Hello Everyone:

I study infant learning and I am reaching out for help in recreating a train set from research done 20+ years ago. 

Essentially an HO-scale train consisting of an engine and three brightly colored railcars went around a circular track (47.5 cm diameter).  I am trying to find HO-scale engine and railcars that are small enough in length that they can seamlessly go in a circle with such a small diameter.  I am having a hard time finding out the dimensions of engines and cars included in sets, etc.

Any help would be greatly appreciated!  Thank you for your time.

I have included links to 2 image below but if you use google images "operant train task" you can find more.


Pic1
https://drive.google.com/file/d/1MzxjsaxCSutxbSQe0f83jm5POIy75tAb/view?usp=sharing

Pic2
https://drive.google.com/file/d/18SOeIKmGDqgS9dvr6rEm75KK3IZLWwiv/view?usp=sharing