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raceway profile 1
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MikeHalloran
Mechanical
The external dimensions for bearings are pretty well standardized.
The internal dimensions are not, and may be regarded as proprietary by each of the multitude of manufacturers.
A radius gage may not tell you all there is to know,
- because it's a relatively imprecise tool,
- and the geometry of the race section may not be exactly circular.
Example: Kaydon 'X' ball bearings have ogival grooves, making them sort of equivalent to a pair of angular contact bearings, because that's how they are used; in a single installation to resist radial loads, axial loads, and moments produced by overhung radial loads.
I think the relatively large groove radius you report is intended to make the bearing relatively insensitive to misalignment, but that of course interacts with the actual major/minor diameter of the grooves and the ball size and the parallelism of the groove center to the bearing faces.
... and I am guessing, too. I know less than what you can find in the 'engineering' section of any bearing maker's thickest catalog.
Mike Halloran
Pembroke Pines, FL, USA
The internal dimensions are not, and may be regarded as proprietary by each of the multitude of manufacturers.
A radius gage may not tell you all there is to know,
- because it's a relatively imprecise tool,
- and the geometry of the race section may not be exactly circular.
Example: Kaydon 'X' ball bearings have ogival grooves, making them sort of equivalent to a pair of angular contact bearings, because that's how they are used; in a single installation to resist radial loads, axial loads, and moments produced by overhung radial loads.
I think the relatively large groove radius you report is intended to make the bearing relatively insensitive to misalignment, but that of course interacts with the actual major/minor diameter of the grooves and the ball size and the parallelism of the groove center to the bearing faces.
... and I am guessing, too. I know less than what you can find in the 'engineering' section of any bearing maker's thickest catalog.
Mike Halloran
Pembroke Pines, FL, USA
The race surface cross section profile of ball bearings have a radius slightly larger than the mating balls. The term for this is osculation, and the race profile radius is usually defined as a percentage of the ball diameter. Most radial ball bearings use a race profile radius equal to somewhere between 0.52D and 0.55D (D = ball diameter). The inner and outer races typically use slightly different osculation ratios to balance fatigue life and efficiency. In general, there is a trade-off between efficiency and load capacity with osculation ratio of ball bearing races. A lower osculation ratio like 0.52 (ie. a more conformal contact) will give better load capacity, while a higher osculation ratio like 0.55 (ie. a less conformal contact) will give better efficiency.
The bearing described in the OP seems a bit unusual. There are single row self-aligning ball bearings, but they would typically have a much larger outer race profile radius than what the OP describes. The drawback of self-aligning ball bearings is that they have very limited load capacity, so it is more common to see two row self-aligning ball bearings.
The bearing described in the OP seems a bit unusual. There are single row self-aligning ball bearings, but they would typically have a much larger outer race profile radius than what the OP describes. The drawback of self-aligning ball bearings is that they have very limited load capacity, so it is more common to see two row self-aligning ball bearings.
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