JLG 4017RS Service Manual - Manual (Page 150)

Hydraulic System
8-20 3614RS, 4017RS
Some cylinder parts are sealed with a special organic sealant
and locking compound. Before attempting to disassemble
these parts, remove any accessible seals from the area of the
bonded parts. Wipe off any hydraulic oil, then heat the part(s)
uniformly to break the bond. A temperature of 149-204° C
(300-400° F) will destroy the bond. Avoid overheating, or the
parts may become distorted or damaged. Apply sufficient
torque for removal while the parts are still hot. The sealant
often leaves a white, powdery residue on threads and other
parts, which must be removed by brushing with a soft brass
wire brush prior to reassembly.
9. Remove the piston head from the rod and carefully slide
the head gland off the end of the rod.
10. Remove all seals, back-up rings and o-rings from the
piston head and all seals, back-up rings and o-rings
from the head gland.
Note: The head gland bearing will need to be inspected to
determine if replacement is necessary.
DO NOT attempt to salvage cylinder seals, sealing rings or o-
rings. ALWAYS use a new, complete seal kit when rebuilding
hydraulic components. Consult the parts catalog for
ordering information.
b. Cylinder Cleaning Instructions
1. Discard all seals, back-up rings and o-rings. Replace with
new items from seal kit to ensure proper cylinder
function.
2. Clean all metal parts with an approved cleaning solvent
such as trichlorethylene. Carefully clean cavities,
grooves, threads, etc.
Note: If a white powdery residue is present on threads or parts,
it can be removed by using a soft brass wire brush. Wipe clean
with Loctite
® Cleaner prior to reassembly.
c. Cylinder Inspection
1. Inspect internal surfaces and all parts for wear, damage,
etc. If the inner surface of the cylinder barrel does not
display a smooth finish, or is scored or damaged in any
way, replace the barrel.
2. Remove light scratches on the piston, head gland, rod
or inner surface of the cylinder barrel with a 400-600 grit
emery cloth. Use the emery cloth in a rotary motion to
polish out and blend the scratch(es) into the
surrounding surface.
3. Check the piston rod assembly for run-out. If the rod is
bent, it must be replaced.
d. General Cylinder Assembly Instructions
1. Use the proper tools for specific installation tasks. Clean
tools are required for installation.
2. Install new seals, back-up rings and o-rings on the
piston and new seals, back-up rings, o-rings and
bearing on the head gland.
Note: The extend/retract cylinder has a spacer that MUST be
installed over the rod
AFTER the head gland and BEFORE the
piston head.
3. Fasten the rod eye in a soft-jawed vise, and place a
padded support under and near the threaded end of
the rod to prevent any damage to the rod.
Note: Protect the finish on the cylinder rod at all times.
Damage to the surface of the rod can cause seal failure.
4. Lubricate and slide the head gland over the cylinder
rod. Install the piston head on to the end of the cylinder
rod. Apply Loctite
® 243 TM and install the set screw in the
piston head. Refer to Section 8.10.4, “Cylinder Torque
Specifications” for torque specifications for the piston
head and the set screw.
Note: Avoid using excess force when clamping the cylinder
barrel in a vise. Apply only enough force to hold the cylinder
barrel securely. Excessive force can damage the cylinder barrel.
5. Place the cylinder barrel in a soft-jawed vise or other
acceptable holding devise.
Note: When sliding the rod and piston assembly into the
cylinder barrel, prevent the threaded end of the cylinder barrel
from damaging the piston head. Keep the cylinder rod centered
within the barrel to prevent binding.
6. Carefully insert the cylinder rod assembly into the
cylinder barrel.