Simple Train for Infant Research Study

[BabyScientist]

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

[Len]

47.5cm diameter would be a bit more than 18" in diameter, or 9" radius. That would be hard to duplicate using sectional HO track, which generally has a minimum radius of 15", or 30" diameter.

On average, and most adults are somewhere near 18" across the shoulders. So, looking at the pictures, the circle of track appears to be larger than an 18" diameter. Some years ago, there were a few 'toy' HO sets that came with a 24" diameter circle of track. But they've pretty much disappeared from the market.

I would suggest using a 15" radius/30" diameter circle of track. Pretty much any 4-wheel diesel loco and 36 or 40 scale foot freight cars should work just fine.

Len

[Terry Toenges]

In looking at Pic 1 - A bobber caboose is about 3" long. The other cars look to be about the same so that is 9". The loco is about 3 3/4" long. That would be 12 3/4". If you were to straighten the train out across the diameter, you could maybe fit two more 3" cars. If that was the case, that would be 18 3/4" diameter. Just a guesstimate..

[jward]

The locomotive in both photos is a Docksider. These were made by many companies over the years.

The caboose is a bobber, either Mantua/Tyco or Bachmann.

The two cars in the bottom photo are ore cars made by MDC/Roundhouse. Currently, they are sold by Athearn.

The gondola in the top photo is a mystery to me but appears to represent a car from the 1800s. Tyco and Bachmann have made similar cars, possibly this one is AHM/Rivarossi?

Alternately, you could use the locomotives and cars from Bachmann's Thomas line. They are British prototype, but they have the advantage of a well known TV series so the characters should be familar to small children. These locomotives and cars are very short compared to their American counterparts, and might work on such a small radius curve.

It looks to me like the train in the photos is running either on a 15" radius curve, or the 14" radius track used in Europe.

[Len]

18" or 24" diameter, compared to 20 years ago, finding HO track that tight today will not be easy. That's why I'd suggest just going with a 15" radius/30" diameter circle with track that's easy to obtain today. I don't think the track diameter is actually all that important to what the experiment is trying to do. It was probably what was handy at the time.

Len

[BabyScientist]

Thank you all for your input!  I have definitely learned a lot these past few weeks.

I have the original train box with lever (as seen in the pictures) and I verified the measurement. The diameter (as measured from the interior portions of the circle/track) is 18.7 inches (47.5 cm), making the radius 9.35 inches.  I have also verified that the gauge of the tracks is standard HO size.

Is there any sort of resource that states which HO-scale locomotives, cars, caboose, etc. handle tighter radii better than others?  I've been searching online; I found this youtube video https://www.youtube.com/watch?v=JKGaw3Wfamw of a minimum radius test track, but I went to the website and emailed them to see if there was a spreadsheet with testing information, with no luck.  Essentially I am looking for cars/locomotives that aren't too long, but any other suggestions of what to avoid or try are welcome.  Is there a resource that compares the length of different cars/locomotives/etc.?

I will definitely look into the leads here about which potential trains were used in these photos from 20 years+ ago.  We are aiming to use the same parameters as already be used in research--so that is the challenge that we are working with.  It might just involve a lot of trial and error in determining what will work for our purposes!

I really appreciate you all taking time to read and share your ideas!

[Len]

You'll probably have to use flex-track to get a circle that tight these days.

For a train that will do curves that tight, I would go with one of the 4-wheel locomotives in Bachmann's 'Thomas' line, either Percy, Ben or Bill. Any of the 4-wheel 'Thomas' freight cars should work. They can be painted if you need colors other than those available from the factory.

Len

[bbmiroku]

Some companies offer Streetcar track that comes in tiny-radius (6-9") dimensions.  You might want to look into that if this is still a problem for you.