The MO was a series of four- or five-axle diesel railcars built between 1935 and 1958 for the DSB. They were the more powerful successor of the MP and originally only had two two-axle bogies. The two diesel engines and generators were mounted on one bogie, while the traction motors where in the other bogie. There were five main variants called I to V, which each reached production totals of 2, 10, 10, 27 an 90. The first two variants were built by Burmeister & Wain and the others by Frichs. From variant III, the bogie carrying the engines and generators had again three axles like in the MP. The service of the last ones ended in 1984. 