The Navy Gear Wear Tester is
described in Federal Methods 791, Methods 335. The equipment
makes use of
small brass and steel
gears, but Ninos
has also used
mating gears of other metals, such as
brass on stainless steel, Phosphor Bronze, and
ST Aluminum on SAE
4130 steel and SAE B-1112
steel against stainless
steel.
In the
test two helical
gears of dissimilar
metals, each approximately one half inch
in diameter are rotated
together as the driving
motor delivers a simple harmonic motion of 4.0
inches amplitude and 40
cycles per minute, through a crack to
the upper brass gear. This gear oscillates
approximately one revolution while a torque load of about three
and one half inch pounds is applied to
the test gears by
means of a seven pound
weight. The gears are
oscillated for the desired
number of cycles, or until gear tooth
failure due to
excessive wear occurs. At the completion of the test, the
gears are removed from the fixture, cleaned as before, and reweighed to determine weight loss. The wear rate in mg
for 10,000 cycles is then calculated permitting a comparison of different
lubricants. New test gears
are used for
each run even though
there is virtually
no wear of the steel
gear as compared
to the brass gear.
Both fluid products and
lubricating greases can be tested as gear lubricants on this apparatus.
Indications are that
with increase in viscosity
of gear oils
the gear wear decreases. No speculations are given
as to how much of
the wear might
be due to abrasion which is due
to particles from the gears.
