The class D53, originally designated TF939, was a 2-8-0 freight locomotive introduced in 1912. It was a development of the D50, initially known as T524. It had the same driver diameter of four feet and three inches (1,295 mm) and the diameter of the cylinders had been increased from 21 to 22 inches. While the predecessor did not have flanges on the wheels of the second and third driving axles, the D53 had flanges on all axles. But now, the second and third driving axles had lateral play and the coupling rods had knuckle joints for additional flexibility. The dimensions of the boilers were similar.