SJ Dm3

Dm
A Dm3 in MTAB colors at Abisko Östra
Power type	Electric
Builder	ASEA
Build date	1953-71
Total produced	97 20 Dm+Dm 19 Dm+Dm3+Dm
UIC classification	1'D+D1' (Dm) 1'D+D+D1' (Dm3)
Gauge	1,435 mm (4 ft 8 1⁄2 in)
Wheel diameter	1.53 m (5 ft 0 in)
Length	25.1 m (82 ft) (Dm) 35.25 m (115.6 ft)(Dm3)
Locomotive weight	190 t (190 long tons; 210 short tons) 273.2 t (268.9 long tons; 301.2 short tons)
Electric system	15 kV 16⅔ AC
Current collection method	Pantograph
Top speed	75 km/h (47 mph)
Power output	4,800 kW (6,400 hp) (Dm) 7,200 kW (9,700 hp) (Dm3)
Tractive effort	940 kN (210,000 lbf) (Dm3)

Dm and Dm3 is a series of locomotives used by Statens Järnvägar (SJ) and later Malmtafik i Kiruna (MTAS) for pulling iron ore trains on Malmbanan in Sweden and Ofotbanen in Norway. A total of 39 double-locomotives (Dm) were delivered between 1953 and 1971, built by ASEA. A further 19 center locomotives (Dm3) were later delivered. Norges Statsbaner of Norway also operated 12 similar locomotives, designated NSB El 12. The Dm is a slower, freight-optimized version of the Da-locomotive.

History

The iron ore trains on Malmbanan between Luleå in Sweden and Narvik in Norway had been using the Of for a long time, and Statens Järnvägar chose to order new locomotives for Malmbanan at the same time as they ordered the Da-locomotives. At first 24 double locomotives were delivered in 1953, but in the 1960s SJ ordered additional 15 double sets. These were given more powerful engines, though the older five double sets were later rebuilt. These double locomotives could pull 3,400 tonne trains, but this was not sufficient during the end of the 1960s so SJ ordered 19 new center locomotives. These were mounted permanently between each of the Dm-locomotives, without its own drivers cabin, and designated Dm3. This allowed trains up to 5,400 tonnes. Instead of ordering Dm3s, NSB chose a different and more powerful locomotive, the NSB El 15. From 1979 and a few years onward the cabins were modernised, with new instrumentation and less noise.

In the 1980s most of the double locomotive sets were moved other places on SJs network. In 1996 the operation of Malmbanan was transferred to MTAB, who also took over all the triple engines and some of the double engines. They were redesignated Dm2 (for double locomotives) and Dm3 for triple locomotives. From 2000 the new IORE locomotives were delivered, and all the Dm2s and some of the Dm3s were taken out of service. In 2004 one set was donated to the heritage society Malmbanans Vänner, who also owns one El 12. MTAB has announced that they will take the Dm3 out of service by 2011 when enough IORE locomotives are available to relieve them.

External links

• Järnväg.net page on Dm/Dm3