JLG 3246ES Service Manual - Manual (Page 116)

SECTION 4 - HYDRAULICS
4-14 – JLG Lift – 3121166
1. Using suitable protection, clamp the cylinder rod
in a vise or similar holding fixture as close to piston
as possible.
2. Carefully thread the piston on the cylinder rod
hand tight, ensuring that the o-ring and back-up
rings are not damaged or dislodged.
3. Thread the piston onto the rod until it abuts the
spacer end and install the tapered bushing.
NOTE: When installing the tapered bushing, piston and
mating end of rod must be free of oil.
4. Assemble the tapered bushing loosely into the pis-
ton and insert JLG capscrews (not vendor cap-
screws) through the drilled holes in the bushing
and into the tapped holes in the piston.
5. Tighten the capscrews evenly and progressively in
rotation to the specified torque value.
6. After the screws have been torqued, tap the
tapered bushing with a hammer (16 to 24 oz.) and
brass shaft (approximately 3/4" in diameter) as fol-
lows;
a. Place the shaft against the cylinder rod and in
contac t with the bushing in th e spaces
between the capscrews.
b. Tap each space once; this means the tapered
bushing is tapped 3 times as there are 3 spaces
between the capscrews.
7. Retorque the capscrews evenly and progressively
in rotation to the specified torque value.
8. Remove the cylinder rod from the holding fixture.
9. Place new guide locks and seals in the applicable
outside diameter grooves of the cylinder piston.
(See Figure 4-10.)
10. Position the cylinder barrel in a suitable holding
fixture.
NOTICE
EXTREME CARE SHOULD BE TAKEN WHEN INSTALLING THE CYL-
INDER ROD, HEAD, AND PISTON. AVOID PULLING THE ROD OFF-
CENTER, WHICH COULD CAUSE DAMAGE TO THE PISTON AND
CYLINDER BARREL SURFACES.
11. With the barrel clamped securely, and while ade-
quately supporting the rod, insert the piston end
into the barrel cylinder. Ensure that the piston
loading o-ring and seal ring are not damaged or
dislodged.
12. Continue pushing the rod into the barrel until the
cylinder head gland can be inserted into the barrel
cylinder.
13. Secure the cylinder head gland using the washer
ring and socket head bolts.
14. 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.
15. If applicable, install the cartridge-type holding
valve and fittings in the rod port block, using new
o-rings as applicable. (See Table 4-3, Holding Valve
Torque Specifications).
BACKUP
RINGS
O-RING
PISTON
SPLIT SEAL
SEAL
SPLIT BACKUP RING
T - RING
SPLIT
BACKUP
RING
Figure 4-10. Piston Seal Kit Installation
Table 4-2. Cylinder Piston Nut Torque Specifications
Description
Nut Torque
Value
Setscrew
torque Value
Lift Cylinder
250-300 ft lb
(339-407 Nm)
N/A
Figure 4-11. Rod Assembly Installation