Which bearing ring has a press (interference) fit on a straight bore bearing?

The correct choice regarding which bearing ring has a press (interference) fit on a straight bore bearing is indeed the small bore bearings.

In the context of bearing design, a straight bore typically refers to the inner ring that fits directly onto a shaft. Small bore bearings are designed to accommodate tighter tolerances and are often fitted onto smaller shafts using an interference fit. This means that the inner diameter of the bearing inner ring is slightly smaller than the outer diameter of the shaft it fits onto, creating a press fit that ensures the bearing remains securely in place during operation.

In contrast, while large bore bearings may also be designed for press fits depending on their application and configuration, they generally refer to bearings with larger inner diameters which might not always necessitate an interference fit due to the nature of their intended use or design parameters. Tapered bore bearings feature a tapered hole that allows for easier installation and adjustment, which does not rely on a standard press fit. Self-aligning bearings are designed to compensate for misalignment, providing a functional characteristic rather than a fit specification related to interference fitting.

Understanding the nature of the fit for small bore bearings is crucial for ensuring proper installation and operation within mechanical systems.