Re: 464

To be a little more specific, there is more expansive power in superheated steam. This translates to more horsepower per unit of water boiled. A saturated steam locomotive will start the same size train as an identical superheated one as starting tractive effort is simply a matter of steam pushing against the piston. Once underway, it takes horsepower to bring the train up to speed, this is where superheating comes in as it makes a more-perfect gas from the steam and creates much greater expansive properties.

In order for a superheated locmotive to be efficient, it has to be run with a hot enough fire to heat the steam in the superheater elements and with a sufficient throttle opening to fill the elements with lots of steam. This is why one runs with as much throttle as possible and controls the power output with the reverse gear.

In Knott's case, they would never run 464 hard enough to make the superheater work. I also suspect the elements were bad and needed replacing and/or one of the flue sheets were bad and needed replacing.