What type of brake system is being handled after adding helpers to the rear of a train?

When helpers are added to the rear of a train, the correct brake system being handled is characterized as the service brake system. The service brake system operates through the locomotive's air brake system, which is designed to apply brakes to the locomotive and all cars in the train consist. This ensures that the additional power from the helper locomotives at the rear has coordinated braking capabilities with the rest of the train.

Using the service brake system allows for effective control and management of the train during operations, particularly in situations where traction and braking must be balanced, such as when descending grades or navigating curves. It provides a way to apply braking force evenly throughout the whole train, crucial for maintaining safety and stability.

The independent brake system, while important, primarily controls only the locomotive in terms of braking and is not focused on the entire train's response. The dynamic brake system introduces additional mechanical means of slowing down the train but does not engage the air brakes across the entire train. The hand brake system is usually reserved for securing a train when it is stopped and does not provide the necessary control when helpers are engaged for movement on grades or through complex train maneuvers.