SkyTrak 3606 Service Manual - Manual (Page 280)

Section 9
9-86
9.10 CYLINDERS
There are many factors involved with the proper disas-
sembly, cleaning, inspection, repair and reassembly of
hydraulic cylinders; therefore, only qualified professionals
with proper training, supervision, tools and equipment
should rebuild the cylinders used on this vehicle.
For example, special pin spanner wrenches of the correct
size are needed to disassemble the cylinders. Also, the
hoist/lower cylinder rod locknut must be torqued to 1550-
1750 lb/ft (2034-2305 Nm); this requires a special torque
wrench and/or torque multiplier. If the proper knowledge
and equipment are not available, the cylinders must be
sent out for rebuilding by a competent professional at a
company that specializes in rebuilding agricultural and
industrial heavy-equipment hydraulic cylinders.
Rebuild cylinders only in a clean, well-lighted area where
all components can be carefully and thoroughly
inspected. If leaving a cylinder dismantled for any length
of time longer than the immediate rebuilding period, and
especially in high-humidity environments, coat the metal
parts with a suitable preservative and place them in pro-
tective storage.
Refer to the specific instructions for removal, rebuilding
and installation of each cylinder.
a. General Cylinder Disassembly Instructions
Some cylinder parts are sealed with a “special organic”
sealant and locking compound. Before attempting to dis-
assemble 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 tem-
perature of 300° F to 400° F (149° C to 204° C) 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.
Note: Significant pressure may be trapped inside the
cylinder. Exercise caution when removing counter-bal-
ance valves from a cylinder and when disassembling a
cylinder with a pilot-to-open check valve.
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 cata-
log for ordering information.
Note: An additional O-ring may be included at the base
of the cylinder rod. This additional O-ring may be
discarded, as it served only in a temporarily protective
role to keep paint off the rod while the cylinder was
painted at the factory.
b. General Cylinder Cleaning Instructions
Clean all reusable metal parts thoroughly after disassem-
bly and prior to inspection. Use an approved solvent such
as trichlorethylene.
c. General Cylinder Assembly Instructions
1. Before reassembly, assure that parts are clean and
free from foreign matter. Use an approved solvent for
cleaning, such as trichlorethylene.
2. Use the proper tools for specific installation tasks.
Clean tools are required for installation.
3. Protect the finish on the rod at all times. Damage to
the rod can cause premature seal failure.
4. Always use new O-rings, seals, gaskets, etc. DO
NOT over-stretch seals, wipers and O-rings. After
installing such parts, verify that they are not twisted in
their grooves.
5. To aid in installation, lubricate piston seals and the
seal installation path with clean, filtered hydraulic oil.
6. Lubricate the outer surfaces of the seals and O-rings
and the inside of the tube, piston and head gland with
clean hydraulic oil from a filtered source. Use a
suitable installation or compression tool when
installing the piston and head gland into the cylinder
to help prevent twisting or damaging the seals and O-
rings. When sliding the rod and piston assembly in
the tube, DO NOT damage the piston by scraping it
against the threads in the tube. Keep the rod in line
with the tube to prevent binding.
7. Follow the manufacturer's instructions when applying
primer, locking or retaining compounds that are
specified in the cylinder assembly procedures. The
use of primer is recommended in some cases to
decrease cure time. Allow sealant to cure fully before
proceeding with the assembly procedure. The curing
process may be hastened by the use of a heat gun to
blow warm, dry air on the parts.
8. After assembling a cylinder, test the cylinder at low
operating pressures. Verify that the piston and rod
move freely in both directions.
9. Increase the operating pressure to the maximum
pressure recommended for the cylinder. Check for
external leakage and for free movement in both
directions.
10. Retracting the piston fully. Cap the hydraulic fittings.
WARNING: To help prevent severe burns, pro-
ceed with caution when applying heat to parts.
Avoid the use of excessive heat, which will
damage parts and make them unusable.
Model 3606 • Origin 10/99