[Ukastronomer (Jeremy)]

Originally Posted by bojan

By not loaded I really meant not overloaded...
Of course the belts need to be under certain tension, but for this application ~1N is more than enough.
And the ones pictured can be loaded with more than 100N I am sure
The load imposed by moving the telescope (provided it is balanced) with reasonable acceleration should not be higher than 0.1Nm, so this translates to ~10N.

According to SPD-SI technical data (http://www.sdp-si.com/PDFS/Technical-Section-Timing.pdf, page T62) 5mm wide GT3 belt can be loaded with 11Nm..

BTW, idea is not new.. see here one example:
http://siderealtechnology.com/16Inch...InchScope.html
Or here: http://www.dfmengineering.com/news_t...e_gearing.html

And, my DIY Dob has friction transmission (and no slippage!).. well, not the same thing but still illustrates the issue.