).
Insert from the bottom of the valve plate (52).
Note: ALWAYS replace elastic locknuts with new elastic
locknuts to help ensure proper fastening.
3. Tighten the new elastic locknuts (55) onto the
capscrews (54).
Hydraulic System
52
53
51
MM3640
9.113