Some fifty years of difference in tractive motion design: IORE 103 "Luleå" and 104 "Gällivare" at standstill with a loaded train waiting for Dm3 1215-1245-1216 "Josefina" with empties to pass.

One could argue if we're talking about just fifty years. The Swedish State railways (SJ) was a die-hard devoter of the coupling rod design and the 1960 Dm/Dm3 was basically just an incremental development of the original ore hauler class Oa from 1915 and the general-purpose class D introduced in 1925. The Co'Co' class M freight locomotives introduced in 1944 was one of the first boggie design on Swedish tracks and they were extensively tested out on Malmbanan. They were however inferior to the state-of-the-art class Of/Of2 used then and probably the coupling rod guys got additional ammunition to hold back additional boggie locomotive designs for many years to come. The Co'Co' class El15 was delivered to the Norwegian State railways (NSB) in 1967 and were put into operation on Malmbanan. SJ however remained sceptical and the class Dm was extended with the Dm3 section around 1970.

Based on the highly successful general-purpose Bo'Bo' class Rc thyristor locomotive introduced in 1967, a Malmbanan variant, the class Rm was introduced in 1977. With higher axle-loading and a different set of gears, the Bo'Bo' design was poorly suited for the heavy trains on Malmbanan and despite being put in multiples of three, they could not compete with the Dm3s. The class Rm were shortly after rebuilt and withdrawn from Malmbanan and life was back to normal. Around 1990, some major modernization and refurbishing were made to the 1200-series Dm3s and the 800/900-series were gradually taken out of service during the years to come.

As SJ was split-up and the rail traffic was deregulated, the ore traffic was taken over by a the MTAB/MTAS consortium owned by the mining company LKAB in 1993. As a part of the overall capacity increasing program, the 30-ton axle load Co'Co+Co'Co' class IORE was ordered. Delivered from Adtranz in Germany in year 2000, the class IORE will allow the train gross weight to be increased from today's 5200 tons to 6800 tons. One would think that the state-of-the-art IOREs would kill off the Dm3s, but the high demand for ore will require them to be in operation for some more years.

Note the ancient power line pylon to the right - a left-over from the 1913 electrification