Odd roller-bearing wheelsets

Don't know the manufacturer, but from the cut of the wheels and the way the side frames are mounted to the cross bar they look pretty old, probably dating back to when we all were three-railers -- in the case of these trucks outside third rail.

My immediate thought when looking at that photo, bereft of any research or even "the thought process", was the 0 layout at the 1939-40 World's Fair.  But I think that was two rail;  even so, that might -- or might not -- give you or somebody a starting point.

And of course I could be just plain wrong.

Best, SZ [ wondering which George & Ernie TJ article in MR that was in.....]

Interesting. I think I have some old trucks with similar side frames but not with the split axle feature.

I found these probably-identical truck sideframes in my parts collection, without wheels and axles. The name "Hawk" is visible on the castings. The wheels and axles in the original post might be different manufacture but are presumably similar vintage. I believe the "Hawk" name for model railroad castings goes back into the 1930's.

Could the wheelsets in the original post have been custom-made items for the 1939 World's Fair "Railroads at Work" operating model railroad exhibit? Actually roller bearings??