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National Advisory Committee for Aeronautics, Report - Comparison of Performance of Experimental and Conventional Cage Designs and Materials for 75 Millimeter More Cylindrical Roller Bearings at High Speeds

The results of two investigations, one to determine the relative
merits of four experimental and two conventional design ’75-
millimeter-bore (size 215) cylindrical roller bearings and one
to determine the relative merits of nodular iron and bronze as
cage materials for this size and type of bearing, are reported
herein. Nine test bearings were operated over a range of DN
values (product of bearing bore in mm and shaft speed in rpm)
from 0.3X10" to 3.3X10‘, radial loadsfrom 7 to 1613 pounds,
and oil flows from 2 to 8 pounds per minute with a single-jet
circulatory oil feed.

0f the size bearings used to evaluate designs, four were eaperi~
mental types with outer—race—riding cages and inner-race-
guided rollers, and two were conventional types, one with outer~
race-guided rollers and cage and one with inner—race—guided
rollers and cage. Each of these six test bearings was equipped
with a difierent design cage made of nodular iron.

The experimental combination of an moter-race—n'ding cage
with a straight-through outer race and inner-race—guided rollers
was found to give the best over-all performance based on limiting
DN values and bearing temperatures. The better performance
of this type bearing over both the conventional inner-race-riding
cage type and the conventional outer-race—n'ding cage type with
outer-race-guided rollers is a result of the relative ease of lubrica—
tion and cooling and of the adequate oil exiting paths which
minimize oil entrapment and churning losses.

The conventional inner-race-riding cage-type bearing could
not be successfully operated at DN values above 1.72X10" be-
cause it is inherently dizficult to lubricate and cool. For the same
reason, the operating temperatures of this type bearing were
higher than those of the four experimental bearings throughout
the range of speed and oil flow investigated.

The conventional outer—race-riding cage-type bearing with
outer-race—guided rollers operated successfully at a DN value
of 2.1 X] 0’ but incurred very severe cage and roller wear at very
high speeds, probably because of high cage slip. This type
. bearing was found to be adequately lubricated and cooled at
relatively low oil flows (2.0 and 2.75 lb/min). At oil flows of
5.5 and 8.0 pounds per minute, however, this type bearing
operated at higher temperatures than the other test bearings
because of excessive churning losses.