Well now here is a picture as I imagine my Feliks Roller. This is the version of Felix Commer4 of course a two-stroke version. in which the main torsion forces are transmitted through the maximum large areas of the "connecting rod", and are supported at the point where they work, and do not cause bending, as in the classic crankshaft. That is why it does not tend to fatigue the matariału. and relatively long trouble-free work .. And a little lower costs of doing....
Well, of course, the masses reciprocating a little smaller ..
Andrew