Now, when I was surprised by the Polish inventor Tadeusz Tański from 1925, but in my new Feliks Roller gaze, this simple engine system was created ......
https://en.wikipedia.org/wiki/Tadeusz_Ta%C5%84ski
This is 12 cylinder dual boxer or H engine .. name Feliks-Tański engine..
Its movable parts are a double piston, a single piston pin, and Feliks Roller with lever...
Now there is NO lateral force of the piston and the croshead also ...
Andrew