Swiss Federal Railways Bm 4/4

The Bm 4/4 was a four-axle diesel shunter designed as a replacement for the last steam shunters that does not need overhead lines. As this also had strategical reasons, the Swiss Military Department also paid for some of these locomotives. A total of 46 were completed between 1960 and 1970. While the first 26 had a length of 12,650 mm, the last 20 measured 13,150 mm.

All were powered by a V12 from SLM with twin turbochargers and intercoolers. This engine delivered 620 kW or 840 hp and transmitted its power via a SAAS generator to traction motors on all four axles. Meanwhile, they are not working anymore at the SBB. Ten were still existing in 2025, only two of them are still in service for Rhomberg-Sersa Rail Group. Some are stored, others are preserved in operational condition.