American Flyer 12B Transformer with reverse switch question

Very interesting. I have never seen the reverse switch on the 12B, but there is one on eBay and it sure looks original. eBay auction number  324237025309

Gilbert probably changed the circuit breaker to a different type and then added the reverse switch. Normally, one would press the circuit breaker button to reverse.

The Gilbert Gallery has closeup pictures of a 12B with the reversing pushbutton. There is no wiring diagram that I have ever found for the 12B. All Gilbert postwar transformers have the circuit breaker between the secondary winding and the base post terminal. Dual transformers have two breakers because there are two secondary windings. Those transformers with reversing switches have them between the winding pickup and the 7V-15V post. The only dual control transformers other than the 12B use a lift up handle. The reversing button on the 12B has to open the circuit between the winding wiper and the 7V-15V post, otherwise pushing the button would also turn off all the accessories connected to the fixed 15V post. Since there are two windings with one button it has to be a double pole switch that would interrupt both outputs.