Mention of
some of the demands made on gear
and transmission lubricants may well
serve as a further justification for
the assembly and publication of
the information to follow. Reviewing the problems
confronting the automotive industry, Raymond^9 considers the
hypoid axle to be the hardest
working and perhaps the most
neglected automotive component. It is said
to be far easier to deliver increased
horsepower and torque to a rear
axle than to build satisfactory
durability into such a critical unit
which is confined by size and
weight limitations. Since higher engine
horsepower and automatic transmissions have
greatly increased low gear loading
and higher pinion offset has produced
more sliding motion between gears,
Raymond^9 con- clues: Lubricants thus
have become a limiting factor
in the load carrying capacity of
American axles.
Automatic
transmission fluids offer another challenge
to the oil industry in that a
complex combination of requirements exists
for such fluids, and Raymond^9 believes
that the future appears to offer a
still greater challenge in severity of
automotive transmission operation.
In addition
there is a tendency for the use
of a single gear oil to per
from several functions. For example , a lubricant
may be called upon not only to
protect bearings and gears against wear and
corrosion, but also to act as a
hydraulic medium. Likewise, an automatic transmission
fluid, the primary purpose of which is
that of a torque converter, may also be
called upon to lubricate hypoid axles in
the future.
The severe
conditions under which some gear oils
operate is stressed by Hundere^5
who states: “ The most difficult function
that a gear lubricant must
perform is that of preventing excessive
metal to metal contact in the region
of maximum sliding velocity. When it
is realized that the unit loading
at the point of contact is as
high as 400,000 psi and the sliding
velocity is as high as 6,000
fpm, it is amazing that excessive
wear, let alone fusion, can be avoided.’’
It is
quite evident from the above that
constant improvement in qualities of
gear lubricants is necessary to meet
changing demands. In spite of the upgrading
of such products, they are universally
available at reasonable costs. It is well
to keep in mind that, from an
economic standpoint, the benefits of
correct lubrication, including that of gear
sets, are mainly due to reduction
in breakdown or maintenance and
consequent decrease in loss due
to downtime or curtailed production.
This holds true for both transportation
and manufacture. Saving s in power and
frictional energy, while often
attributed to correct lubrication, are
small compared with the first
benefits mentioned.
