how to power a circular rail Carriage

Hello. Looking for ideas on how a circular rail carriage could be powered.

Here is what i am looking at 
http://www.ghbinroth.com/nadella/nadella-multimotion-line-fsr-system.pdf
https://www.alibaba.com/product-detail/High-Quality-And-Precision-Circular-Guide_1974565028.html

On a linear rail its common to use 8mm Acme Lead Screw to translate the nema rotation movement..how is this done on circular carriage like the links above.  thanks

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rickharris1 month ago

The technical term your looking for is Rack and Pinion railway. See image.

rack railway.jpg
iceng1 month ago

If simple transport accuracy a linear stepper motor should do.. A gear race and a worm gear under the carriage..

Thanks a lot )

Circular gear rack.

+1
Or by driving them with a motor mounted in the centre.
Basically like a bike wheel only with he bearings on the outside in your case.