It turns out that in Bell 206 the same circuit as in Bell 205 / UH-1, only there is no gyroscopic rod with a damper. Also one common horizontal hinge and tilting rotor. For some reason, it always seemed to me that on the B206 the usual common Yuryev-Sikorsky bushing, where the thrust turns the blades.
All the weight and stress of the entire aircraft is counting on the top of the mast and the little bit of metal attached to the main shaft. I would like to know what the mast is made of. That has to be on tough piece of metal. Especially with the extra long mast of the Robinson design.