JLG 120HX ANSI Service Manual - Manual (Page 34)

SECTION 2 - PROCEDURES
2-14 – JLG Lift – 3120686
3. If applicable, remove the cartridge-type holding
valve and fittings from the cylinder port block. Dis-
card o-rings.
4. Place the cylinder barrel into a suitable holding fix-
ture. Tap around outside of cylinder head retainer
with a suitable hammer to shatter loctite.
5. Using a suitable spanner wrench, loosen the cylin-
der head retainer, if applicable, and/or cylinder head
gland, and remove from cylinder barrel.
6. Attach a suitable pulling device to the cylinder rod
port block end or cylinder rod end, as applicable.
EXTREME CARE SHOULD BE TAKEN WHEN REMOVING THE CYL-
INDER ROD, HEAD, AND PISTON. AVOID PULLING THE ROD OFF-
CENTER, WHICH COULD CAUSE DAMAGE TO THE PISTON AND
CYLINDER BARREL SURFACES.
7. With the barrel clamped securely, apply pressure to
the rod pulling device and carefully withdraw the
complete rod assembly from the cylinder barrel.
ONCE THE HEAD GLAND HAS CLEARED THE CYLINDER CASE
MOUTH, THE ROD MUST BE SUPPORTED CLOSE TO THE CYLIN-
DER CASE PRIOR TO THE PISTON BEING PULLED PAST THE
CYLINDER CASE THREADS. THIS IS DONE TO AVOID DAMAGE
TO THE CYLINDER CASE THREADS, AND/OR THE PISTON AND
PISTON SEALS.
8. Using suitable protection, clamp the cylinder rod in
a vise or similar holding fixture as close to the piston
as possible.
9. Remove the set screw(s), if applicable, and nut
which attach the piston to the rod, and remove the
piston. Discard nylon point set screws.
10. Remove the piston rings.
11. Remove and discard the piston o-rings, seal rings,
and backup rings.
12. Remove the set screw, if applicable, piston spacer,
and wear ring, if applicable, from the rod.
13. Remove the rod from the holding fixture. Remove
the cylinder head gland and retainer, if applicable.
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.
RO
D
S
U
P
P
O
RT
SUPPORT
TABLE
ROD CLAMP
PROTECTED
BARREL CLAMP
Figure 2-3. Cylinder Barrel Support
RO
D
S
U
P
P
O
RT
SUPPORT
TABLE SUPPORT
TABLE
ROD CLAMP
PROTECTED
Figure 2-4. Cylinder Rod Support