Hey, Helen, I couldn't get your link to work; then I took out a slash after the http. You may want to edit it out, but I'll put the link anyway.
http://www.hvtechnology.com/tractortrailer.html
Those are called semis, around here. I've had two British friends comment on how very large they are, compared to what they have in England.

This link shows what I think of when I think wagon--it's the one labeled Texas buckboard, and the one just below it.
http://www.firstshotphoto.com/carriage.htm

Here's a link showing vans and a mini-van.
http://www.sherrodvans.com/dodge_vans.html

Here's one for panel trucks, thought I'd thought panel meant without windows on the rearward side panels.
http://www.paneltruck.com/

Oh yes--a Bobcat is one brand of front-end loader.