In 1927 and 1928, the Staatsspoorwegen on Java received a total of 30 Mallets with the wheel arrangement 2-6-6-0. 14 had been delivered by the Dutch Werkspoor and the rest by the Swiss SLM. Initially they carried the numbers 1601 to 1630 and were renumbered to class CC50 in the Japanese era.
Although only cape gauge, they managed to haul 250 tonnes on exceptionally steep gradients of 6.5 percent with a speed of 45 km/h or 28 mph. They were replaced by diesel locomotives by 1984. Three were preserved and are on static display. CC5022 had been donated to the Utrecht museum in the Netherlands as early as in 1981. 