JLG 740A, Service And Maintenance Manual

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SECTION 5 - HYDRAULICS
5-8 – JLG Lift – 3121160
4. Install washer ring onto rod, carefully install the head
gland on the rod, ensuring that the wiper and rod
seals are not damaged or dislodged. Push the head
along the rod to the rod end, as applicable.
5. Carefully slide the piston spacer on the rod.
NOTE: Upper telescope cylinder piston has an o-ring
installed inside the spacer.
6. If applicable, correctly place a new o-ring and back-
up rings in the inner piston diameter groove.
7. Using suitable protection, clamp the cylinder rod in
a vise or similar holding fixture as close to piston as
possible.
8. Carefully thread the piston on the cylinder rod hand
tight, ensuring that the o-ring and back-up rings are
not damaged or dislodged.
9. Thread piston onto rod until it abuts the spacer end
and install the tapered bushing.
NOTE: When installing the tapered bushing, piston and mat-
ing end of rod must be free of oil.
WHEN REBUILDING THE MASTER, SLAVE, LOWER LIFT, UPPER
LIFT, ARTICULATING FLY BOOM LIFT, UPRIGHT LEVEL, OR
UPPER TELESCOPE CYLINDERS, APPLY LOCTITE #242 TO
TAPERED BUSHING BOLTS, THEN TIGHTEN SECURELY.
10. Install the bolts in tapered bushing using loctite
#242.
11. Remove the cylinder rod from the holding fixture.
12. Place new guide locks and seals in the applicable
outside diameter grooves of the cylinder piston.
(Figure 5-10., Piston Seal Kit Installation)
13. Position the cylinder barrel in a suitable holding fix-
ture.
EXTREME CARE SHOULD BE TAKEN WHEN INSTALLING THE CYLIN-
DER ROD, HEAD, AND PISTON. AVOID PULLING THE ROD OFF-CEN-
TER, WHICH COULD CAUSE DAMAGE TO THE PISTON AND
CYLINDER BARREL SURFACES.
14. 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.
15. Continue pushing the rod into the barrel until the cyl-
inder head gland can be inserted into the barrel cyl-
inder.
Figure 5-9. Installation Of Head Seal Kit
Figure 5-10. Piston Seal Kit Installation
Figure 5-11. Tapered Bushing Installation