JLG 450A_AJ Series II Service Manual - Manual (Page 312)

SECTION 5 - HYDRAULICS
5-22 – JLG Lift – 3121180
USE EXTREME CARE WHEN REMOVING CYLINDER ROD, HEAD,
AND PISTON. PULLING ROD OFF-CENTER CAN DAMAGE PISTON
AND CYLINDER BARREL SURFACES.
9. With barrel clamped securely, apply pressure to rod
pulling device and carefully withdraw complete rod
assembly from cylinder barrel.
10. Using suitable protection, clamp the cylinder rod in
a vise or similar holding fixture as close to the piston
as possible.
NOTE: Step 11 applies only to the steer cylinder.
11. Loosen and remove nut which attaches piston to
rod, and remove piston.
12. Loosen and remove cap screw(s), if applicable,
which attach tapered bushing to piston.
13. Insert cap screw(s) in threaded holes in outer piece
of tapered bushing. Progressively tighten cap
screw(s) until bushing is loose on piston.
14. Remove bushing from piston.
15. Screw piston CCW by hand and remove piston from
cylinder rod.
16. Remove and discard piston O-rings, seal rings, and
backup rings.
17. Remove piston spacer, if applicable, from rod.
18. Remove rod from holding fixture. Remove cylinder
head gland and retainer plate, if applicable. Discard
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 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 surfaces as necessary.
9. Inspect cylinder head inside diameter for scoring or
other damage, and for ovality and tapering. Replace
as necessary.
Figure 5-23. Cylinder Rod Support
Figure 5-24. Tapered Bushing Removal