An initial series of five prototypes was procured by a consortium made up of the Furka Oberalp Bahn (FO) and the SBB-CFF-FFS, which wanted them for the Brünigbahn, now known as the Zentralbahn (zb). Once the type had been proven, the members of the consortium ordered a total of 11 series production units, and the Brig-Visp-Zermatt-Bahn (BVZ) ordered another five such units.
The class is so named because it was the second class of locomotives of the Swiss locomotive and railcar classification type HGe 4/4 to be acquired by each of the three railway companies that procured it. According to that classification system, HGe 4/4 denotes a narrow gauge cogwheel-equipped electric locomotive with a total of four axles, all of which are drive axles.
*) The chassis of locomotives 1951 and 1952 were fitted with new bogies (Abt system) and transformers (11 kV) and delivered to the FO as nos. 104 and 105. The prototype bogies (Riggenbach system) and transformers (15 kV) salvaged from those chassis were then fitted to the last two series production locomotives delivered to the SBB-CFF-FFS Brünigbahn.
