bearing. When it has the proper separator, it
is very good for high-speed operation. At low speeds, no bearing separator is required at
intermediate speeds, a ball control separator of steel-ribbon construction is adequate;
while the ultimate high-speed performance is obtained with a race controlled (or piloted),
fully machined separator.
Since balls are assembled into the bearing by eccentric
displacement of the races the number of balls in this type of bearing is limited. More
balls can be introduced into the bearing if a notch is machined into one of the races,
Figure 2(b). Radial load capacity is higher in this bearing than In the standard
deep-groove construction, but high-speed performance and thrust-load capacity Is impaired.
When large thrust loads in one direction are coupled with radial loads, angular contact
ball bearings, Figure 2(c), are usually superior. Most high-speed and precision spindles
use axially preloaded pairs of these bearings. Preload is controlled by the length of the
spacers, which determine axial location of the races, or by mounting the bearings against
one another in a “back-to-back” or “face-to-face” fashion. The
double-row, angular-contact bearing, Figure 2(d), is a simpler arrangement from the
standpoint of the user. The preload
is built into the bearing at the factory.
In contrast to the previously discussed bearings, in which
alignment is a very critical item, the self- aligning ball bearing, Figure 2(e) by virtue
of the spherically ground outer race can tolerate considerable misalignment of shaft and
housing. On the other hand, load-carrying capacity is. reduced due to the high contact
stresses that result from the large difference in curvature between the balls and the
outer race.
The thrust bail bearing, Figure 2(f),
is adaptable to large thrust loads that have almost no radial component. Very large sizes
of this bearing are used in gun turrets and large earth moving machinery.”
Reprinted from “Which Bearing and Why?” by AD. DeHart, ASME Paper 59—MD--i 2, 1959, with the permission of the American Society of Mechanical Engineers, 345 East 17th Street, New York, NY., 10017.
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