I think there's a typo somewhere:
"The engine is a 2-4-2 radial tank, the diameter of the coupled wheels being 5 ft. 8 in. and of the radial wheels 3 ft. 7 in. Cylinders are 174 in. diam. and 26 in. stroke: boiler pressure is 180 lb. per square inch; length over buffers, 37 ft. 2 in."