JLG M4069 Service Manual - Manual (Page 81)

SECTION 4 - HYDRAULICS
3121824 – JLG Lift – 4-9
14. With the barrel clamped securely, and while ade-
quately supporting the rod, insert the piston end into
the cylinder barrel. Ensure that the piston loading o-
ring and seal ring are not damaged or dislodged.
15. Continue pushing the rod into the barrel until the cyl-
inder head gland can be inserted into the cylinder
barrel.
16. Secure the cylinder head gland using the washer
ring and socket head bolts.
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.
WHEN REBUILDING THE LIFT CYLINDERS, APPLY LOCTITE 242
TO PISTON NUT AND SETSCREWS.
NOTE: These cylinders use setscrews which should be dis-
carded and replaced whenever they are removed.
19. Remove cylinder rod from the holding fixture.
20. Place new o-rings and seals in the applicable out-
side diameter grooves of both the piston and the cyl-
inder head.
21. Position the cylinder barrel in a suitable holding fix-
ture.
EXTREME CARE SHOULD BE TAKEN WHEN INSTALLING THE
CYLINDER ROD, HEAD AND PISTON. AVOID PULLING THE ROD
OFF-CENTER, WHICH COULD CAUSE DAMAGE TO THE PISTON
AND CYLINDER BARREL SURFACES.
Figure 4-9. Poly-Pak Piston Seal Installation
Figure 4-10. Rod Assembly Installation
Table 4-2. Cylinder Piston Nut Torque Specifications
Description
Nut Torque Value
(Wet)
Lift Cylinder
(3369)
1120 - 1400 Nm
(800 - 1000 ft lbs)
LIft Cylinder
(4069)
1575 - 1925 Nm
(1125 - 1375 ft lbs)
Steer Cylinder See Applicable Figure
Table 4-3. Holding Valve Torque Specifications
Description Torque Value
Sun - 7/8 hex M20 x1.5 thds
41 - 48 Nm
(30 - 35 ft lbs)
Sun - 1-1/8 hex 1 - 14 UNS thds
61 - 68 Nm
(45 - 50 ft lbs)
Sun - 1-1/4 hex M36 x 2 thds
204 - 207 Nm
(150 - 160 ft lbs)
Racine - 1-1/8 hex 1-1/16 - 12 thds
68 -75 Nm
(50 - 55 ft lbs)
Racine - 1-3/8 hex 1-3/16 - 12 thds
102 - 109 Nm
(75 - 80 ft lbs)
Racine - 1-7/8 hex 1-5/8 - 12 thds
136 - 149 Nm
(100 - 110 ft lbs)