NSB Di 3 - Construction

Construction

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 grounding error caused the locomotive to be grounded 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.