Which specialized device indicates a brake pipe pressure decrease to show that brakes are applied?

The end-of-train telemetry device (ETD) is specifically designed to monitor and relay information about the brake system, including brake pipe pressure. When there is a decrease in brake pipe pressure, it signifies that the brakes are being applied. This device communicates this critical information back to the locomotive, allowing the engineer to be aware of the braking status of the entire train.

The ETD is vital for ensuring safety and operational efficiency, especially in long trains where the engineer cannot visually inspect the rear cars. The telemetry system provides real-time monitoring and alerts the crew to any issues related to the braking system.

Understanding the function of the ETD helps in grasping its role in the overall braking system and emphasizes the importance of brake pressure monitoring from the rear of the train, enhancing safety during operations.