Thanks for posting.  I really enjoy the old machines of all types but this one has a real story to go with the history.

  In late 60's, the Ag Engr Dept of Univ of WI produced a 4 row, self propelled wheel track planter.  (Anyone recall the wheel track planting?  We used it for years.)  Anyway, so far as I know, Prof Bruhn was chair at the time--good guy.  Since 4 row was about all you could do with that type of design, chisel plowing rapidly took over and larger units became king.  I think the prototype just used 4 weighted truck tires to squash the track and there were just two wheels in back.  Not sure if steering was through the rear wheels or differential steering of the fronts.

  Thanks again.  Stetts