11-30-2016, 08:13 PM
Many of the TM cars, especially the all-steel ones wouldn't have had fishbelly underframes, as the body itself was part of the support structure. Likewise for the single sheathed cars (sometimes erroneously called outside braced). The steel bracing helped to support the car and carry the weight of the lading.
The double sheathed cars mostly represent cars of the '20s (which often lasted well into the '50s), and most of them had an internal framework of steel, too, so a fishbelly underframe wouldn't have been necessary. An exception might be a car with double doors or a door-and-a-half car, where the wider door opening becomes a weak point in the car's structure.
The other exception that might call for a fishbelly underframe is if the railroad ordering the car specified its use - old habits associated with all-wood construction died hard.
Wayne
The double sheathed cars mostly represent cars of the '20s (which often lasted well into the '50s), and most of them had an internal framework of steel, too, so a fishbelly underframe wouldn't have been necessary. An exception might be a car with double doors or a door-and-a-half car, where the wider door opening becomes a weak point in the car's structure.
The other exception that might call for a fishbelly underframe is if the railroad ordering the car specified its use - old habits associated with all-wood construction died hard.
Wayne