Who knows the depth of this Hobby? We all have a little niche of what we think is "cool" and I tip my hat to you for your collection of clockwork trains. When you think of the era, all four of your "besties" are remarkable.
The controlled speed John Van Reimsdijk 4-4-4 locos and the Karl Bub Sonderklasse locomotive are beautiful pieces. I am sure finding these units is the epitome of success. Congrats!
