My LHS stocks P2K HO wheelsets in both 33" and 36" . Is one appropriate for freight and another for passenger cars, or is there another consideration. Three scale inches isn’t much and I doubt most people could tell the difference with the naked eye. From a model standpoint, does one size have advantages over the other or is this just a matter of preference.
Typically for steam era, 33" for freight and 36" for passenger. For more modern cars, some 100 ton freight cars have 36" wheels, some have 33" or other sizes
Indeed there is very little difference to the naked eye. The difference is that a passenger car equipped with 33" wheels will take a lot of shimming to match coupler heights.
A freight car with 36" wheels will give high coupler heights.
Dave
Traditional ‘Transition Era’ rolling stock normally uses 36" wheels for passenger cars and 33" wheels for freight cars. The ‘real’ factor is weight. Most loaded freight cars of the era weighed less that 75 tons fully loaded. A passenger car could weigh 80 tons or more. The thickness of the axle bearing and the ‘contact patch’ with the rail is the deciding factor. A 36" wheel has a larger ‘contact patch’ and spreaded the weight out on the rail head - Not a lot, but when all of that weight is pointed at a small spot, it makes a difference.
Current freight cars usually have wheels based on the following:
- Up to 77 tons - 33" wheels
- Up to 140 tons - 36" wheels
- Over 140 tons - 38" wheels
Various railroads have different standards, but the above numbers are typical,
Jim