How Do Self-Aligning Bearings Work?

Blog | November 8th, 2017

Self-aligning bearings are viewed with some reverence. After all, this rolling element family has the ability to correct angular misalignment errors on-the-fly. Picture a poorly aligned drive shaft, perhaps one that’s governing a power transmission train. It’s trying to wrench the bearing out of its mount, yet the twin races are adjusting to compensate for the error. Just how do the rings of these self-adjusting bearings work semi-autonomously?

Cracking the Self-Aligning Puzzle 

There’s no engineering wizardry in action here, although the solution sometimes does feel like magic. Inside the bearing, two sets of balls are supported in a cage. That’s a key clue as to what’s taking place inside the device. On the outermost face, a concave surface runs against the double set of rolling elements. If a misalignment incident takes place, the concavity feature shifts the outer ring until the angular error is corrected. Simply put, that curved surface inside the outer race has the ability to pitch and yaw in response to the drive shafts’ eccentric axial momentum. Check out self-aligning bearings in motion. They really do allow the inner ring and twin ball sets to deflect in response to the drive shaft’s angular characteristics while maintaining a stress-free connection with the outer ring and the bearing mount. Again, it’s the intelligently machined concave geometry that facilitates this dynamic function.

Defining Inner Ring Features 

If the arcing race on the exterior ring partners perfectly with the twin ball sets to enable axial yawing, how do the balls retain their own positional attributes? Surely, the balls would fly outward when the thrust stress pull them forward or back. Well, design acuity has taken care of this issue by fitting the inner race with two deeply grooved raceway channels. The caged balls zip down those channels without experiencing the lateral force incurred by the misaligned shaft, so self-aligning congruity is maintained. Employed in instances where shaft-mounted loads have been poorly installed, in situations where exact axial alignment is difficult to achieve, and instances where shaft deflection problems develop over time, self-aligning bearings are rated in degrees and radians. Their angular limitations guarantee stress-compensated functionality in all of the above applications and more.

The unique architectural characteristics of this bearing family are founded on race curvature and dual rolling element guidance. The concave outer race deflects laterally across the ball geometry while the balls slide resolutely inside their raceways on the inner ring. Between these dynamically coupled rings, the two sets of rotating balls act as the ideal bridge, one that perfectly handles the deflection angle, as set by a mismatched drive shaft.

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