Zeeoo,
I went to
www.rotex.com Good explanation about traction drive.
Still wondering if it has been used for a helo rotor transmission.
EESDL,
Interesting. I remember reading about the research at NASA way back in the 80's I guess. What became of it is the question.
Maybe its under wraps.
AC,
I think it would work in the same way a 45 degree bevel gears works. Just simpler.
Flight safety,
Are you sure about the "gap" between the rollers? And traction fluid that becomes solid in the gap? Very weird if true.
Thanks for your interest
slowrotor