Atchison, Topeka and Santa Fe experimental articulated.

A very unusual design for a Mallet-type articulated locomotive. Instead of installing two drivetrains under a long boiler, this was an attempt at making a flexible boiler. In effect it was two boilers with a bellows joining the two parts of the smokebox requiring only a flexible high pressure supply pipe to the high-pressure cylinders. Imagine building a flexible vessel good for 200 lbs pressure while having it move down the track at 45 mph. Cinders getting stuck in the accordion folds caused problems and the engines were soon soon scrapped.

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