The NS series 6100 consisted of ten 4-6-4T passenger tank locomotives. It was designed after the permissible axle load had been increased from 16 to 18 tonnes. Previously, the series 6000 with the same wheel arrangement was the most powerful tank locomotive in the Netherlands. The 6100 was based on the series 3700 “Jumbo” and like this had four cylinders. The firebox was kept nearly unchanged, but the surface area of the flues and tubes was reduced to carry the weight of the water supplies. The diameter of the cylinders had been increased by 20 mm to improve acceleration with trains of more than ten bogie coaches.

Numbers 6101 to 6105 were built by Hohenzollern in February and March 1929. 6106 to 6110 followed from Werkspoor in September to November of the same year, for a total of ten. No more were ordered in the thirties since the Dutch network was already being electrified. They were also called “Tenderjumbos”. After World War II, two had to be scrapped which were damaged and a third one got lost in the war. The seven others were withdrawn between 1956 and 1958.