Try setting it up as a figure.  When you have all the parts properly
parented in the scene (and nothing else except the GROUND),,,
open the hierarchy window, select the topmost item and hit the
"Create Figure" button.  This will give you a complete figure in
the New Figures library section.

You'll need to make one manual edit in the resulting CR2:
find the wheel and change

bend 1

to

bend 0

After that, you'll need to load the figure and use the Joint Editor (alt-W-J)
to put the center of the wheel (green cross) into its true center, because
the Create Figure will most likely put the center of the wheel at the top. 
Resave, and you should then have a fully usable barrow figure.

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