FED-STD-791D
11.
Turn rpm counter to "OFF" position.
12.
Push instruments button "OFF".
13.
Turn off main electric switch to test cell.
14.
Turn off main water valve to test cell.
6.2.3 Emergency stop.
1.
Push emergency stop button.
2.
Push instruments button "OFF."
3.
Turn off induction heater power supply.
4.
Turn off main water valve to test cell.
6.3 Inspection and rating.
6.3.1 Scuffed area. The scuffed area of a gear tooth is that area from which
the
axial grinding marks have been removed by scratching, scoring, abrasion, and wear.
As
shown on Figure 7, area A and B are scuffed; area C is not scuffed. Note that only
the
actual working portion (areas A plus B plus C) of the tooth surface is considered in
the
definition of areas.
6.3.2 Percent of tooth area scuffed. The percent of tooth area scuffed is that
portion of the working surface of a gear tooth that has been scuffed.
Referring to Figure 7,
A B
scuffed area * 100
Percentage tooth area scuffed =
=
* 100
A BC
working area
The percent of tooth area scuffed is estimated visually to the nearest 5% for each
individual tooth, with the aid of a net reticule mounted in the eyepiece of the inspection
microscope, or a grid placed over the monitor tube.
6.3.3 Average percent of tooth area scuffed. The average percent of tooth area
scuffed is the algebraic average of the percent of scuffed area of all 28 teeth of the narrow
test gear. Calculate this value to the nearest 1%.
6.3.4 Effective tooth width. The effective tooth width is the actual width of the
narrow-gear tooth that is in contact with the tooth of the wide gear. For test gears
currently available, the percentage effective tooth width may be taken as 98% of the
gross tooth width by means of a micrometer. See 7.1 for calculation.
6.3.5 Load-carrying capacity. The load-carrying capacity of a lubricant is
defined as the gear-tooth load at which the average percent of tooth area scuffed is 22.5%
for the narrow test gear as determined by the method outlined herein.
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