In my railroad days with Joshua Lionel Cowen, I had a Lionel steam train - around 1960 model - with locomotive, coal car, couple cattle cars, and a caboose. Also, I could push manual hinge to uncouple cars at a certain spot. It would do steam when liquid smoke ( a special thick mineral oil with certain temperature range) drops down the smoke stack got hot. Earlier trains used pellets down the smoke stack. Internet says Anacin tablet down pellet smoke stack gives some serious smoke!
Circuit shown is of AC motor locomotive (0-20 volts from transformer) and low powered DC motor fan in coal car with resonating chambers to make train whistle sound. Relay in whistle car only responds to DC current. Both power signals are sent down tracks with wheels across rails completing electric circuit.
Digital and computer trains with software is our advanced systems of today.
Much help is available if train electric work interests you. https://www.lionelsupport.com
