JLG 4394RT Service Manual - Manual (Page 172)

SECTION 4 - HYDRAULICS
4-6 – JLG Lift – 3121249
3. Place a new “o”ring and back-up seal in the applica-
ble outside diameter groove of the cylinder head.
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.
6. If applicable, correctly place new o-ring in the inner
piston diameter groove. (The backup ring side fac-
ing the O-ring is grooved.)
7. If applicable, correctly place new seals and guide
lock rings in the outer piston diameter groove. (A
tube, with I.D. slightly larger than the O.D. of the pis-
ton is recommended to install the solid seal.)
NOTE: The backup rings for the solid seal have a radius on
one side. This side faces the solid seal. [See magni-
fied insert in (See Figure 4-11.)] The split of seals
and backup rings must be positioned so as not to be
in alignment with each other.
8. Using suitable protection, clamp the cylinder rod in
a vise or similar holding fixture as close to piston as
possible.
9. Carefully thread the piston on the cylinder rod hand
tight, ensuring that the o-ring and back-up rings are
not damaged or dislodged.
10. 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.
11. Assemble the tapered bushing loosely into the pis-
ton and insert JLG capscrews (not vendor cap-
screws) through the drilled holes in the bushing and
into the tapped holes in the piston.
Figure 4-9. Wiper Seal Installation
Figure 4-10. Installation of Head Seal Kit
Figure 4-11. Piston Seal Kit Installation