My mechanical knowledge / ability is very limited so bear with me.

I want to built a small platform (for a robot) supported by three wheels. I need shafts A, B & C, able to rotate in any sense with no limitations.

http://i1000.photobucket.com/albums/...ari/shafts.jpg

Can anyone suggest a simple scheme showing what kind of bearings / bushes do I need thinking of a light platform, no more than 1,5 Kg batteries and electronics included?

As a reference, the platform is of square shape, 30 x 30 cm, aluminium maybe 4mm thick.

In the future each wheel will have its own motor / battery and slip rings to receive the on/off commands.

Would anyone be so kind to show a basic scheme to help me to realize how it should / could be?

By the way, is it correct to call them "multi turn"?