Jerzi wrote:Em I wrong or right.
Did Carlsson have one 4wd car that didnt use belt or cains it has O-ring to deliver the power.
I talked to Rune Carlsson many years back and he tild me that he make the cockpits to the HIROBO helicopters.
Jerzi
You are correct, the Carlsson Viking 4WS 4WD did use O-rings.
Here is a picture showing the
4WD conversion kit you could buy to convert your 4WS to 4WD.

It worked but I can´t see that it worked well and it was changed when the Comet 4WD came
I know from an article in a old hobby magazine that he made parts for Miniature Aircraft USA to their helicopters.