In the 1960s, the testing facility in Halle required another high-speed steam locomotive to test new passenger coaches. The new machine, 18 201, was developed from the high-speed tender locomotive 61 002 and parts of the high-pressure experimental locomotive H 25 024. A modified new boiler from the series 22, featuring an extended smokebox and a Giesl ejector, served as the steam generator. To ensure precise speed maintenance during high-speed runs, the locomotive was equipped with a counter-pressure brake. High-speed travel meant up to 175 km/h, as the 18 201 was initially approved for this maximum speed – later increased to 180 km/h – but only when moving forward.