Skyjack SJ519 TH, Service Manual

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SJ519 TH 216942AC
Hydraulic System & Component Maintenance and Repair Section 1 – Scheduled Maintenance
1.3 Hydraulic System &
Component Maintenance
and Repair
The following points should be kept in mind when
working on the hydraulic system or any component:
WARNING
Escaping fluid from a hydraulic pressure leak can
damage your eyes, penetrate the skin and cause
serious injury. Use proper personal preotection at
all times.
1. Any structure has limits of strength and
durability. To prevent failure of structural parts of
hydraulic components, relief valves which limit
pressure to safe operating values are included in
the hydraulic circuits.
2. Tolerance of working parts in the hydraulic
system is very close. Even small amounts of dirt
or foreign materials in the system can cause
wear or damage to components, as well as
general faulty operation of the hydraulic system.
Every precaution must be taken to assure
absolute cleanliness of the hydraulic oil.
3. Whenever there is a hydraulic system failure
which gives reason to believe that there are
metal particles or foreign materials in the system,
drain and flush the entire system and replace the
filter cartridges. A complete change of oil must
be performed under these circumstances.
4. Whenever the hydraulic system is drained,
check the magnets in the hydraulic reservoir for
metal particles. If metal particles are present,
flush the entire system and add a new change
of oil. The presence of metal particles also may
indicate the possibility of imminent component
failure. A very small amount of fine particles is
normal.
5. All containers and funnels used in handling
hydraulic oil must be absolutely clean. Use a
funnel when necessary for filling the hydraulic
oil reservoir, and fill the reservoir only through
the filter opening. The use of cloth to strain the
oil should be avoided to prevent lint from getting
into the system.
6. When removing any hydraulic component,
be sure to cap and tag all hydraulic lines
involved. Also, plug the ports of the removed
components.
7. All hydraulic components must be disassembled
in spotlessly clean surroundings. During
disassembly, pay particular attention to
the identification of parts to assure proper
reassembly. Clean all metal parts in a clean
mineral oil solvent. Be sure to thoroughly clean
all internal passages. After the parts have been
dried thoroughly, lay them on a clean, lint-free
surface for inspection.
8. Replace all O-rings and seals when overhauling
any component. Lubricate all parts with clean
hydraulic oil before reassembly. Use small
amounts of petroleum jelly to hold O-rings in
place during assembly.
9. Be sure to replace any lost hydraulic oil when
completing the installation of the repaired
component, and bleed any air from the system
when required.
10. All hydraulic connections must be kept tight. A
loose connection in a pressure line will permit
the oil to leak out or air to be drawn into the
system. Air in the system can cause damage
to the components and noisy or erratic system
operation.
1.3-1 Maintenance Hints
Three simple maintenance procedures have the
greatest effect on the hydraulic system performance,
efficiency and life. Yet, the very simplicity of them may
be the reason they are so often overlooked. They are
simply these:
1. Change filters annually. The filters will need
to be changed more often depending on the
operating conditions. Dirty, dusty, high moisture
environments may cause the hydraulic system
to be contaminated more quickly.
2. Maintain a sufficient quantity of clean hydraulic
oil of the proper type and viscosity in the
hydraulic reservoir.
3. Keep all connections tight.