Hi Dave,
1. The axles do not have shoulders. That way we could avoid having to fit the leading edge of the axle seat in the wheel bore to accommodate a fillet which would be required for such a shoulder.
2, 3. The wheels were gauged using go/no go gauges against the insides of the hubs, after we verified the dimension from those hub faces to the back side of the flange. Design gauge is based on back gauge and check gauge. We have always very carefully maintained minimum check gauge on switches and maximum check gauge on wheelsets.
These wheels are “narrow flange contour” which calls for a slightly wider back gauge in order to maintain an appropriate check gauge. The original Maine two foot railroads invariably used narrow flange contour wheels. In the preservation era, several wheelsets were made using modern wide flange contour wheels, but pressed to a back gauge intended for narrow flanges. Those wheelsets have proven to wear out very prematurely (thin, sharp flanges).
These new wheelsets we have designed have very appropriate contact from flange to rail.
Thanks,
Jason