333 locomotives of one basic design, delivered over an 18 year period from 1925 to 1943 is quite a remarkable achievement. The cost for each loco at the beginning was 214,000:- SEK, which was much cheaper than other European locos of the day. This was the 2-6-2 (or 1’C1’) electric locomotive, type ‘D.’ There have existed many variations of the D-loco, including a solitary 1’D1’ version, and in following the arrival of the Jeco H0-scale model of the Du-loco and the Roco H0-scale model of the Da/Dm/Dm3-locos at the FLMJ, we take a brief peak at the ‘D’ loco story!

It would not be unfair to distinguish between the ‘D’ and the ‘Da.’ The latter is very visibly different and was built much later, from 1952 to 1971 (arguably). The claim of 333 locomotives applies to the ‘D’ only. 321 of these locos were delivered directly to SJ, having been built by ASJ Falun, Motala Verkstad, and NOHAB Trollhättan. 9 of the others were delivered to BJ (Bergslagernas Järnvägar), and the remaining 3 to DJ (Dalslands Järnväg). These 12 were acquired by SJ in 1948 and are visibly different with slightly raked cab-end windows. Other detail differences have existed, most notably the fact that the first 134 locos had wooden bodies. Many of these were replaced with steel, and a few with “running repairs” had steel cabs flanking wooden engine-room bodies!

Although known as the ‘D’ series, and complete with number plates denoting this fact, the locos were in fact designated originally as ‘Dg’ or ‘Ds.’ The ‘Dg’ signified a loco geared for a top speed of 70km/h for Goods traffic, and the ‘Ds’ signified a loco geared for 90km/h for passenger (Snälltåg) traffic. This latter type increased the average speed on a Stockholm to Göteborg journey from 53km/h to 76km/h.

Later, the ‘Dk’ loco arrived, this having a different motor and permitted at speeds up to 100km/h. Loco 406 was the first ‘Dk.’ but a number of earlier ‘Dg’ and ‘Ds’ locos (the latter especially) were modified.

Loco 415 appeared as new, as a ‘Dr’ permitted to 120km/h, but was modified several times. For a brief period, loco 208 was modified to a ‘Dr’ but no other loco is believed to have received this modification. However, the nine locos acquired from BJ (where they were classified ‘Ds’) were out-shopped as ‘Dr2.’ Whilst classified ‘Dr’ or ‘Dr2,’ different profile coupling rods were fitted, but the designation was short lived. (The three locos acquired from DJ (where they were classified ‘Dk’) were out-shopped as ‘Dk2’).

Following service with loco types ‘F’ and ‘M,’ where more voltage steps were used in the controllers, a D locomotive was suitably modified (number 208, again, which was in works for repairs following collision damage), and this became ‘Df.’ In the early 1950s, it was used on trains 93 and 94, “The North Arrow” / “Nordpilen,” which were the heaviest express passenger trains in Sweden at that time (operating between Stockholm and Ånge / Långsele). It remained the solitary example.

The “1948 Locomotive Committee” decided to work on a prototype for a future ore train locomotive of the coupling rod type, building on a normal ‘D’ locomotive. The locomotive that was chosen for this experiment was number 136, which was already undergoing repair of collision damage and was being modified in some other respects. The locomotive was split at about the middle, and the framework was extended by two meters. An extra wheel-set, giving the locomotive axle notation 1’D1′, was also fitted. The locomotive, previously a ‘Dg,’ was fitted with a steel body and the type KJ-137 motors, while the previously used gearboxes for 75km/h were retained. The locomotive was delivered in the rebuilt state in 1950 and designated ‘Dg2.’ One year after the renovation the ‘Dg2’ was fitted with KJA-137 motors, as previously procured for the ‘Df’ loco. The motors for the ‘Dg2’ locomotive were re-designated KJB-137. These two motor types were prototypes for the generation of new motors for the ‘D’ locomotives, which ASEA had for some time been developing. The ‘Dg2’ locomotive was initially located in Bollnäs and served mainly the line, Ånge to Hallsberg. After some time the locomotive was transferred to Gävle, where it was used mostly as a strategic reserve for ‘Bk’ locomotives, but also for special transport tasks such as ore trains on the route Örbyhus to Domnarvet. Experience of the ‘Dg2’ locomotive as well as the previously mentioned ‘Df’ locomotive was widely used in developing the ‘Da’ locomotives.

The ‘Da’ was a result of the 1948 committee’s agenda, and although it shared the same chassis (more-or-less) with the ‘D,’ there were principle differences. The ‘Da’ had new bearings in the drive wheels, the cooling air intakes were placed on the roof, they had multiple links so that up to three locomotives could run together, and the look was more modern (slightly rounded body ends, better rubber-surrounded windows, etc). The ‘Da’ locomotive was instantly a universal locomotive, which could replace both ‘Dg’ and ‘Dk’ locos (the ‘Ds’ was now mostly ‘Dk’). On lines with up to 10‰ gradient the ‘Da’ locomotive can drive 650 ton of express train at 100km/h and 900-1000 ton of goods trains at 60-70km/h.

The newly developed traction engine type KJC-137 was manufactured not only for ‘Da’ and ‘Dm’ locomotives, but also for a large number of the ‘D’ locomotives, which by replacement of the engine and, where appropriate, fitting of gearboxes for 100km/h, became ‘Du’ and was thus transformed into a Universal loco. With ‘Du’ locomotives, it became possible to drive fast trains with 50 tons of trailer weight higher than with the ‘Dk’ at 90km/h and just as heavy goods trains with the ‘Dg’ at 60-70km/h.

In 1967, two ‘Du’ locomotives, Nos. 371 and 358, were prepared for multiple operating and relabelled ‘Du2,’ the first of many. As part of the modifications for multiple operating, the locomotives were provided with roller bearings on the coupling rods, and the lubrication facility was improved and supplemented with detection devices. Multiple coupled ‘Du2’ locomotives were allowed to take goods trains at a speed of 90km/h with a maximum train weight of 1300 ton, the same value as applied to ‘Rc’ and later ‘Ma’ locomotives. This would bring about a substantial improvement in standards for goods traffic.

The first withdrawal of a ‘D’ loco was in 1936, after number 106 caught fire! Larger scale withdrawals commenced 1962 at a modest pace, not really picking up until nearly ten years later. Today, there are no ‘D’ locos in service (a small handful have been preserved), but just a few ‘Da’ locos remain with the private operators. All ‘Dm’ and ‘Dm3’ locos have gone, but at least one ‘Dm3’ has been preserved. In 1986, Rc6 1396 broke the ‘D’ loco’s claim to the biggest type series, as it was the 334th such loco.

About the ‘Da’…

The ‘Da’ loco, as a single unit, remained just that, a ‘Da.’ On the Malmbanan Lulea-Narvik, it became necessary to replace the ageing ‘Of’ locomotives that pulled the ore trains. In connection with the ‘Da’ locomotive SJ ordered also a two-part version with shaft rotation 1’D+D1′ and known as ‘Dm’ (where the ‘m’ is said to signify ‘malm’). Many parts of the locomotives were built as ‘Da’ locomotives, but they had an extra driving axle (instead of one of the trailing axles) and only one cab. The first series of locomotives were in service during from 1953. In the 1960s, SJ ordered an additional fifteen locomotives, which were a little different in design. The loco had a new type of engine and a thicker frame, making them heavier and thus could benefit more. The earlier locomotives were rebuilt later on with the same engine type. Since the westernmost part of the Ore Railway (Ofotbanen) is in Norway, NSB has a Norwegian counterpart, the ‘El12.’ Four ‘El12’ locomotives were built for NSB 1954-1957.

A ‘Dm’ locomotive could pull trains weighing up to 3400 tons. To increase the capacity further, between 1960-1970 nineteen ‘parts’ of ‘Dm’ locomotive were built to allow the train weight to be raised to 5200 tons. These parts of the ‘Dm’, were built as an ordinary locomotive, but without cabs and trailing axle. They were type ‘Dm3’ and then connected permanently with the nineteen ‘Dm’ locomotives. ‘Dm3’ is now the term used to describe the whole 3-part loco, but it was originally just the centre unit. From 1979 and well into the 1980s most of the locomotives were modernised, the drivers-side cab doors were repositioned and the lights were changed to smaller Marshal headlights. Some locomotives remained in the original design.

‘Dm’ and ‘Dm3’ locomotives were used in the same rosters on the Ore Line. With rationalisation, the number of trains in the 1980s dwindled and most of the ‘Dm’ (20 locomotives without middle) were moved south to Bergslagen. There, they pulled the freight trains on the lines including Gävle-Borlänge until the early 1990s when the locomotives were scrapped. The ‘Dm3’ locomotive fleet continued to serve the Malmbanan until superseded by the IORE. In their final years, the locomotives were owned by Ore Transport in Kiruna (MTAB) who took over the ore traffic from SJ, and the locomotives were painted blue, and named after various mines. During the 1990s, locomotives were modernised further with enhanced driving cabs and upgrading of the mechanical and electrical systems.

The D series in model form

Over the years many smaller “cottage-based” manufacturers have produced various D-style locomotives. Rather than go into full detail here, we shall review the larger manufacturers’ more readily available models (that may be available second hand from time to time) and recent ‘local’ versions, but not the ‘collector’ ones which seem to cost almost as much as a full size one!

• Fleischmann introduced their Da loco in 1957 and different versions of it appeared in 1961, 1968, and 1971; each time as number 799 (the number was embossed so not cheap to change). It had a small switch at one end (in the driver’s open window) to change over from rail pick-up to catenary!
• Jeco produced the D loco as a ready-to-run plastic-body model from 2010, in at least four numbers. Despite the first ones being a little too fast (with poor slow-speed control), this is a very nice model. More versions have appeared with better speed control.
• Märklin introduced their Da loco in 1957, but believing that it had a limited market, also produced a version in green! Several modifications were made over the years (to the correct brown version), the last being in 1989. In 1985, Märklin introduced their wooden-body D loco using real wood, and from 1988 NEM couplings were fitted. No Hamo versions were ever produced, so this loco exists as a three-rail model only. In more recent times, Märklin (and Trix – for 2-rail) has released the Dm and Dm3 locos.
• Roco produces the Da, Dm, and Dm3. It is understood that the Dm3 was proposed (possibly sponsored) by LKAB following the success of the modern IORE locomotive model. The Dm3 was available in the modern blue livery, and a modern version of the brown livery (with LKAB markings). There was however, a limited run of it in true Epoch-IV brown (as a model of the loco that ended up down the side of the mountain and thus scrapped on site (1221+1240+1222) – the model is in running condition), and in the first non-standard blue livery. Following the success of this model, the Da was produced, and interestingly, in at least two versions with different wheels, number layouts, body mods and so on; all very subtle and did well to promote sales. The model has also appeared in post-brown liveries. The Dm is of course the Dm3 combination without the middle section and the model is offered in original condition only, thus for Iron Ore traffic.

Much controversy has been made at the FLMJ about a UGJ model of the Dm, but this was only ever a body kit and not really part of this review. Brimalm and NMJ have produced top-specification brass models of the Du2 and Dm3 respectively, but these are priced for collectors, not for railway modellers!

[Information mostly from “Boken om D-lokens historia” and “Järnväg.net,” along with Google’s Translation facility, the latter corrected where necessary!]