Setting stroke on Douglas Shaper

[Shawn]

I borrowed this photo from Mayhem's post about his Douglas Shaper but the guts of mine look identical.



After looking at the photo I'm starting to wonder if loosening the ram and pushing it as far back as it would go while the yoke was horizontal like it is in the photo, maybe that indicator bar would make sense? seems like a rather involved way of setting the stroke lenght though.

Thanks
Shawn