Final answer:
A moving train is normally brought to a stop by releasing compressed air through the brake valve handle, which applies the brakes through the air brake system invented by George Westinghouse.
Step-by-step explanation:
A moving train is normally brought to a stop by manipulating the brake valve handle so as to cause compressed air to be released.
The air brake system, invented by George Westinghouse in 1869, uses compressed air to apply the brakes on the train. When the brake valve handle is manipulated, it allows the compressed air to escape from the brake cylinders, which applies the brakes and brings the train to a stop.
This invention was a significant improvement over the previous method of manually applying brakes, which was dangerous and less effective.