SECTION 2 - GENERAL
2-4
31215031
2.3
LUBRICATION AND INFORMATION
Hydraulic System
1.
The primary enemy of a hydraulic system is contamina-
tion. Contaminants can enter the system by using inade-
quate hydraulic oil; allowing moisture, grease, filings,
sealing components, sand, or other contaminants to
enter during maintenance; or allowing the pump to cav-
itate due to insufficient system warm-up or leaks in
pump supply (suction) lines.
2.
Design and manufacturing tolerances of component
working parts are very close. The smallest amount of dirt
or other contamination entering a system can cause
wear or damage to components and faulty operation.
Take every precaution to keep hydraulic oil clean -
including reserve oil in storage. Check, clean, and
replace hydraulic system filters as at intervals specified
in the Lubrication Chart in Section 1. Always examine fil-
ters for metal particles.
3.
Cloudy oils indicate high moisture content which per-
mits organic growth and causes oxidation or corrosion.
If this condition occurs, the system must be drained,
flushed, and refilled with clean oil.
4.
It is not advisable to mix oils of different brands or types.
They may not contain required additives or be of com-
parable viscosities. Good grade mineral oils, with viscos-
ities suited to ambient temperatures in which the
machine is operating, are recommended for use.
NOTE:
Metal particles may appear in oil or filters of new machines
due to wear-in of meshing components.
Hydraulic Oil
1.
Refer to Section 1 for viscosity ranges.
Changing Hydraulic Oil
1.
Filter elements must be changed after first 50 hours of
operation and every 300 hours (unless specified other-
wise) thereafter. If it is necessary to change the oil, use
only oils meeting or exceeding specifications in this
manual. If unable to obtain same type of oil supplied
with the machine, consult local supplier for assistance in
selecting the proper equivalent. Do not mix petroleum
and synthetic base oils.
2.
Keep hydraulic oil clean. If oil must be poured from orig-
inal container into another, clean all possible contami-
nants from service container. Always clean filter mesh
element and replace cartridge any time oil is changed.
3.
Inspect all hydraulic components, lines, fittings, etc.
while unit is shut down. Perform a functional check of
each system before placing machine back in service.
Lubrication Specifications
Specified lubricants, as recommended by component manu-
facturers, are always the best choice. However, multi-purpose
greases usually have qualities which meet a variety of single
purpose grease requirements. Should any questions arise
regarding use of greases in maintenance stock, consult your
local supplier for evaluation. Refer to Section 1 for an explana-
tion of lubricant key designations in the Lubrication Chart.
2.4
CYLINDER DRIFT
Theory
When a hydraulic cylinder is supporting a load, cylinder drift
may occur as a result of any of the circumstances below:
• Normal leakage of load holding valves or malfunction of
load holding valves. See Cylinder Leakage Test and
Table 2- 2, Cylinder Drift below for evaluation.
• Damaged or worn piston seals.
• Normal thermal expansion or contraction of the hydraulic
oil within cylinders (See Cylinder Thermal Drift below).
The first two circumstances may result in cylinder movement
due to oil leaking out of the cylinder externally or by leaking
back to tank or due to oil leaking internally from one cylinder
chamber to the other.
Thermal expansion or contraction of oil in hydraulic cylinders
is a normal occurrence and does not result in oil leaking out of
the cylinder or leaking internally from one cylinder chamber
to the other. Thermal expansion or contraction is the tendency
for materials to change size in response to a change in
temperature.
Cylinder Leakage Test
Cylinder oil must be at stabilized ambient temperature
before beginning this test.
Measure drift at cylinder rod with a calibrated dial indicator.
In an area free of obstructions, cylinder must have load
applied and appropriately positioned to detect drift.
Cylinder leakage is acceptable if it passes this test.
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