American Crane - Prototype Drive Train question.

[chutton01]

I have an older, non-powered Walthers American Crane kit that Walthers may have the parts that maxman mentioned so I can finish building it, so I was looking at various prototype images and videos of the self powered American Crane.  To me, the crane's trucks look like standard freight trucks (my image link above has plain bearings, not even roller bearing), and so I'm wondering what sort of drive the prototype crane had - was it a chain drive of some sort?  I find it hard to imagine a nose-mounted traction motor (such as found on prototype locomotives) working very well with a standard freight truck design).

[WSOR 3801]

 According to the manufacturer, http://www.aolcrane.com/pdfs/dehgeneral.pdf , traction type motor driving inside axle of each truck, triple reduction gearing, cast metal gearcase, and so forth.  

American Ohio Locomotive Crane website: http://www.aolcrane.com/index.html

Also, the work expected is a bit different.  The cranes were expected to move themselves, and maybe a handful of cars, not a regular train.  Often to get to the site, they were lined up in a train, and hauled by a locomotive. 

[chutton01]

WSOR 3801
For some reason, I though American Crane was out of business (sold off or something), not sure why my searching didn't turn up that site, but thank you.