There is, however, an additional step some cities are taking to superheat sludge and convert it into small pelletized granules that are high in nitrogen and other organic materials.
In 1929, it was decided to not to superheat any more slide valve engines and those so fitted reverted to saturated steam as boiler renewals became necessary.
There was also an additional level of superheat between the high- and low-pressure cylinders, allowing the loco to achieve a tractive effort of 83700 lb.
