JLG 40H Service Manual - Manual (Page 31)

SECTION 2 - PROCEDURES
3120240 – JLG Lift –
2-11
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.
WHEN REBUILDING THE LIFT, SLAVE LEVEL, TELESCOPE,
STEER (SINGLE ROD), AND EXTEND-A-REACH SLAVE AND LIFT
CYLINDE RS, AP PLY LOCTITE #2 42 TO P IS TON NUT, TH EN
TIGHTEN BOTH SECURELY. (SEE TABLE 2-2 FOR TORQUE SPEC-
IFICATIONS).
NOTE: These cylinders use self-locking knurled cup point
setscrews which should be discarded and replaced
whenever they are removed.
After torquing piston nut spot drill cylinder rod for set-
screws.
8. If applicable, install the setscrew (s) which secure
the piston attaching nut to the diameter groove. (See
Table 2-2 for Torque Specifications).
9. Remove the cylinder rod from the holding fixture.
10. Place new o-rings and seals in the applicable out-
side diameter grooves of both the piston and the cyl-
inder head.
11. 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.
12. With barrel clamped securely, and while adequately
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.
13. Continue pushing the rod into the barrel until the cyl-
inder head gland can be inserted into the barrel cyl-
inder or, if applicable, until the cylinder threads
engage the threads of the barrel.
14. If applicable, secure the cylinder head gland using a
suitable spanner type wrench in the holes provided.
15. If applicable, secure the cylinder head retainer using
a suitable spanner type wrench in the holes pro-
vided.
16. 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.
17. If applicable, install the cartridge-type holding valve
and fittings in the rod port block using new o-rings
as applicable. (See Table 2-2. Holding Valve Torque
Specifications).
IF THE CYLINDER IS TO BE TESTED PRIOR TO INSTALLATION ON
THE MACHINE, EXTREME CARE SHOULD BE USED TO INSURE
THAT TH E OUTER E ND OF TH E ROD IS S UPP ORTE D. US E
EITHER A TRAVELING OVERHEAD HOIST, FORKLIFT, OR OTHER
MEANS TO SUPPORT THE OVERHANGING WEIGHT OF THE
EXTENDING ROD.
NOTE: Steps 18 through 21 apply to the Boom Telescope
Cylinders.
18. Elevate the barrel end of the cylinder to a work
bench or other suitable device.
19. Plug the retract port and supply hydraulic power to
the extend port.
20. Open the bleeder port plug (TP) venting all trapped
air to atmosphere. Retighten the bleeder port plug.
Disconnect the hydraulic power source and remove
plug from retract port.
Figure 2-3. Poly-Pak Seal Installation.