JLG 19AMI (3120758) Service Manual - Manual (Page 35)

SECTION 2 - SERVICE PROCEDURES
3120758 – JLG Lift – 2-21
Cylinder Assembly
(See Figure 2-2.)
1. Rinse the inside of the tube with hydraulic fluid and
allow to drain. A high-pressure rinse followed by a
wipe with a lint-free rag is preferable. Clean all inter-
nal components of any foreign material.
2. Lubricate the head and all seals with hydraulic fluid
prior to installation. Install the seal, wiper, o-ring,
back-up ring, and retraining ring to the cylinder
head.
3. Lubricate the piston and all components with
hydraulic fluid. Install the seal and wear ring to the
piston.
NOTE: Re-check that seals are not twisted or pinched and
are properly seated.
4. Place the rod on a clean table. Install the static o-
ring seal into the groove on the piston end of the
rod.
5. Install the head followed by the piston onto the rod
noting the proper orientation of each component.
Torque the piston nut to 175-200 ft. lbs.
6. When the rod assembly is ready to be installed into
the tube, liberally apply an anti-seize lubricant to the
head outer surface, especially the static seal.
7. Next dip the entire rod assembly into hydraulic fluid
and stuff this assembly into the tube. Watch the
seals as they pass over the rod port (if visible) to be
sure they are not nicked or cut.
8. Install the head until the retaining ring seats in it’s
groove.
Installation
1. Remove the plastic plugs from the cylinder.
2. Pull rod out of cylinder approximately 3 ft.
NOTE: The following step is easier done with two people,
one to slide the cylinder into the mast, the other to
guide the rod into the cylinder block at the top of the
mast.
3. Slide the cylinder into the mast and install the rod
into the cylinder attach block.
4. Apply Loctite #222 (purple) to the setscrew securing
the lift cylinder rod to the sheave wheel anchor block
at the top of mast section-2.
5. Install the setscrew in the cylinder attach block at the
top of the mast, coat the threads of the setscrew with
Loctite (RC/#640-blue) before tightening.
6. Original Design Cylinder Mount: Install the cylin-
der mount and cylinder mounting plates into the bot-
tom of the mast section-1. Shim to eliminate any
side clearance to prevent any strain on the sides of
the mast when the bolts are tightened.
7. New Design Cylinder Mount: Install the cylinder
mounting plates at the bottom of the mast section-1.
Mount plates two each side, using the the (2) two
long pass through bolts and nuts, apply Loctite
#242 to the bolt threads before tightening nuts.
8. Original Design Cylinder: Clamp the cylinder in the
mounting journal of the cylinder mount. Apply Loc-
tite #242 to the journal bolt threads and torque to 85
ft. lbs. Align the hole in the mounting journal with the
hole in the cylinder and Install the (1) 5/16" bolt.
New Design Cylinder: Install the mounting pin
through the side mounting brackets and the cylinder
valve body and through the mounting brackets on
the other side of the mast. Install the snap rings to
each end of the mounting pin.
9. Connect the hydraulic fittings and lines, (new fittings
should be used).
10. Slide the mast together (stowed position) from the
top of the mast.
11. Stand machine upright on it’s base wheels.
12. Connect the hydraulic line fittings at the pump.
13. Check oil level in the hydraulic oil reservoir, add oil
to fill line, if necessary.
14. Install the ground station (pump) cover.
15. Set-up machine for operation and cycle mast (up
and down) approximately 3 ft. to 4 ft. a few times.
16. Check the hydraulic oil reservoir again, add oil to the
fill line.