JLG M4069 ANSI Service Manual - Manual (Page 79)

SECTION 4 - HYDRAULICS
3121122 – JLG Lift – 4-7
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 damage. 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 lubrication and excessive wear. If
necessary, replace bearings as follows:
a. Thoroughly clean steel bushing hole 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 or bar-
rel (as applicable) must be replaced.
c. Using arbor of the correct size, carefully press
the bearing into the steel bushing.
NOTE: Install the cylinder pin into the Garmax bearing dry.
Lubrication is not required with chrome 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.
Assembly
NOTE: Prior to cylinder assembly, ensure that the proper
cylinder seal kit is used.
Apply a light film of hydraulic oil to all components
prior to assembly.
1. Using a special tool, pictured in the following illustra-
tion, install a new rod seal into the applicable cylin-
der head gland groove. Refer to the following
illustration for the proper tool size.
WHEN INSTALLING NEW “POLY-PAK” TYPE PISTON SEALS,
ENSURE SEALS ARE INSTALLED PROPERLY. (SEE FIGURE 4-9.)
FOR CORRECT SEAL ORIENTATION. IMPROPER SEAL INSTALLA-
TION COULD RESULT IN CYLINDER LEAKAGE AND IMPROPER
CYLINDER OPERATION.
GARMAX
BUSHING
Figure 4-4. Oil-lite Bearing Installation
Figure 4-5. Rod Seal Installation