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The Swiss locomotive class Ae 4/6 was a class of electric locomotives. They were intended as a powerful locomotive for the steep gradients of the Gotthard Railway, but smaller than the huge 'double locomotives' which had previously been tested there. They were built from 1941, during World War II, and although Switzerland remained neutral through this, material shortages led to some quality problems with these locomotives.
The SBB Ae 4/6 was needed for service on the steep gradients of the Gotthard Railway. Electric locomotives were needed, rather than steam, both because of Switzerland's dependence on imported coal, and also because of the ventilation problems in long tunnels. Existing electric types, such as the Ce 6/8I, Ce 6/8II 'crocodiles' and the Be 4/6 of the early 1920s had been powerful enough for the gradients, but their use of a coupling rod drive limited their speed. A new express passenger locomotive would require independent traction motors for each axle.
In the 1930s, three new prototype 'double locomotives' were produced, the Ae 8/14. These were faster, from the previous 75 kilometres per hour (47 mph) to 100 kilometres per hour (62 mph), and abandoned rod drives in favour of separate motors and Buchli drives, or later the Winterthur universal drive, to each axle. The last of these was the LandiLok, with a modern streamlined bodyshell. [3] These locomotives were powerful, but also inflexible, and only heavy goods trains, rather than the intended passenger expresses, could make use of their full power. [4]
The SBB Ae 4/6 design originates with four ESS 3000 express passenger locomotives, built by Swiss Locomotive and Machine Works (SLM) and Brown, Boveri & Cie. (BBC) in 1924 in Switzerland for the Electrische Staats Spoorwegen of Java. They were a development of the rigid-framed 1′Do1′ arrangement, but Jakob Buchli articulated this at each end, giving rise to their name of the 'Java bogie' for this (1A)Bo(A1) form.
Only a few examples of the (1A)Bo(A1) were ever built. The bogie was arranged so that the pivot axis was just behind the pivoted driven axle. The axles were driven by Buchli drives, to permit suspension movement, and as the pivot was so close to the axle this linkage could also absorb the bogie's movement, as the driven axle twisted in place but did not move sideways by much.
A derivative design of this layout was used for the Swiss Ae 8/14 'double locomotives' of 1931, built for heavy freight service on the steep gradients of the Gotthard Railway. [4] These consisted of two articulated units as (1A)A1A(A1)+(1A)A1A(A1). A further unpowered carrying axle was also provided, splitting the central Bo group into A1A, which was needed by the extra weight of the transformer for the Swiss low frequency AC system. Again this was only a small class of three locomotives classed as SBB Ae 8/14, although each of the three was different. The first used the same Buchli drives, but from the second they introduced the Winterthur universal drive, with paired traction motors driving each axle through a single central gear. This could be adapted more easily to the articulation. A drawback to the sheer size of these locomotives is that there were few trains heavy enough to require them, and when used to the full they were at risk of over-straining their couplings. [4]
The third of these was built as the 'LandiLok' and exhibited at the Swiss National Exhibition of 1939 .
The Ae 4/6 was derived from half of the 'double locomotive', [4] with a more modern flat-fronted cab at each end. [5] Weight saving in the traction motors allowed a return to the (1A)Bo(A1) layout, with the Java bogie and the Winterthur drive, and avoiding the central carrying axle.
They were also intended for use on the Gotthard route, but more flexibly as they could be used as individual units for lighter trains, or run in multiple as pairs for heavier trains. [4] Multiple working equipment was fitted from the outset, although not much used in service as both it, and the locos, were considered unreliable. [1] This was also the first class to be driven from the left of the cab, rather than the right.
Both these and the Ae 8/14 had used regenerative braking, useful for descending the Gotthard's steep gradients without overheating and also returning electrical power to the network. The Ae 4/6 had a simplified and lighter system, where one traction motor could serve as the exciter for the others during braking. They were also built with aluminium windings in the transformer and motors, rather than copper, owing to wartime shortages. Aluminium was also used for some parts of the frame and bodyshell. [2]
A problem with the Ae 8/14 was that it had a large number of transformer tappings, and could only change slowly between them. This limited their best acceleration, no matter how light the train, to a minimum of a minute to reach full speed. [6] The Ae 4/6 avoided this by using fewer tappings, with faster actuation between them. An air-blast main high voltage circuit breaker was also used.
The Winterthur drive is a geared drive on the centreline of the locomotive, giving room for a traction motor each side, two to an axle. The two motors were geared by spur gears to a central layshaft carrying a third gear which drove a drive wheel on the axle. This drive wheel was not fixed rigidly, but was connected to the axle by four pivoted links in a square arrangement. [7] The large number of gears used, and that these were straight-cut spur gears, led to high noise levels. When combined with some issues from wartime construction, the drive transmissions were not perfectly reliable.
In service, the Ae 4/6 performed well in some aspects for measured power, but had problems with a lack of adhesion and mechanical unreliability. Some aspects of their wartime construction may have reduced their mechanical build quality, leading to high noise levels in the final drives, and a susceptibility to overheated bearings and gear failures, particularly after wheelslip.
Construction was by Swiss Locomotive and Machine Works (SLM) for the mechanical construction and Brown, Boveri & Cie (BBC), Maschinenfabrik Oerlikon (MFO) and Société Anonyme des Ateliers de Sécheron (SAAS) for the electrical equipment. They were built in two batches, the first six being delivered in 1941–1942, the second six in 1944–1945.
The second batch, 10807–10812, were rebuilt between 1961 and 1966 to try and improve their reliability. The flexible drive wheels of the Winterthur Drives were replaced with Brown Boveri spring drives, [2] [7] as were used for the Ae 6/6 [8] This also reduced their top speed and increased their weight. [1]
| Number | Commissioning | Withdrawal |
|---|---|---|
| 10801 | 26 April 1941 | July 1965 |
| 10802 | 14 June 1941 | February 1977 |
| 10803 | 26 May 1941 | October 1980 |
| 10804 | 25 July 1941 | October 1980 |
| 10805 | 12 September 1942 | May 1983 |
| 10806 | 31 December 1942 | October 1982 |
| 10807 | 31 August 1944 | February 1977 |
| 10808 | 1 November 1944 | March 1981 |
| 10809 | 5 April 1945 | March 1981 |
| 10810 | 31 May 1945 | April 1982 |
| 10811 | 27 March 1945 | May 1983 |
| 10812 | 5 February 1945 | December 1982 |
The locomotives were in service from their arrival until the mid-1960s. After this they began to be replaced in first-line service by their successors, the SBB Ae 6/6. With a 375-tonne (369-long-ton; 413-short-ton) train, they could reach a speed of 75 km/h (47 mph) on a 26‰ gradient. [9]
The first out of service withdrawals begin in 1977. Selling the whole class to Südostbahn (SOB) was considered in 1980, but their lack of adhesive weight went against them, compared to a more modern bogie locomotive. The SOB operated heavy biannual pilgrimage trains to Einsiedeln Abbey, using Re 4/4III for the 5% gradients – nearly twice those of the Gotthard. The Ae 4/6 was considered for this as it was powerful enough, but their poor adhesion meant that more Re 4/4III were bought instead.
A Dutch class, the NS 1000, were ordered from the same makers but were delayed by the war until 1948. Three were built by SLM, but the remainder were licence-built by Werkspoor in the Netherlands. Although designed as passenger locomotives with a top speed of 160 kilometres per hour (99 mph), they were soon found to be unreliable when used at speed and spent their working lives restricted to 100 kilometres per hour (62 mph) and mostly freight services. Despite this, they stayed in service until 1982.
After 10801's fire in 1965, it was scrapped. [2]
General withdrawals began with 10802 and 10807 in 1977, then the whole class was withdrawn from 1980 and scrapped at Biasca, the last in 1983. [2]
None were preserved, although one side of a driving cab is preserved in the Museum of Transport at Lucerne.
Crocodile electric locomotives are so called because they have long "noses" at each end, reminiscent of the snout of a crocodile. These contain the motors and drive axles, and are connected by an articulated center section. The center section usually contains the crew compartments, pantographs and transformer.
The Ae 6/6 is a heavy electric locomotive used by the Swiss Federal Railways (SBB). It is sometimes also referred to as canton locomotive ("Kantonslokomotive"), because the first 25 locomotives were named after the cantons, and carried the canton's coat of arms on the side and chrome embellishments, and the Swiss coat of arms on the front, between the chrome stripes. These adornments made them internationally famous. The other 95 locomotives received the names of capital cities of Swiss cantons, and other towns and cities, but without the chrome embellishments. The namings were held as ceremonies in the respective cities. A less flattering moniker is Schienenwolf as the three axle bogie construction stresses the tracks heavily.
The Re 620, Re 6/6 in the old numbering scheme, are six-axle, electric locomotives of the SBB-CFF-FFS, which were acquired as a replacement for the Ae 6/6 for heavy services on the Gotthardbahn. They are the most modern of the so-called "Gotthard locomotives".
The Buchli drive is a transmission system used in electric locomotives. It was named after its inventor, Swiss engineer Jakob Buchli. The drive is a fully spring-loaded drive, in which each floating axle has an individual motor, that is placed in the spring mounted locomotive frame. The weight of the driving motors is completely disconnected from the driving wheels, which are exposed to movement of the rails.
The Ae 4/7 was a universal locomotive of the Swiss Federal Railways, employing the so-called Buchli drive.
Jakob Buchli was a Swiss design engineer in the field of locomotive construction.
The Ae 4/8 was a prototype locomotive of the Schweizerischen Bundesbahnen (SBB) for the testing of electrical operation. The locomotive was equipped with two different drives, therefore acquiring the nickname Bastard. Because of its three-part locomotive body it also acquired the nickname Tatzelwurm.
The Be 3/5 11201 was one of four test locomotives ordered by the Schweizerischen Bundesbahnen (SBB) in June 1917. Intended to provide experience with electric traction, the locomotive was intended, along with Be 4/6 12301, Be 4/6 12302 and Ce 6/8I14201, to be used on services on the Gotthardbahn. The Be 3/5 was something of a stopgap offered by Maschinenfabrik Oerlikon (MFO) because they felt that the requirements required for the Gotthard Railway could not be fulfilled at the time. As the MFO did not feel that it could produce a freight locomotive with six drive-axles, a smaller version of the BLS Be 5/7 was offered. This meant that the locomotive did not fulfil the SBB specifications for the Gotthard line; it was too weak and, compared with the A 3/5 steam locomotives, too slow. However, due to a lack of available stock, the railway still took delivery of the locomotive. After a long operational life it was scrapped in 1973.
The Be 4/6 12301 was one of four test locomotives ordered by the Schweizerische Bundesbahnen (SBB) in June 1917. For gaining experience for ordering electrical locomotives this locomotive should – as her three sisters Be 3/5 12201, Be 4/6 12302 and Ce 6/8I14201 – have been used for services on the Gotthardbahn. The Be 4/6 12301 was the alternative design of MFO for a fast train locomotive for the Gotthard railway line. She was designed and built according to the requirement specifications of the SBB. But – except for occasional trips to the maintenance shop of Bellinzona – did not appear on the Gotthard railway line. The design was intrinsically reliable. The locomotive operated for 44 years in very various services. The locomotive drivers liked the locomotive because her driving behaviour was very smooth even at top speed. But technically the locomotive was much more complicated than their sisters Be 4/6 12302 and Be 4/6 12303-12342.
The Be 4/6 12302 was one of four test locomotives ordered by the Schweizerische Bundesbahnen (SBB) in June 1917, along with the Be 3/5 12201, Be 4/6 12301 and Ce 6/8I14201. It was intended to be used on the Gotthardbahn, in order to gain experience in ordering and operating electric locomotives, However, the Be 4/6 12302 was never used for scheduled services on the Gotthard, because at its introduction it was already outperformed by the successor class Be 4/6 12303-12342.
The Ce 6/8 I 14201 was one of four test locomotives ordered by the Schweizerischen Bundesbahnen (SBB) in June 1917. For gaining experience for ordering electrical locomotives this locomotive should – as its three siblings Be 3/5 12201, Be 4/6 12301 and Be 4/6 12302 – have been used for services on the Gotthardbahn. The development of freight locomotives subsequently took a completely different way which was not conceivable at the ordering date. The Ce 6/8I came into service only after the first Ce 6/8II.
The SBB Ae 8/14 is a class of electric locomotives built for Swiss Federal Railways to be used on the Gotthard railway. Only three prototype engines were built between 1931 and 1938, each of them in a different design.
The Be 4/6 was a bogie locomotive operated by the Schweizerischen Bundesbahnen (SBB) on the Gotthard Railway along with the Be 3/5, The design was based on the prototype Be 4/6 12302.
A monomotor bogie is a form of traction bogie used for an electric locomotive or diesel-electric locomotive. It is distinguished by having a single traction motor on each bogie.
Midi E 3301 was a prototype electric locomotive of Class E 3300 designed for the Chemins de fer du Midi, France. Because of poor performance, it was refused by the Compagnie du Midi and was re-deployed to Swiss railways. On 1 May 1919, it was classified Fb 2/5 11001 and, in 1920, it became experimental locomotive Be 2/5 11001 of the Swiss Federal Railways (SBB).
The Tschanz drive or Oerlikon single-axle drive is a fully sprung single-axle drive for electric locomotives named after its inventor Otto Tschanz or after Maschinenfabrik Oerlikon. The drive was not widely used because its competitor, the Buchli drive, was cheaper and lighter.
Rigid-framed electric locomotives were some of the first generations of electric locomotive design. When these began the traction motors of these early locomotives, particularly with AC motors, were too large and heavy to be mounted directly to the axles and so were carried on the frame. One of the initial simplest wheel arrangements for a mainline electric locomotive, from around 1900, was the 1′C1′ arrangement, in UIC classification.
The Java bogie, was a bogie for electric locomotives manufactured by the Swiss Locomotive and Machine Works (SLM). It contained a driving wheel and a trailing wheel. It got its name because it was first installed in the 3000 series express train locomotives delivered to the Electrische Staats Spoorwegen (ESS) on Java in 1925.
The 2D2 9100 was a class of electric locomotives operated by the SNCF in France, introduced in 1950. They were a development of the pre-war 2D2 5500, built during the post-war push for increased electrification.
The Indian locomotive class WCP-2 is a class of 1.5 kV DC electric locomotives that was developed in late 1920s by Swiss Locomotive and Machine Works (SLM) for Indian Railways. The model name stands for broad gauge (W), Direct Current (C), Passenger traffic (P) engine, 2nd generation (2). They entered service in 1938. A single WCP-1 was built at England in 1938.
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