JLG 120HX ANSI Service Manual User Manual
Page 35
SECTION 2 - PROCEDURES
3120686
– JLG Lift –
2-15
6.
Inspect piston surface for damage and scoring and
for distortion. Dress piston surface or replace piston
as necessary.
7.
Inspect seal and o-ring grooves in piston for burrs
and sharp edges. Dress applicable surfaces as nec-
essary.
8.
Inspect cylinder head inside diameter for scoring or
other damage and for ovality and tapering. Replace
as necessary.
9.
Inspect seal and o-ring grooves in head for burrs
and sharp edges. Dress applicable surfaces as nec-
essary.
10.
If applicable, inspect cylinder head retainer or end
cap for surface or thread damage. Repair or replace
as necessary.
11.
Inspect cylinder head outside diameter for scoring
or other damage and ovality and tapering. Replace
as necessary.
12.
If applicable, inspect thread ring for scoring or other
damage. Dress threads or applicable surfaces as
necessary.
13.
If applicable, inspect rod and barrel bushings for
signs of correct lubrication and excessive wear.
Replace as necessary.
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. See your JLG Parts Manual.
NOTE: Apply a light film of hydraulic oil to all components
prior to assembly.
WHEN INSTALLING NEW “POLY-PAK” TYPE PISTON SEALS,
ENSURE SEALS ARE INSTALLED PROPERLY. REFER TO FIGURE
2-1 FOR CORRECT SEAL ORIENTATION. IMPROPER SEAL
INSTALLATION COULD RESULT IN CYLINDER LEAKAGE AND
IMPROPER CYLINDER OPERATION.
1.
Place a new wiper seal and rod seal into the applica-
ble cylinder head gland grooves.
2.
Carefully install the head gland on the rod, ensuring
that the wiper and rod seals are not damaged or dis-
lodged. Push the head along the rod to the rod end,
as applicable.
3.
Carefully slide the piston spacer on the rod. If appli-
cable, align the oil holes in the rod and the spacer.
Secure the spacer, if applicable.
4.
If applicable, correctly place a new o-ring and back-
up rings in the inner piston diameter groove.
5.
Carefully place the piston on the cylinder rod, ensur-
ing that the o-ring and back-up rings are not dam-
aged or dislodged.
6.
Using suitable protection, clamp the cylinder rod in
a vise or similar holding fixture as close to the piston
as possible.
7.
Push the piston onto the rod until it abuts the spacer
end and install the attaching nut.
IF CYLINDER IS EQUIPPED WITH A PISTON NUT, APPLY “LOC-
QUIC PRIMER T” AND LOCTITE #242 TO PISTON NUT THREADS,
THEN TIGHTEN NUT TO TORQUE SHOWN IN TABLE 2-2.
Figure 2-5. Poly-Pak Seal Installation