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Out of all the engines on the iron road, BigBoy had the largest FireBox of all. It was 22 feet long! Temperatures inside the FireBox got as hot as 1500°F! The top part of the FireBox was called the Crown Sheet. It was the hottest part of the FireBox, most steam was produced there. It had to continuously be surrounded by water, otherwise, it would get so hot that the entire structure would melt, causing catastrophic boiler failure resulting in a boiler explosion.

Grate Area: 150.3 sq. ft.