JLG 600SC_660SJC Service Manual - Manual (Page 169)

SECTION 5 - HYDRAULICS
3121607 – JLG Lift – 5-25
8. Using suitable protection, clamp cylinder rod in a vise or
similar holding fixture as close to piston as possible.
9. Loosen and remove nut attaching piston to rod. Remove
piston.
10. Loosen and remove cap screw(s), if applicable, attaching
tapered bushing to piston.
11. Insert cap screw(s) in threaded holes in outer piece of
tapered bushing. Progressively tighten cap screw(s) until
bushing is loose on piston.
12. Remove tapered bushing from piston.
13. Screw piston counter-clockwise by hand and remove
from cylinder rod.
Figure 5-46. Tapered Bushing Removal
14. Remove and discard piston O-rings, seal rings, and
backup rings.
15. Remove piston spacer, if applicable, from rod.
16. 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 parts thoroughly with 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 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, or 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.
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 necessary.
12. Inspect cylinder head outside diameter for scoring,
damage, 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 the steel bushing with WD40
prior to bearing installation.
NOTE: Lubrication is not required with nickel plated pins and
bearings. Install pin in composite bushing dry.
d. Press composite bushing into barrel or rod bushing
with correct size arbor.
Figure 5-47. Composite Bushing Installation
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 oil ports for blockage or presence of dirt or other
foreign material. Repair as necessary.
17. If applicable, inspect piston rings for cracks or other
damage. Replace as necessary.