How does a mini drill flexible shank work?

[abdulbadii]

TL;DR Summary

Help solve confusion on how the real mini drill flexible shank working mechanism

How is actually is a mini drill flexible shank working mechanism being able to deliver torque/energy/force so pliable ?

 

[Baluncore]

There is an inner core made from flexible multi-strand wire cable.
Outside that is wound a helix of steel wire, and then a counter-wound helix of steel wire.
Depending on the direction of rotation, the torque is transmitted by tension in one of the helical layers.

 

[Lnewqban]

Please, see:
https://patents.google.com/?q=Flexible+shaft&oq=Flexible+shaft

 

[berkeman]

Please, see:
https://patents.google.com/?q=Flexible+shaft&oq=Flexible+shaft

Which one of those patents apply to a drill extender? Most seem to be for surgical instruments...

 

[Lnewqban]

Which one of those patents apply to a drill extender? Most seem to be for surgical instruments...

I believed I had posted a link for a moto-tool flexible shaft instead.
Sorry, I can't find it again.