What is the primary feature of a double row angular contact bearing?

The primary feature of a double row angular contact bearing is its ability to handle axial loads from both directions. This is achieved due to its design, which consists of two rows of rolling elements that are positioned at an angle to the bearing axis. The geometry allows the bearing to accommodate axial loads acting on both sides, making it especially useful in applications where there are directional loads, such as in machine tool spindles or gearboxes.

While the other options may contain some truths, they don't align with the fundamental characteristics of double row angular contact bearings. For instance, they can indeed handle radial loads, which is a critical function of these bearings. They are not limited to high-speed applications only; while suitable for such uses, they also operate effectively under various speeds depending on other design features. The inner diameter size does not define the primary function of the bearing but rather affects its fit in different assemblies. Thus, the capability of managing axial loads from both directions distinctly sets double row angular contact bearings apart.