For the opening of the Samedan to Scuol railway line in 1913, the Rhaetian Railway needed a class of powerful electric locomotives. As the AC electric power supply technology installed along that line was still in its infancy, several manufacturers of electrical equipment were commissioned to build prototype electrical systems, to help develop an optimum locomotive. The mechanical components of all the locomotives fitted with these systems were fabricated by the Swiss Locomotive and Machine Works (SLM).
The first Ge 4/6 locomotive, no. 351, arrived in Graubünden in December 1912, with electrical equipment manufactured by Maschinenfabrik Oerlikon (MFO). It was thus the first electric locomotive acquired by the Rhaetian Railway. An identical sister locomotive, numbered 352, followed in February 1913. Later that year, a third Ge 4/6, numbered 391 and manufactured by SLM and AEG, joined the fleet. The last Ge 4/6 to be manufactured for the time being was no. 301, which was built by Brown, Boveri & Cie (BBC), and entered service in June 1913.
Several years later, in 1918, the Rhaetian Railway acquired another Ge 4/6, no. 302. That locomotive had been constructed by BBC in 1914 on its own account, as an exhibition piece. In the meantime, trial runs had shown that the MFO electrical equipment was the best suited to the needs of the Rhaetian Railway. A sub-series of a further three locomotives had therefore been ordered with slightly increased power ratings. They had been numbered 353 to 355, and had joined the fleet in 1914. (Textsource: Wikipedia)