Etnyre Black-Topper, Эксплуатация Обслуживание Безопасность

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Maintenance
Hydraulic Fluid Requirements
General Information
The ability of a hydrostatic transmission to
maintain desired performance for the expected life
depends on the quality of fluid being circulated in
the units. Fluid quality can be measured in three
generalcategories: lubricity, contaminants, and
temperature. Obtaining satisfactory values in these
three areas depends on the fluid and the circuit in
which it is used.
Etnyre field service experience indicates that most
transmission failures result from a breakdown
of fluid quality. Primary causes are solid particle
contamination and overheating. Water or oil in
the fluids are also significant contributors. These
problems are usually the result of poor maintenance.
Sometimes fluid selection can lessen the impact of
unusual environmental factors.
Hydraulic Fluid Requirements
The catalog ratings and performance data are
based on operating with good quality petroleum
based fluids. Premium hydraulic fluids containing
high quality rust, oxidation and foam inhibitors
are required. These include premium turbine oils,
API CD engine oils per SAE J183, M2C33F or
G automatic transmission fluid (Type F), power
shift transmission fluids meeting Allison© C-3 or
Caterpillar© TO-2, and certain specialty agricultural
tractor fluids.
Although fluids containing anti-wear additives are
not necessary for satisfactory performance, when
used, the fluids must possess good thermal and
hydrolytic stability to prevent wear, erosion and
corrosion of the internal components.
Where water contamination is likely due to
condensation, operation in a damp environment
or frequent splashing, a fluid with outstanding
hydrolytic stability is recommended. Consult the
Etnyre Service Department for recommendations
for these fluids. Avoiding the use of Dexron© II
transmission fluids which
do not
meet Allison C-3
specification is recommended.
Viscosity & Temperature
Requirements
The fluid must have sufficient viscosity to maintain
an oil film at the bearing surfaces. This depends
on fluid selection and on operating temperature.
Recommended viscosity for best life and efficiency,
and minimum for intermittent and continuous
operation is listed below.
Fluid Viscosity Limits For
Petroleum Based Fluids
Maximum Continuous SUS (cSt) 500 (110)
Optimum Viscosity SUS (cSt)
70 (13)
Minimum Continuous SUS (cSt) 55 (9.0)
Minimum Intermittent SUS (cSt) 47 (6.4)
Viscosity index improved (multi-viscosity) fluids
may noticeably shear down in service when used
in hydrostatic transmissions. This will lower the
operating viscosity below the originally specified
value. The lowest expected viscosity must be used
when selecting fluids. Consult your fluid supplier
for details on viscosity sheardown.
Fluid temperature affects the viscosity of the fluid
and resulting lubricity and film thickness. High
temperatures can also limit seal life, as most
nonmetallic seals are adversely affected by use
at elevated temperatures. Also, fluids may break
down or oxidize at high temperatures, reducing
their lubricity and the resulting life of the unit.
Cavitation is more likely at high temperature.
Recommended limits for operating temperatures
are tabulated below.
Fluid Temperature Limits For
Petroleum Based Fluids
Continuous Limit 180ºF
Intermittent Limit 220ºF
These temperature limits apply at the hottest point
in the transmission, which is normally the motor
case drain.
Heat problems sometimes occur because of
problems with one of the circuit components.
A partially stuck relief valve will heat up the oil
rapidly. Circuit components that have developed
high internal leakage rates will contribute to heat
generation.