this is a 'rotative beam engine' http://en.wikipedia.org/wiki/Beam_engine I am going to stop pretending I understand how it works, but the flywheel and its axle go out beyond the engine house (see http://www.pbase.com/crisscross/image/144407789/original ) where 2 further cable drums used to bring ore up from below.
copyright; please look at ORIGINAL size