ACFX 4 truck tank cars - NALCO National Chemical Company

[Mark5]

From the angles in various photos, the "inner" pair of trucks do not appear to be load bearing - if that's true, then what's the purpose of the extra trucks? 

https://www.railcarphotos.com/PhotoDetails.php?PhotoID=67260

another view:

https://tinyurl.com/4y4a4sc2

Mark (looking for enlightenment )

[Point353]

Yet another view: http://ac60w.rrpicturearchives.net/showPicture.aspx?id=6327475

[samusi01]

I'm at a loss... perhaps my brain cell didn't load the sarcasm detection module on boot this morning. How could the inner trucks not be load bearing?

[CR4100]

There is a span bolster that distributes weight to both trucks. The tank car body is supported by a connection to the span bolster between each of the trucks.

Edit: In the original picture you can see the open space above each of the trucks.

See my crude drawing here:

[Mark5]

Yes, that photo link that Point353 posted led me to that conclusion - thanks! (I saw the light!)