During the visual and mechanical maintenance inspection of rotating machinery, which of the following should be inspected for evidence of rubs, rolling element damage, and lack of lubrication?

The selection of bearings as the correct answer is well-founded due to their critical role in the operation of rotating machinery. Bearings facilitate smooth motion by providing a low-friction interface between moving parts, and they are directly subjected to forces during operation. Consequently, they can easily develop issues such as rubs, which occur when parts that should be separated come into contact due to misalignment or wear.

In addition to rubs, rolling element damage can be a significant concern. This damage may manifest as pitting, spalling, or deformities on the rolling surfaces of the bearings, which can lead to increased friction and ultimately failure if not addressed. Lack of lubrication is another vital consideration; insufficient lubricant can lead to overheating and accelerated wear, severely compromising the bearing's integrity and functionality.

While cooling fans, slip rings, and stator windings also require inspection during maintenance, they do not specifically focus on the direct issues related to rubs, rolling element damage, and lubrication deficiencies that are most pertinent when evaluating bearings in rotating machinery. Thus, the emphasis on bearings in this context is justified, as they are fundamental to ensuring reliable operation and are susceptible to the conditions noted in the question.