Swiss Federal Railways Ae 4/7

When the SBB needed more powerful locomotives for flatter lines in the twenties, the good experiences which had been made with the Ae 3/6^I were taken as the basis for the Ae 4/7. This was similar to its predecessor in many respects and had the same Buchli drive, but had one more driving axle. The two-axle bogie on one end was still used to carry the transformer.

While the mechanical part of all 127 locomotives was built by SLM, the electrical part was built by either BBC, Oerlikon or SAAS. Between these three manufacturers, there were some differences in the electrical equipment. Most locomotives originally had a Java bogie between one driving axle and the single carrying axle, leading to the wheel arrangement 2-C-A1. Soon this was removed, resulting in 2-D-1.

In the beginning, they were used in express service, also on the Gotthard. With the introduction of the Ae 6/6 in the fifties, the Ae 4/7 were withdrawn from the Gotthard. On flatter lines they were still used in express service, but only until the sixties when the Re 4/4^II was introduced.

After this, some Ae 4/7 were equipped with multiple controls and used double-headed with heavy freight trains. Single locomotives were also used in commuter traffic and with light freight trains. Large numbers were only withdrawn the nineties. The last ones were only withdrawn in 1996, 69 years after their introduction, when enough Re 460 had been delivered. Nearly 20 are still existing, with two being kept in operational condition by SBB Historic.