A folding implement mountable on the three-point hitch of a tractor has a U-shaped, downwardly oriented, central member with a horizontal wing extending laterally from each side of the central member, behind the rear wheels of the tractor. Each horizontal wing has a series of downwardly extending tines...http://www.google.de/patents/US4228861?utm_source=gb-gplus-sharePatent US4228861 - Folding track removing implement
