page_title: Rigid-framed electric locomotive
section_title: (1A)Bo(A1) and the 'Java bogie'
hierarchical_section_title: Rigid-framed electric locomotive / 1′Do1′ / (1A)Bo(A1) and the 'Java bogie'
caption_attribution_description: Nederlands: Nederlands Spoorwegmuseum loc NS 1010. Foto: Erik Swierstra.
context_page_description: 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.
  Some of these locomotives had their driving wheels coupled with coupling rods, as for steam locomotives. Others had individual motors for each axle, as would later become universal.
  By the middle of the century, the bogie arrangement for locomotives became more popular and rigid-framed locomotives are now rare, except for small shunters.
context_section_description: This little-known variant of the 1′Do1′ articulates the trucks at each end by forming a bogie with one driven axle and one carrying axle.
  Only a few examples of the (1A)Bo(A1) were built. They originated in Switzerland with the work of Jakob Buchli of BBC, later Swiss Locomotive and Machine Works. The first were four ESS 3000 express passenger locomotives, built by SLM and BBC in 1924 in Switzerland for the Electrische Staats Spoorwegen of Java. These gave their name to the 'Java bogie' for this form of articulation.
  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.
  They were followed in 1926 by the two JGR class 7000, later classified as ED54, for Japan, also built by SLM / BBC and with Buchli drives. These performed well, compared to other Japanese locomotives with nose-suspended traction motors, but were thought complicated and non-standard. With the culture of 1930s Japan and the increasing demand for self-reliance, rather than importing locomotives from overseas, they were used little and were withdrawn in 1948, despite this being the height of Japanese rebuilding post-war.
  A group of three different trial express passenger locomotives were supplied for the 1,500 V DC Great Indian Peninsula Railway in 1928. The first of these was most successful and followed by the EA/1 class of 21 and later the single EA/2. They were asymmetric, with a 2′Bo(A1) arrangement and a Java bogie at one end; a four-wheeled bogie at the other supported the electrical equipment. This electrical equipment was supplied by Metrovick but the locomotives were built by SLM and used their Winterthur drive, with paired traction motors above each axle, driving through a single central gear. The high-mounted motors were also found useful for services on flooded lines during the Indian monsoon.
  A derivative design was used for the Swiss 'double locomotives' of 1931, built for heavy freight service on the steep gradients of the Gotthard Railway. 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
  The Swiss SBB Ae 4/6 of 1941 was derived from half of the 'double locomotive', with a more modern flat-fronted cab at each end. 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. 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.
  In service, the Ae 4/6 performed well in some aspects, but had problems with a lack of adhesion and mechanical unreliability. Some aspects of their wartime construction may have red
caption: Dutch NS 1000
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