@Miketg- Well someone who likes transformers, Oh Boy! That is neat! I have never had anyone show an interest before, so I thought I might contribute something that I obtained with an old standard gauge set many years ago. Pictured below is a Lionel transformer, designated "Multivolt" and using a stamped steel case which was introduced in 1922. These continued in various models until 1938. The 100 watt, type T, that I am showing was first available in 1923 and continued until the end of the line in 1938.
Here is the top view of the transformer. The voltage delivered to the track depended on two things. Where the swing arm selector was positioned in its motion from left to right and what set of terminals you used to supply the track. For example, if you used terminals C-U (U being neutral or ground) then the voltages available at the moveable selector were 2-4-6-8-10. If you used the highest set of output terminals say A-U then the voltages available would be 17-19-21-23-25

Here is a side view of the stamped steel case. It is about a 3 1/2 " cube and it must weigh 10 lbs!! Note this same transformer, at least from an electrical viewpoint was available with a cast iron case from about 1915. I have a copy of the 1917 Lionel catalog and it is pictured in that publication.

Here is a close up of the "Multivolt" data plate with the designation type T visible in the upper right.

Here is the plug for the mains...my label for this is ..."How to die playing with toy trains"
By the way, the insulation on the wire is the old fashioned fabric type.

So there you are folks, how you got power to the track in the 1920's. In Europe, they made 4 volt motors that could operated on batteries. MUCH SAFER!! I have never plugged this baby in and never intend to...
Best Wishes
Don