A few days ago there was a discussion about the purpose of ribbed back wheels, and the answer was the "ribs" were there for cooling during forming - casting of the iron wheels. But, when did we see ribbed-backed wheels disappear from the rails? Apparently the "ribs" went away with the use of steel in wheel making.
So, what time period is proper for using ribbed-back wheels? Was there some RR "rule" condemning them?
