From looking at it I would not guess it to work like a mechanical head as we see them now.

I would think the back arms are used to just hold the cutting blades out. From the looks of it, it would appear to have a pretty decent sized cutting diamater. Maybe it was an attempt to make a large cutting head that was light and would plane less in the wind. Looks like you could fold the head down to put it into your quiver also.

Just a guess.