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one small pulley
one big pulley
one belt
one mounting
You could break up the belt into many smaller sections and then join them together to make a chain. It would take long but I think it's the only way to do it. Here is a really good link that shows how to create a chain mechanism.
http://www.youtube.com/watch?v=hfyhi9P9pL0&list=PL9EF04D642F165E8F
I also have it summarised in the word doc if you don't have time to go through all the videos
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How_to_-_Chain_Assembly.docx, 12.4 MB
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To my knowledge, belt cannot be simulated in CATIA. Mostly in IDEAS it may work. Share if you crack it down.