JLG 1230ES Service Manual - Manual (Page 117)

SECTION 6 - MAST COMPONENTS
3121222 – JLG Lift – 6-17
Hydraulic Cylinder Component Inspection
Cylinder Rod
There should be no scratches or pits deep enough to
catch the fingernail. Pits that go to the base metal are
unacceptable. Scratches that catch the fingernail but are
not to the base metal, less than 0.5 inch long and primarily
in the circumferential direction are acceptable provided
they cannot cut the rod seal. Chrome should be present
over the entire surface of the rod and the lack thereof is
unacceptable. In the event that an unacceptable condition
occurs, the rod should be repaired or replaced.
Cylinder Head (Gland)
Visually inspect the inside bore for scratches or polishing.
Deep scratches are unacceptable. Polishing indicates
uneven loading and when this occurs, the bore should be
checked for out-of-roundness. If out-of-roundness exceed
0.007", this is unacceptable. Check the condition of the
dynamic seals (wiper, rod seals) looking particularly for
metallic particles embedded in the seal surface. It is nor-
mal to cut the static seal on the retaining ring groove upon
disassembly. Remove the rod seal, static o-ring and
backup and rod wiper. Damage to the seal grooves, par-
ticularly on the sealing surfaces, is unacceptable. In the
event that an unacceptable condition occurs, the head
should be replaced.
Piston
Visually inspect the outside surface for scratches or pol-
ishing. Deep scratches are unacceptable. Polishing indi-
cates uneven loading and when this occurs, the diameter
should be checked for out-of-roundness. If out-of-round-
ness exceeds 0.007", this is unacceptable. Check the con-
dition of the dynamic seals and bearings looking
particularly for metallic particles embedded in the bearing
and in the piston seal surface. Remove the seals and
bearings. Damage to the seal grooves, particularly on the
sealing surfaces, is unacceptable. In the event that an
unacceptable condition occurs, the piston should be
replaced.
Tube Assembly
Visually inspect the inside bore for scratches and pits.
There should be no scratches or pits deep enough to
catch the fingernail. Scratches that catch the fingernail but
are less than 0.5 inch long and primarily in the circumfer-
ential direction are acceptable provided they cannot cut
the piston seal. The roughness of the bore should be
between 10 and 20 μ inches RMS. Significant variation
(greater than 8 μ inches difference) are unacceptable. In
the event that an unacceptable condition occurs, the tube
assembly should be repaired or replaced.
Hydraulic Cylinder - Assembly
NOTE: Prior to cylinder assembly, ensure the proper JLG
seal kits are used, see the JLG Parts Manual.
APPLY A LIGHT FILM OF THE HYDRAULIC OIL TO BE USED FOR
OPERATION TO ALL CO MPONENTS TO BE ASSEM BLED,
EXCEPT THE THREADED AREAS WHERE LOCTITE IS TO BE
APPLIED.
Cylinder Assembly
This procedure is same for all three cylinders.
1. Reassemble the piston/compression spring/piston
guide onto the end of the cylinder rod secure using
the piston retaining ring. (See Figure 6-20.)
EXTREME CARE SHOULD BE TAKEN WHEN INSTALLING THE
CYLINDER ROD, HEAD, AND PISTON INTO THE CYLINDER BAR-
REL. AVOID PULLING THE ROD OFF CENTER, WHICH COULD
CAUSE DAMAGE TO THE PISTON AND CYLINDER BARREL SUR-
FACES.
2. Lubricate the piston assembly and rod with hydrau-
lic oil, slide the rod assembly into the cylinder barrel.
3. Install new o-rings and seals into the cylinder head
gland.
4. Lubricate the o-rings and seals with hydraulic oil
then carefully slide the gland assembly onto the end
of the cylinder rod and into the end of the cylinder
barrel.
5. Rotate the gland until the hole for the retaining ring
is lined up with the hole in the cylinder barrel.
6. Insert a new retaining ring into the slot with the hook
end of the retaining ring facing down and inserted
into the hole in the gland. (See Figure 6-19.)
7. Using the proper spanner wrench (48mm - 1.889"
diameter) slowly rotate the gland 360° until all the
retaining ring has pulled into the slot. Fill the open
slot with a silicone sealant to prevent dirt from enter-
ing.