Which rolling element bearing had no inner ring?

The rolling element bearing that is characterized by having no inner ring is the needle bearing. Needle bearings utilize elongated cylindrical rolling elements, which are known as needles, and these are supported directly by the housing or the shaft on which they operate.

This design allows needle bearings to provide a very low profile and high load-carrying capacity, making them particularly useful in applications with limited space. In the absence of an inner ring, the shaft itself acts as the raceway, which can contribute to weight savings and space efficiency in machinery applications.

In contrast, other types of rolling element bearings, such as ball, spherical roller, and tapered roller bearings, generally involve both an inner and outer ring. These rings serve as raceways for the rolling elements, creating a more traditional bearing assembly that can help manage misalignment and load distribution effectively.