WILMERDING, Pa. (WHTM) — It’s been called “the most important safety device ever known.” On April 13, 1869, George Westinghouse received patent 88,929 for the air brake, and railroading became a whole lot safer for both passengers and crew.

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Stopping a train in the early days of railroading was an incredibly dangerous job. Brakemen had to apply the brakes manually to each car in the train, by turning a wheel usually located at the top of the railroad car. As soon as you did one you had to run along the top of the car to the next car, then the next, and the next. Even a planned, controlled stop in perfect weather risked life and limb. As for bad weather, or an emergency stop, well, let’s just say brakeman on a train was one of the deadliest jobs in America.

Westinghouse’s brilliant idea? Make loss of pressure trigger the brakes.

His system, as described in his patent, called for each railroad car to have its tank of pressurized air to close the brakes. A separate pressurized air pipe, running from the engine to the end of the train, held the brakes open. Any loss of pressure in that pipe, from pulling the brake lever or a break in the pipe, would cause the brakes to close.

George Westinghouse, American engineer and inventor, is shown in this undated photo. Westinghouse invented the railway frog, a device allowing trains to cross from one track to another. He also developed the railroad air brake around 1868. (AP Photo)

George Westinghouse started the Westinghouse Air Brake Company to manufacture air brakes, setting up shop in Wilmerding, Pennsylvania, a little southeast of Pittsburgh. (Westinghouse Air Brake Company is now known as Wabtec, after merging with MotivePower Industries, Inc.)

The air brake was adopted quickly, especially for passenger trains (and extra-especially after state and federal governments started passing laws requiring their use.) According to an article on Cambridge.org, “The earliest reliable national statistics show that by 1889, 7,706 of the nation’s 8,079 passenger locomotives (92 percent) and 23,540 of its 25,665 passenger cars (95 percent) were equipped with automatic air brakes.”