Im pretty sure there is an old (b&w) documentary video that covers that quickly (like two seconds); Marx, Lionel? No telling, I watch the Euro videos too....And I was told as a kid, an original steam bearing lasted longer than a replacement from not having to be pressed over the raised splines...???? I was also sent on snipe hunts at, so you never can tell 
My grandfather had blank axles, and I know he had a spline, press similar to a pipe flairing block press. It came in handy on resetting some loose Marx wheels though the pattern was off. He had arbors for the flat pressed onto car axles too. Bought or made?; its tough to say.
