In the 1920s stronger locomotives were needed for the Swiss plateau (which has grades up to 12‰). The existing locomotives with three driven axles were weak for their services. Because the Buchli drive already proved to be reliable on the Ae 3/6I, two prototypes of the Ae 4/7 were ordered in 1925. Subsequently, in total 127 were built between 1927 and 1935.[1]: 112–113
While the mechanical part was built by the Swiss Locomotive and Machine Works, the electrical equipment was built in three varieties, because these parts were built by three different manufacturers, Brown, Boveri & Cie. (BBC) (10901–10916, 10932–10938, 10952–10972, 11003–11008 and 11018–11027), Maschinenfabrik Oerlikon (MFO) (10917–10918 and 10973–11002) as well as Société Anonyme des Ateliers de Sécheron (SAAS) (10939–10951 and 11109–11017). The locomotives 10919–10931 were built by MFO but with BBC equipment.: 275–276 .

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