Checking a Model Vehicle's Scale

Toystate CAT 797F compared to HO scale.

Several years ago I acquired this CAT 797F manufactured by Toystate.  This diecast model is sold in a package that does not indicate scale, however a majority of the eBay listings I browsed indicated it was 1:101 scale.  You can find these models on eBay or on Amazon here.

Read along as I show you how to compare a vehicle like this to the scale you model.  In this case, 1:87 (HO) scale, or 3.5mm to the foot.

There are quite a few well done scale rulers, I'd recommend Excel scale rulers if you're going to purchase one.  As you'll see in the article, I chose to use a downloaded, printable one.  You can find a similar one at this link:

To begin, we have to find out the prototype's actual measurements, I simply searched "CAT 797F measurements."  The Wikipedia page is a reliable enough source for this data, and indicates that the 797F is 49' 6" long, and 31' 3" wide over the tires.

Scale ruler indicates the model is only 42' 6" long.

Wheel width tops out at a scale 25'

These two measurements tell us that the model is in fact under-scale for HO scale.  I reason to believe that the estimate of 1:101 scale is correct.

For HO scale modelers, this truck is under sized, but is a good representation of the massive size of these mining trucks, and in my case will do just fine to represent them on my future layout.  I liked this model so much that I recently bought another on eBay!  As long as I don't park the truck directly next to another like sized vehicle, I feel the scale discrepancy will be OK.

Check out these photos of the CAT 797F next to a Greenville two bay hopper on my photo track.

Here's a photo of the model alone, so you can get a sense for the detail included on it.  I'd consider this a diecast toy that can be used for good stand in until you can afford a Classic Construction Models brass version (we're talking $1000 for those).

As with any model like this, there's certain risk involved in buying a model that is not marketed at HO scale or 1:87 scale, however, with some decent experimentation, one can find great models that will work for you, without breaking your budget.

As for the ruler, you can buy a nice metal one, or print your own like I have here.  I printed mine to "actual size" to keep my printer from distorting the measurements.  The actual ruler I show here has been edited, because the URL printed on it poses a security risk, and no longer contains the model railroad downloads.

©2020, Josh Baakko,