Shaft ends, spindles, collars, and couplings are examples of what type of machine parts?

Shaft ends, spindles, collars, and couplings are all classified as rotating machine parts because they are components that rotate around an axis during the operation of machinery. This classification is important in understanding the dynamics of machinery and ensuring safety practices are adhered to when working with or around these components.

Rotating machine parts can pose specific hazards, such as entanglement, which is why it's critical for workers to recognize them and apply appropriate safety measures. Employees should be trained to maintain a safe distance from these parts when they are in motion, understand the importance of guards and barriers, and wear proper personal protective equipment (PPE) to prevent accidents.

While the other options refer to different types of machine motions or hazards, the specific nature of shaft ends, spindles, collars, and couplings aligns clearly with the designated category of rotating machine parts, highlighting the need for specialized safety training related to these components.