JLG 2658E3 Service Manual - Manual (Page 23)

SECTION 2 - PROCEDURES
3120878 – JLG Lift – 2-11
17. After the cylinder has been reassembled, the rod
should be pushed all the way in (fully retracted) prior
to the reinstallation of any holding valve or valves.
18. If applicable, install the cartridge-type holding valve
and fittings in the port block using new o-rings as
applicable.
2.12 LIFT CYLINDER REPAIR
Disassembly
DISASSEMBLY OF THE CYLINDER SHOULD BE PERFORMED ON
A CLEAN WORK SURFACE IN A DIRT FREE WORK AREA. BE
SURE TO CLEAN ALL DIRT OR OTHER FOREIGN SUBSTANCES
FROM CYLINDER OPENINGS - PARTICULARY AT THE HEAD.
1. Connect a suitable auxiliary hydraulic power source
to the cylinder port block fitting.
DO NOT FU LLY EXTEN D CYLINDER TO END OF STROKE.
RETRACT CYLINDER SLIGHTLY TO AVOID TRAPPING PRES-
SURE.
2. Operate the hydraulic power source and extend the
cylinder. Shut down and disconnect the power
source. Adequately support the cylinder rod, if appli-
cable.
3. Remove the cartridge-type holding valve and fittings
from the cylinder port block. Discard o-rings.
4. Place the cylinder barrel into a suitable holding fix-
ture.
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.
5. Using a suitable spanner wrench inserted in the
holes provided, turn the cylinder head counter-
clockwise to remove it from the cylinder barrel. If the
head is difficult to turn or moves erratically, tap the
tube adjacent to the head with a brass or plastic
mallet while turning it.
6. Attach a suitable pulling device to the cylinder rod
end.
7. With the barrel clamped securely, apply pressure to
the rod pulling device and carefully withdraw the
complete rod assembly from the cylinder barrel.
8. Using suitable protection, clamp the cylinder rod in
a vise or similar holding fixture as close to the piston
and head as possible.
9. Remove the lock nut which attaches the piston to
the rod, and remove the piston.
10. Slide the head off the rod from the piston end.
11. Remove and discard the sealing o-ring, wiper, u-cup
seal, static o-ring, static back-up ring and wear ring.
12. Remove the piston guidelock ring.
13. Remove and discard the piston o-ring and seals,
then remove the piston spacer.
14. 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 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
12.7 mm (0.5 inch) long and primarily in the circum-
Table 2-1. Cylinder Component Torque Specifications
Component Torque Value (w/Loctite)
Tapered Bushing Retaining
Screws - Lift Cylinder 108 Nm
(80 ft lb)
Head Retaining Screws 12 Nm
(9 ft lb)
Piston Nut - 1532E3/1932E3 508-610Nm
(375-450 lb)
Piston Nut - 2033E3/2046E3/
2646E3/2658E3 1085-1356 Nm
(800-1000 ft lb)
Figure 2-14. Rod Assembly Installation