What helps indicate the procedure for applying brakes?

The procedure for applying brakes is indicated by the action of swinging the lamp horizontally above the head. This specific gesture is a visual signal that is recognized within the context of train operations. It conveys a clear message regarding the need to initiate braking actions, allowing those involved in train movements, such as the engineer or conductor, to respond appropriately and promptly.

Using the lamp as a signaling device integrates visual communication into operational procedures, which is crucial in maintaining safety and efficiency on the railway. The practice of visual signals is part of the broader system of train operations, where various methods of communication are employed to ensure precise coordination among crew members in different roles.

The other options, such as raising signals at the control center or sounding the engine whistle, do not specifically relate to the direct procedure for applying brakes within the context of in-train communication or signaling. While they may play roles in various operational contexts, they do not serve the same clear function as the visual cue provided by swinging the lamp, which is specifically focused on signaling braking actions.