Union Jubilee Clutch.

[Yorkie]

For smaller lathes, you can get heat joinable round section plastic 'transmission belt', which I use on my Lorch. (Just cut to length, heat the ends and hold together till set).

It can be seen on the pulleys on the pic below.

Chronos sell it, and of course a great deal more items for lathes etc:

http://www.chronos.ltd.uk/acatalog/Engin...lt_46.html