A folding frame for an agricultural implement such as a wheel rake. The frame includes ground engaging wheels and two toolbars foldable for operation and for transport. The folding frame is provided flexibility to conform to uneven surfaces, yet stability against the torques and forces of operation. A slidable tongue provides folding action between the transport position and the operating position. A spacing between rear ends of the two toolbars may be altered hydraulically for wider or narrower windrows. A novel caster wheel provides support for the toolbars and is located so that the implements transport position is narrower than the prior arts.