At the time of the First World War, the government of the Canton of Bern decided that the branch lines of the BLS Group should be electrified and operated with the abundant water power available in order to do something about the acute shortage of coal. An electric locomotive had to be developed for these railways, which would achieve a low axle load and could replace the existing steam locomotives in all train types. This meant exactly that at 1.5 percent 310 tonnes should be pulled at 35 km/h, as well as 180 tonnes at 2.5 percent at the same speed. In addition, these speeds should not only be maintained, but it should also be possible to accelerate these weights from a standing start to the specified 35 km/h within four minutes.

To speed up development, a scaled-down version of the Be 4/6 introduced at the SBB at the same time was created. 14 units were initially built in 1920 and three more in 1924, which were slightly more powerful and 10 km/h faster. They were spread among the BLS subsidiaries and, if necessary, exchanged with one another. Since they were created by order of the government, they quickly earned the nickname “decree mills”.

In their original design, the locomotives had two bogies, each with two coupled axles and one carrying axle. The buffers and couplings, as well as small hoods were attached to the bogies. This meant that the locomotives could actually be assigned to the design of the crocodiles, which, however, was rarely actually stated due to the very small front end. The power came from a traction motor that stood on the bogies and drove a jackshaft.

Schematic drawing with dimensions

Locomotive Magazine, May 1921

Between 1954 and 1956, the carrying axles and front hoods were removed from the ten most recently built locomotives, since the branch lines could now cope with the higher axle loads. They could now come up with a higher adhesion mass and were given the designation Ce 4/4. The engines that were not converted were retired by 1973 at the latest, the converted ones between 1975 and 1988. Two units with only one traction motor were in service for a long time as shunting locomotives in the Böningen workshop. A Ce 4/6 and a Ce 4/4 are still preserved today.