They were conceived primarily for heavy express train duties on the winding and hilly Dresden to Hof trunk route through the Mittelgebirge.

Its design was related to the simultaneously developed 4-6-2 express locomotive Saxon XVIII H, but unlike the latter, it had a fourth coupled axle and a four-cylinder compound engine.

The engines fully met the requirements of a Mittelgebirge mountain locomotive, however its main disadvantage was its high coal consumption on the level.

The boiler was the largest of a German steam engine at the time the XX HV was brought into service and had exceptionally long heating tubes of 5.8 m in length.

The boiler was used in the Saxon XVIII H as well, with only minor adjustments to decrease its weight which resulted in a heating area that was smaller by 10 m2.

A special feature was the Lindner starting cock, already well known on two-cylinder compounds, which could supply additional live steam to the low pressure cylinders when working at over 60%.

The engine was originally heavily influenced by the dimensions of the turntables available in 1918 and was therefore not optimised for normal running.

New driver's cabs, Witte smoke deflectors, circular smokebox doors, a common cover for the steam dome and sand box as well as the arrangement of all pumps on a special mounting gave the engines a very different appearance.