TM 5-3895-359-14&P
3. Research has developed a number of additive
3. Normally these pumps require no manual
agents which materially improve various characteristics
priming. It is essential, however, that after starting a
of oils for hydraulic systems. They may be selected for
minimum drive speed of 400 rpm be maintained until
compounding with a view toward reducing wear,
the pump picks up its prime. Failure to observe this
increasing chemical stability, inhibiting corrosion,
precaution can result in scoring and possible seizure of
depressing pour point and improving the anti-foam
the pump due to a lack of oil for lubrication.
characteristics. Proper use of additive agents requires
4. An integral relief valve protects the hydraulic
specialized knowledge, and they should be incorporated
system components by limiting the maximum pressure.
by the oil manufacturer only, as serious trouble may
5. Relief valve sub-assemblies are pre-set and
otherwise result.
tested by Vickers for given pressure settings.
4. Most oil companies have several brands of
6. Operation in excess of 180F.
results in
crankcase oils of somewhat varying formulation that will
increased wear of the system components and causes
meet the API service classification of MS. The more
more rapid deterioration of the oil. The hydraulic
desirable of these oils for hydraulic service will contain
system that is designed to maintain a temperature of
higher amounts of the type of compounding that avoids
160F. or less is desirable.
scuffing and wear of cam lobes and valve lifters. These
oils will also be formulated to be stable under oxidative
HYDRAULIC FLUID RECOMMENDATIONS
conditions and when in contact with small amounts of
moisture. There should also be reasonable protection
NOTE: Do not use hydraulic brake fluid. Use only high
against rust to any ferrous materials submerged in the
grade hydraulic oil of the viscosities recommended in
oil or covered by the oil's film.
paragraph D of Hydraulic Fluid Recommendations. Do
5. Table I summarizes the oil types (viscosity and
not use fire resistant fluids in Vickers' products without
service classification) that are recommended for use
consulting Vickers'
Mobile Division application
with Vickers equipment.
This selection is most
engineering personnel. "0" rings, seals and packings
important and should be made with considerable care.
which are compatible with petroleum base fluids are not
compatible with synthetic type fluids.
TABLE I.
1. Oils used in hydraulic systems perform the dual
function of lubrication and transmission of power. Oil
Hydraulic System
SAE
API Service
must be selected with care and with the assistance of a
Operating Range
Viscosity
Classification
reputable supplier. Use of an improper grade of oil may
(Min. to Max.)
result in inlet vacuum conditions exceeding the
0 F. to 180F.
10W
MS
recommended maximum 5 inches of mercury, and will
15F. to 210F.
20-20W
MS
reduce the life expectancy of the hydraulic equipment.
32F. to 230F.
30
MS
Where vacuum exceeds 5 inches of mercury, and it is
0F. to 210F.
10W-30
MS
not caused by improper oil selection, the Vickers Mobile
Hydraulic
Division
is
to
be
consulted
for
6. These temperature ranges for each grade of oil
recommendations.
are satisfactory if suitable procedures are followed for
2. Crankcase oils meeting or exceeding the "Five
low temperature start-up conditions and if sustained
Engine Test Sequence" for evaluating oils for API
operation is avoided at the upper temperature limits.
(American Petroleum Institute) service MS (Maximum
For optimum operation, a maximum oil viscosity of 4000
Severity) best serve the needs of mobile hydraulic
SSU at the low temperature start-up condition and a
systems. These engine sequence tests were adopted by
minimum oil viscosity of 60 SSU for the sustained high
the Society of Automotive Engineers, American Society
temperature operating condition are recommended.
for Testing Materials, and automotive engine builders.
Operation of the fluid at temperatures below 160F. is
The MS classification is the key to selection of oils
recommended to obtain the maximum unit and fluid life.
containing the type of compounding that will extend the
7. Automatic Transmission Fluid, Type "A" is
operating life of the hydraulic system. Oils meeting
usually satisfactory for power steering systems or those
Diesel engine requirements, DG and DS classifications,
systems operating under moderate hydraulic service.
may or may not have the type of compounding desired
for high performance hydraulic systems.
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