What does "cutting in" refer to in locomotive operation?

"Cutting in" refers to the process of activating or integrating a locomotive into a train consist. This involves connecting the locomotive to the train's electrical and air systems, allowing it to take control of propulsion and other functions essential for train operation.

When a locomotive is cut in, it becomes part of the operational command structure of the train, receiving commands from the engineer and effectively participating in the movement. This is crucial for maintaining the efficiency and safety of train operations, especially during changes in the train's configuration, such as adding or removing locomotives to better manage the weight or power needs of the entire consist.

The other options relate to different aspects of locomotive operation. Deactivating a locomotive from a consist, applying brakes, and flagging a railroad crossing involve other operational procedures that are not synonymous with the act of cutting in. Understanding these specific terms helps clarify their distinct roles in train management.