norwest cheers arrowsmith-2 flows ..., page-75

Thanks Janus, TU from me...

I can't figure it out either. Especially for the short radius turns.

Just found a couple of videos

http://www.youtube.com/watch?v=AYQcSz27Xp8

Doesn't really explain how it turns though it does appear that drill bit turns on the end of a stationary shaft. I alway assumed the whole shaft had to turn. So I presume the motor that drives it is part of the drill bit assembly.

And another one on the fraccing process.

http://www.youtube.com/watch?v=73mv-Wl5cgg&feature=related