RobS
Super Member
The limiting factor to steam locomotive size, ak power, is the size of the boilers. Once its becomes X size, a longer boiler no longer fits onto locomotives frame and you can still do corners. I believe the #844 was at its max design length. To get more power, the 4014 boiler is indeed longer and its drive trucks were made to shuttle left and right, to accommodate corners. In the photos or movies, you can see the 2 drive trucks on it. But how did they get 300 PSI steam to them?? Which is quite powerful and dangerous to contain. They designed spherical steam joints to the lines on the way to the trucks. These allow the power trucks to move about, as this wonderful machine negotiated corners. Getting this machine to stay on the tracks and have the largest boiler ever on rails, was a design feat. I do love my industrial history..
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