I designed the following five trains for my son to be able to play with on his wooden train track like Thomas, Brio, etc. I can't remember exactly where (may have been on this forum) but I found that you can turn the small train wheels around and they work good on the wooden track. I tried to design the set as five trains that can be built from one set of pieces. It did save pieces that where repeated between the trains and my son really likes to take apart his lego and rebuild them. I have put instructions for the five trains on my Rebrickable page as well as instructions for each individual train.
The engine for following train is mostly from set 30575. The cargo train includes a coal tender, boxcar, flatbed, and caboose.
The engine for the following train was inspired by set 31054. The logging train includes a coal tender, 2 logging cars, and caboose.
The engine for the following train was inspired by an alternate build of set 31054. The tanker train includes 2 tanker cars and a separate trolley.
This engines front for the following train inspired by the previous engine but I modified it to fit the style of this passenger train. The passenger train includes a baggage car, 2 passenger cars, and observation car.
And the last one was inspired by the crocodile locomotive. The train includes 2 coal cars.
Instructions for all these trains are on the following Rebrickable pages.
https://rebrickable.com/mocs/MOC-90193/bgarms/train-for-wooden-track-5-in-1/#details
https://rebrickable.com/mocs/MOC-88447/bgarms/30575-cargo-train-for-wooden-track/#details
https://rebrickable.com/mocs/MOC-88449/bgarms/logging-train-for-wooden-track/#details
https://rebrickable.com/mocs/MOC-88451/bgarms/tanker-train-and-trolley-for-wooden-track/#details
https://rebrickable.com/mocs/MOC-88452/bgarms/passenger-train-for-wooden-track/#details
https://rebrickable.com/mocs/MOC-88453/bgarms/crocodile-locomotive-train-for-wooden-track/#details