Норвежские дизель-электровозы Di 3: История и эксплуатация

Class of diesel electric locomotives

NSB Di 3 is a class of 35 diesel electric locomotives built by NOHAB for the Norwegian State Railways (NSB). The class was built between 1954 and 1969, and delivered in two series, Di 3a and Di 3b. They are based on the Electro Motive Division F7 and are equipped with EMD 567 engines. They have a distinct bulldog nose and were numbered 602–633 (a series) and 641–643 (b series). The locomotives had a prime mover that gives a power output of The a series has a Co′Co′ wheel arrangement, while the b series has (A1A)(A1A). The b series has higher top speed, but lower tractive effort. The class was the dominant locomotive on NSB's unelectrified lines. It was ordered as part of the company's dieselization of services during the 1950s and 1960s, and was initially used on the three mainline routes of the Bergen, Dovre and Nordland Lines. In the 1960s the Bergen and Dovre Lines were electrified and the Di 3 units transferred to smaller lines, such as the Meråker, Valdres, Røros, Solør and Rauma Lines. They remained in service with NSB until 2001, five years later than planned due to NSB returning their successor, the Di 6. The units are still in use by the private operator Ofotbanen, the Kosovo Railways, an operator in Sicily, and the Norwegian Railway Museum. The class is similar to the DSB Class MY, NMBS Class 52–54, CFL Class 1600 and MÁV M61.

The first diesel locomotive used by NSB was a single Di 1 unit delivered in 1942. It was more cost efficient than the steam locomotives used on the non electrified lines, and in 1945, NSB decided that it would not order more steam locomotives. General Motors' Electro Motive Division (EMD) made a bid to deliver twelve units based on their F7, and NSB agreed to lease a single unit for trial. The body and mechanical components were built by NOHAB, the motors by ASEA and prime mover by EMD. While under production in 1954, GM shipped a G12 for trial in Norway and Sweden. It was tested on the express train on the Dovre Line on 7 August, but proved to have insufficient power, causing the train to be 20 minutes late. The trial unit from NOHAB was delivered on 17 September 1954. The first test runs in scheduled service were on the Nordland Line between Trondheim and Mo i Rana in October. There were no technical faults until 22 December, when a ground fault caused the locomotive to be out of service until 17 January. In March the unit was sent back to NOHAB and went on a marketing tour that would eventually reach Ankara, Turkey in 1955. The locomotive returned to Norway on 1 July 1955, where it was numbered 602 and put into service on the Nordland Line. The trials were successful, with much higher regularity than the steam locomotives. The Di 3 was used eight days in a row, and then spent a single day in the depot. NSB signed an agreement with NOHAB for delivery of five further locomotives. This caused a public debate, because the domestic supplier Thune had offered to build a similar locomotive in cooperation with American Locomotive Company. The first delivery was made on 25 April 1957, and the order completed by July. In March 1957 NSB received permission to buy another eight locomotives. Delivery started in October and was completed on 1 June 1958. The order was supplemented with another six trains, with delivery in 1958. The Finnish State Railways (VR) ordered five units in 1959, but these were cancelled for political reasons. The units were offered to NSB for a reduced price. Three were designated Di 3b because they had a slight specification variation, with a (A1A)'(A1A)' wheel arrangement and higher top speed. Two units had come short enough in the production process that they could be given the same specifications as the other Di 3a units, but received a slightly longer body. The Di 3b were given the numbers 641–643. For part of 1960, no. 623 was leased by NOHAB and sent on a demonstration tour in Eastern Europe. This resulted in an order from the Hungarian State Railways, where it became the MAV M61. The Røros Line was upgraded and the Bergen Line units transferred to Trondheim in 1960, but increased need for hauling forced NSB to not use the units on the Røros Line until the delivery of the next batch of six units in 1965. The final delivery, of four units, was made in 1969.

The initial use for the Di 3 was to operate the three non electrified long distance lines of NSB: the Bergen Line, the Dovre Line and the Nordland Line. Following the delivery of the first batch in 1957, they were from 2 June used on the Dovre Line, north of Otta to Trondheim, and further north along the Nordland Line to Mo i Rana. The stock was sufficient to replace all steam locomotives on the Nordland Line, and reduced travel time by one hour. From Hamar to Otta, the track did not have sufficient permitted axle load. From the second batch of eight units, five were put into service on the Bergen Line, the rest on the Dovre and Nordland Lines. Necessary upgrades of the permitted axle load had been made to the Dovre Line and Nordland Line, and the locomotives were in use from Hamar to Saltdal. On 30 November, the Nordland Line was completed to Fauske, and the full length operated with Di 3. The first section of the Bergen Line, the Gjøvik Line and the Roa–Hønefoss Line, was electrified in February 1961. This allowed diesel and electric locomotives to haul all trains from Oslo to Bergen. In 1962 the Nordland Line was completed to Bodø, but the increased need for locomotives was more than compensated by the electrification of the Bergen Line being extended to Ål. The first Di 3 ran on the Røros Line in 1964, that had previously been denied due to bridges with insufficient axle load permits.