Boebert@MIT-MULTICS.ARPA (01/29/86)
It should be noted that flanges, on full-scale and large-scale models, do not keep the train on the track during "normal" running; this is done by the physics of a coned wheel riding on arched track. Flanges come into play only on very tight corners and (primarily) while going through switchwork. You can tell when flanges are doing their thing by the squealing of flange against rail.
Dan_Bower%RPI-MTS.Mailnet@MIT-MULTICS.ARPA (01/29/86)
From "Norm"... Lionel flanges... Prototypes always<sic> having flanges on all the wheels... Not so. Ever heard of "blind" axles? On prototype steam locomotives built for sharp curves, center axles were often without flanges, or "blind". Standard guage, "mainline" railroads usually would not have a blind axle on a six-coupled engine, such as a 2-6-2, but invariably would have at least one or two on 8 and 10 coupled engines like 2-8-0's and 2-10-4's. For example, the PRR's first standard, superheated steam Consolidation (2-8-0) engine, the H6sb, had no blind axles. They were rather restricted in the radii of curvature they could negociate. With the H-7 through H-10 engines, the second and third axles were blind, allowing for no degredation in ability to stay on the rail - in fact improving it as they could round the curves the H-6's couldn't. Also, the Pennsy's last attempt at a mainline steam engine, the Q-2 4-4-6-4, had terrible curve tracking abilities because it was not articulated. Even if the 2nd axle of the 2nd engine was blind, it wouldn't have made much difference because of the enormous ridgid frame distance. I've heard stories about those engines where, if the curve was too sharp, it would stay on the rail and move the track, to the great consternation of the track foremen. BTW, to compensate for the overhang on a curve, the tires (yes Virginia, steam engines have tires - of steel. You oughtta see the guy at the gas station try to get one off the rim :-) on blind axles are much wider than the ones on flanged wheels. And center axles were ususally made with the ability to move side to side a bit if they did have flanges.