Because it was planned to run the train in shuttle services to a tight time schedule, it was necessary that the engine could run at top speed in both directions. This resulted in a tank locomotive rather than the tender locomotive design otherwise used for long-distance high-speed links. In order to be able to attain the high running performance aimed at, locomotive and coaches were designed to be especially light, albeit the coal and water supplies had still to be sufficient for a one-way trip on the planned route.
In building them, component designs from the Deutsche Reichsbahn’s standard steam locomotives (Einheitsdampflokomotiven) were used as far as possible but, in quite a number of areas, other components were used. The boiler overpressure was set at the higher level of 20 atm (293.9 psi), whereas those of the standard locos were operated at 16 atm (235.1 psi). Both locomotives were fitted with a streamlined shell. The water tank tapered at the front and gave the engine driver and stoker a good all-round view of the line. The “cover plates” covered the drive completely.
In contrast to the first engine, 61 002, which was built later, had a drive with three cylinders and larger supply tanks. To support the latter, the rear carrying bogie was extended to three axles. As a result of the more powerful drive, the punctuality of the train was improved – it had been unsatisfactory with 61 001. In addition the second locomotive had smoke deflectors on top next to the smoke exhaust, which were not fitted to 61 001.