Ever see those trucks on the road with a small trailer waay out behind on a long hitch?

 

They look like this:

 

Do you wonder why that little trailer is so far back?  Me too.  So I googled it.

 

The little trailer is called a Pup.  That long hitch is to create extra length.  Length matters.  You can be an 80,000 pound rig on highways, but if your load is heavy and you’re too short, you’ll have too much weight over too small an area.  If you’re carrying something really dense, where you could overload the roads and bridges, by federal regulation you’re limited as to how much you can carry, unless you make yourself much longer than you otherwise need to be to spread the load out over a larger area.  Mystery solved; thank you google.

 

There are other solutions to the weight distribution problem.  Some cement trucks have wheels folded up high.

 

That they can lower when they have a full load and spread the weight out over a larger area.

 

This dump truck has multiple solutions.  There are extra wheels in front of the drive axles that can be lowered.  There is a tax axle in back that can be lowered and locked.