Slowrotor thanks for the clear response.
If there is a continuous 1% slippage then the application could be suitable for reduction gears between engine and rotor head.
There must be other disadvantages, e.g. cold weather ops, that preclude the application in helicopters otherwise it would seem a way to avoid those Chip Light indications, noise (a sensitive factor) and apparently the manufacuring costs are less.
I have not seen this type of gearing employed by motor manufacturers and they are generally very quick to take up good technology ideas. We're in the motorcar business and our engineers are going to look int this concept to drive alternators and waterpumps and other functions if suitable.
However, getting back to helicopters, what or where would this be type of gearing/torque transfer be applicable?