Hoy developed a heavy tank locomotive for heavy passenger trains on routes with many stops and gradients of more than two percent. With three coupled axles and a wheel diameter of 5 feet 8 inches, good acceleration and high speed should be achieved at the same time. They had a scoop device to fill up the water tanks while driving. The wheel flanges on the second coupled axle had to be removed later due to wear and tear on the rails. Since this brought new problems, they were put into shunting service as early as 1913. Because they were not suitable for this either, they were retired between 1920 and 1926.