FIT Phase 1 Practice Exam

Changing the makeup of a locomotive consist in the middle affects the brake system’s continuity. The air brake setup relies on a brake pipe that runs through the consist via MU hoses between locomotives, and proper operation depends on the pipe being charged and free of leaks with all units responding in concert. When you add or remove units in the middle, those connections can be disrupted, potentially creating leaks or uneven brake response across the train.

A locomotive air brake test checks that the brake pipe is charged to the correct pressure, verifies there are no leaks on the modified portion, and confirms that both the locomotives’ independent braking and the automatic braking commands propagate properly to every unit. This ensures a safe, uniform brake application and release for the entire consist after the change.

It isn’t dependent on train length, and it isn’t limited to passenger service—any time locomotives are added or removed from the middle, the test is required.