I'm having a hard time understanding how the joints are done in this model:

http://sketchup.google.com/3dwarehouse/details?mid=9781db44559b41863c22fd316df819f&prevstart=0

I can't seem to locate the joints to see their properties or to even see what kind they are. I've exploded the view and can't find them. I'm especially interested in the front wheel, as it seems to pivot from side to side while also rolling...something i've tried to recreate for some time.

Can someone show me how they did the joints in this model? or atleast explain how to replicate that front wheel.

Thank you so Much!

Joe