Which statement correctly defines the inverse gradient during braking?

Which statement correctly defines the inverse gradient during braking?

• A. Brake pipe pressure is higher at the head end.
• B. Brake pipe pressure is equal throughout.
• C. The gradient exists only when the system is fully charged.
• D. Brake pipe pressure is higher at the rear of the train than at the head end during a service brake.

Answer: (D)

Brake pipe pressure along a train during a service brake changes with distance from the locomotive: the braking signal is generated at the head and propagates back toward the tail, so the head end experiences the pressure drop first while the rear lags behind. An inverse gradient is exactly when the pressure is higher at the rear of the train than at the head end during braking. This pattern reflects the sequential venting of the brake pipe along the train and shows the braking signal moving from the front toward the back. The statement that the brake pipe pressure is higher at the rear during a service brake captures that behavior, making it the correct description. The other options don’t fit this dynamic: pressure is not higher at the head, it isn’t equal throughout during braking, and the gradient isn’t limited to when the system is fully charged.

Brake pipe pressure along a train during a service brake changes with distance from the locomotive: the braking signal is generated at the head and propagates back toward the tail, so the head end experiences the pressure drop first while the rear lags behind. An inverse gradient is exactly when the pressure is higher at the rear of the train than at the head end during braking. This pattern reflects the sequential venting of the brake pipe along the train and shows the braking signal moving from the front toward the back. The statement that the brake pipe pressure is higher at the rear during a service brake captures that behavior, making it the correct description. The other options don’t fit this dynamic: pressure is not higher at the head, it isn’t equal throughout during braking, and the gradient isn’t limited to when the system is fully charged.