JLG 660SJ Service Manual - Manual (Page 216)

SECTION 5 - HYDRAULICS
5-6 – JLG Lift – 3121202
13. Insert the cap screw(s) in the threaded holes in the
outer piece of the tapered bushing. Progressively
tighten the cap screw(s) until the bushing is loose
on the piston.
14. Remove the bushing from the piston.
15. Screw the piston CCW, by hand, and remove the
piston from cylinder rod.
16. Remove and discard the piston o-rings, seal rings,
and backup rings.
17. Remove piston spacer, if applicable, from the rod.
18. Remove the rod from the holding fixture. Remove
the cylinder head gland and retainer plate, if applica-
ble. Discard the o-rings, back-up rings, rod seals,
and wiper seals.
Cleaning and Inspection
1. Clean all parts thoroughly in an approved cleaning
solvent.
2. Inspect the cylinder rod for scoring, tapering, ovality,
or other damage. If necessary, dress rod with
Scotch Brite or equivalent. Replace rod if necessary.
3. Inspect threaded portion of rod for excessive dam-
age. Dress threads as necessary.
4. Inspect inner surface of cylinder barrel tube for scor-
ing or other damage. Check inside diameter for
tapering or ovality. Replace if necessary.
5. Inspect threaded portion of barrel for damage. Dress
threads as necessary.
6. Inspect piston surface for damage and scoring and
for distortion. Dress piston surface or replace piston
as necessary.
7. Inspect threaded portion of piston for damage.
Dress threads as necessary.
8. Inspect seal and o-ring grooves in piston for burrs
and sharp edges. Dress applicable surfaces as nec-
essary.
9. Inspect cylinder head inside diameter for scoring or
other damage and for ovality and tapering. Replace
as necessary.
10. Inspect threaded portion of head for damage. Dress
threads as necessary.
11. Inspect seal and o-ring grooves in head for burrs
and sharp edges. Dress applicable surfaces as nec-
essary.
12. Inspect cylinder head outside diameter for scoring
or other damage and ovality and tapering. Replace
as necessary.
13. If applicable, inspect rod and barrel bearings for
signs of correct excessive wear or damage. Replace
as necessary.
a. Thoroughly clean hole, (steel bushing) of burrs,
dirt etc. to facilitate bearing installation.
b. Inspect steel bushing for wear or other damage.
If steel bushing is worn or damaged, rod/barrel
must be replaced.
c. Lubricate inside of steel bushing with WD40
prior to bearing installation.
d. Using an arbor of the correct size, carefully
press the bearing into steel bushing.
NOTE: Install pin into the composite bearing dry. Lubrication
is not required with nickel plated pins and bearings.
14. Inspect travel limiting collar or spacer for burrs and
sharp edges. If necessary, dress inside diameter
surface with Scotch Brite or equivalent.
15. If applicable, inspect port block fittings and holding
valve. Replace as necessary.
16. Inspect the oil ports for blockage or the presence of
dirt or other foreign material. Repair as necessary.
17. If applicable, inspect piston rings for cracks or other
damage. Replace as necessary.
Figure 5-5. Tapered Bushing Removal
Figure 5-6. Composite Bearing Installation