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Bearing
Specification table
is here.
Continue for an overview.
Bearing
Specification - Bearing
Dynamics - Bearing
Geometry. When a bearing is running under load, force is transmitted
from one bearing raceway to the other through the balls. The contact
area between a ball and the bearing raceway (contact ellipse)
may be very small, so that even moderate loads can produce very
large stresses. These stresses can affect bearing performance
and life dramatically, so that it is important to consider the
internal geometry of the bearing before making a selection for
a given application.
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Bearing raceway
curvature ratio (f)
is the ratio of the raceway radius (R)
to the ball diameter (Dw).
Inner
raceway curvature ratio fi = |
Ri |
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Dw |
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where:
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Dw
= ball diameter
Ri
= inner raceway radius
Ro
= outer raceway radius |
Outer raceway
curvature ratio fo = |
Ro |
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Dw |
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fi,
fo
values are typically 0.56 ± 0.03 for small bearings
where low torque is a primary requirement. It is not necessarily
the same for both inner and outer bearing raceways. Raceway
curvature ratio is often referred to as a percentage f
x 100%.
The total curvature of a bearing is
defined as B = fi
+ fo
- 1
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| Bearings are assembled with
a slight amount of looseness between the balls and the raceways.
This allows the bearing to rotate smoothly but also affects the
performance of the bearing in a given application. This looseness
can be split into two components - radial and axial play. |
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is the
maximum displacement that one bearing ring can be displaced
relative to the other ring in a direction perpendicular to the
axis of rotation of the bearing.
Radial
play = ∆r
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,
or end play, is the maximum relative displacement of the bearing
rings, in a direction parallel to the axis of rotation.
Axial
play = ∆a
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Bearing
Radial Play and Bearing Axial Play are interdependent and
are determined during the manufacture of the bearing. Typically,
bearing radial
play is a purchasing specification.
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