The 4-10-4 of class 564C represented both the ultimate development and the dead end of the classical Doherty 6-cylinder layout. Although the prototype locomotive hauled 1700 tons gross up Rovniebera bank at 100 kmh, on the face of it an outstanding achievement, the cost of this performance was all too apparent. Consumption of coal and water was at least 25% higher than with the 564B. In addition, maintenance costs were higher and availability lower and it was these facts that really spelt doom for the 564C. A second locomotive, already on order, was completed before the trials were finished. The remainder were cancelled. The grate area was later reduced with firebricks, which improved the coal consumption somewhat, but the engines were living on borrowed time and were both withdrawn by 1982. The 564C was an expensive error that seriously endangered the continuation of steam development on the RSR.