---In STMFC@..., <mike_schleigh@...> wrote :
What is it about this particular gear made it so applicable to tank cars? Was it also applied to other cars? I have not looked yet but I do not recall it turning up in other illustrations, drawings, or models of other cars. Why was it a tank car favorite?===================
It wasn't. It was just another of many options the railroad / fleet owner had for equipping their cars. They were likely used just as much under other types of cars, but the distinctive springs are much harder to see under other car types.
One thing to note, starting with the USRA designs of the WWI era, and continuing until at least the 1943 AAR cars, ALL the standard designs incorporated the slotted center sill required for a Cardwell instillation. Therefore, Cardwell draft gear could be fitted to any of these cars, or not; buyer's option. The slots are typically not called out on the general arrangement drawings, but they are there.