OPOC is one of the names given to the idea, Opposed Piston, Opposed Cylinder.I'm not opposed to tank engines, in fact I've been for a drive in one today
View attachment 17231
yes, that is me driving it.
Thing is, in the museum bit, they had this: -
View attachment 17232
Twin crank, one at the top and pistons meeting (well not quite) in the middle. Heard of them, but never actually seen one before
View attachment 17234