To the uninitiated,
lubrication of gears seems so simple that little
thought need be given to it. However ,
lubricating engineers and most people
concerned with the lubrication of machinery
are well aware of the importance
of proper gear compounds applied in
the correct manner. The producers and many
of the consumers of lubricants realize
that the manufacture and application of
satisfactory gear lubricants involves
considerable knowledge and a lot of
background.
To illustrate this
latter point, one only need cite the
cost and work involved in an
approval test for a single multipurpose
or automotive gear lubricant. Such qualification
work requires about 250 man hours and
is seldom completed in less than 4
to 24 weeks at a cost of
approximately $ 1500. This includes not only bench
tests but also operation of cars on proving
grounds. Such testing has been considered
so important by both the automotive
industry and the U.S. Government that
a large part of the
approval work was delegated to
two of the most prominent Research
Institutes in the United States. More
recently some of the personnel of
these organizations, who were engaged
in lubricant approval testing, have formed
independent companies.
Production figures
for gear and transmission lubricants are
available from surveys made by the
National Lubricating Grease Institute during
the past few years. While thy judge
the assembled figures to be
about 60 per cent accurate for
gear lubricants, even the corrected
figures probably err on the lower side.
Thus, in the case of gear and
transmission lubricants, oils classified
under other headings find their way
into gear boxes. Likewise, lubricating
greases applied to gears
are not designated as such
in tabulation. Also, export and
import proportions of gear oils
are not available. In spite of this,
the figures shown in. Table are
indicative of the volume
of gear oils
used annually
The greatest
proportion of gear and transmission
lubricants are used in automotive and
farm equipment. Noll, ^8 a few years ago,
suggested that passenger cars will average
7 gallons of motor oil per year
and that 4 to 4 ½
Per cent of transmission and
rear axle lubricant ( exclusive of
automatic transmission fluids) to
motor oil gallonage was representative.
However, the present recommendations of
automotive manufacturers are toward longer
service of gear oils, even extending
to the life of the car.
The ambition is to provide sealed cases for such lubricants.
In many instances drain plugs have been eliminated
from gear cases. Such moves, of course, influence
the amount of gear oils used.
This is countered by the constantly
increasing number of vehicles in use.
Since trucks and
buses have larger gear cases
and also account for mileages of
at least ten times that of
passenger cars, such vehicles
may well consume a larger
amount of gear oils than
do automobiles. For example, some truck
axle cases hold 45 pints of
fluid.
Farm equipment and
industrial machinery are also
large consumers of gear
lubricants. Thus, Ford Tractors, series 600 and 800, have
combined capacities of
gear and transmission
cases of 15 to 19 quarts
of fluid. While a considerable amount of
straight mineral oil is used as gear
lubricants, products containing additives predominate. Since
Beard Listed the total extreme
pressure agents used in this
country as 50,000,000 pounds and
stated that the average dosage was
5 to 10 per cent, 7 ½ per cent can
be taken as an average. This then would
account for a total EP
gear oil production of about
660,000,000 pounds, 85,000,000 gallons, or 2,000,000 barrels.
Whatever the total , gear and
transmission lubricants are so
essential for industry and
transportation that they are worthy
of consideration
