Angel is a hard working dog. Before automatic air brakes were common, or still being implemented, trains were stopped using hand brakes located on each car. As a brakemen Angel's job was to climb atop moving railcars—often in dangerous weather—and turn iron wheels to apply or release handbrakes n order to bring it to a stop or control speed on downgrades. In the yards or sidings, she helped couple and uncouple cars, throw switches, and assist with switching operations.
If you're interested in understanding exactly what it is she's doing, here's a snippet from the excellent series "Trains Unlimited" that explains more.
