JLG 80HX_HX+6_HXER ANSI Service Manual - Manual (Page 104)

SECTION 5 - HYDRAULICS
5-12 – JLG Lift – 3120271
Assembly
NOTE: Prior to cylinder assembly, ensure that the proper
cylinder seal kit is used. See your JLG Parts Manual.
Apply a light film of hydraulic oil to all components
prior to assembly.
IMPORTANT
WHEN INSTALLING ‘POLY-PAK’ PISTON SEALS, ENSURE THE
SEALS ARE INSTALLED PROPERLY. REFER TO FIGURE 2-3 FOR
CORRECT SEAL ORIENTATION. IMPROPER SEAL INSTALLATION
COULD RESULT IN CYLINDER LEAKAGE AND IMPROPER CYLIN-
DER OPERATION.
1. For the telescope cylinder only, support the cylinder
rod and install the assembled rod support on the rod
shaft. Push the support along the rod to the port
block end.
2. Place a new wiper seal and rod seal into the applica-
ble cylinder head gland grooves.
3. Carefully install the head gland on the rod, ensuring
that the wiper and rod seals are not damaged or dis-
lodged. Push the head along the rod to the rod end,
as applicable.
4. Carefully slide the piston spacer on the rod. If appli-
cable, align the oil holes in the rod and the spacer.
Secure the spacer, if applicable.
5. If applicable, correctly place a new o-ring and back-
up rings in the inner piston diameter groove.
6. Carefully place the piston on the cylinder rod, ensur-
ing that the o-ring and back-up rings are not dam-
aged or dislodged.
7. Using suitable protection, clamp the cylinder rod in
a vise or similar holding fixture as close to the piston
as possible.
8. Push the piston onto the rod until it abuts the spacer
end and install the attaching nut.
WHEN REBUILDING THE LIFT, SLAVE LEVEL, TELESCOPE,
STEER, AND EXTEND-A-REACH SLAVE AND LIFT CYLINDERS,
APPLY LOCTITE #242 TO PISTON NUT, THEN TIGHTEN BOTH
SECURELY. (SEE TABLE 5-1 FOR TORQUE SPECIFICATIONS).
NOTE: These cylinders use self-locking knurled cup point
setscrews which should be discarded and replaced
whenever they are removed.
After torquing the piston nut spot drill cylinder rod for
setscrews.
9. If applicable, install the setscrew(s) which secure the
piston attaching nut to the diameter groove. (See
Table 5-1 for Torque Specifications).
10. Remove the cylinder rod from the holding fixture.
11. Place new o-rings and seals in the applicable out-
side diameter grooves of both the piston and the cyl-
inder head.
12. Position the cylinder barrel in a suitable holding fix-
ture.
EXTREME CARE SHOULD BE TAKEN WHEN INSTALLING THE
CYLINDER ROD, HEAD, AND PISTON. AVOID PULLING THE ROD
OFF-CENTER, WHICH COULD CAUSE DAMAGE TO THE PISTON
AND CYLINDER BARREL SURFACES.
13. With barrel clamped securely, and while adequately
supporting the rod, insert the piston end into the
barrel cylinder. Ensure that the piston loading o-ring
and seal ring are not damaged or dislodged.
14. Place the support rods in the tubes provided on the
barrel assembly. The rods will bottom out on the
attached stops. Thread the rods through the rod
support block and, using loctite, tighten the rod nuts
down on the support.
THE SUPPORT RODS MUST BE INSTALLED SO THAT THEY BOT-
TOM OUT SIMULTANEOUSLY ON THE STOPS.
15. Continue pushing the rod into the barrel until the cyl-
inder head gland can be inserted into the barrel cyl-
inder or, if applicable, until the cylinder threads
engage the threads of the barrel.
Figure 5-9. Poly-Pak Seal Installation