JLG 450A_AJ Series II Service Manual - Manual (Page 256)

SECTION 5 - HYDRAULICS
5-16 – JLG Lift – 3121290
6. Using suitable protection, clamp cylinder rod in a vise or
similar holding fixture as close to piston as possible.
7. Remove retainer from end of rod.
8. Unscrew and remove piston assembly.
9. 450A only. Remove spacer.
10. Remove head assembly from rod.
CLEANING AND INSPECTION
1. Clean all parts thoroughly in an approved cleaning sol-
vent.
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 damage.
Dress threads as necessary.
4. Inspect inner surface of cylinder barrel tube for scoring
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, scoring, and distor-
tion. 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, ovality, and tapering. Replace as needed.
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 surfaces as necessary.
12. Inspect cylinder head outside diameter for scoring or
other damage, ovality, and tapering. Replace as needed.
13. Inspect rod and barrel bearings for signs of excessive
wear or damage. Replace as necessary.
a. Thoroughly clean hole (steel bushing) of burrs, dirt,
or other contamination.
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 before
installing composite bushings.
d. Using a correct size arbor, press bearing into steel
bushing.
NOTE: Lubrication is not required with nickel plated pins and
bearings. Install pin in composite bushing dry.
Figure 5-27. Composite Bushing Installation
14. Inspect spacer (450A only) for burrs and sharp edges.
Dress inside diameter surface with Scotch Brite or equiv-
alent as needed.
15. Inspect oil ports for blockage or presence of dirt or other
foreign material. Repair as necessary.
16. Inspect piston rings for cracks or other damage. Replace
as needed.
ASSEMBLY
NOTE: Use proper cylinder seal kit for cylinder assembly. See your
JLG Parts Manual.
Apply a light film of hydraulic oil to all components before
assembly.
1. Use seal tool to install new rod seal in cylinder head
gland groove.
Figure 5-28. Rod Seal Installation