| SBB-CFF-FFS Bm 4/4 | |
| Powertype: | Diesel |
| Builder: | SLM, SAAS |
| Builddate: | 1960–1970 |
| Totalproduction: | 46 |
| Aarwheels: | B-B |
| Uicclass: | Bo′Bo′ |
| Length: | 12650- |
| Locoweight: | 72t |
| Tractionmotors: | Four |
| Transmission: | Diesel electric |
| Maxspeed: | 75km/h |
| Poweroutput: | 6200NaN0 |
| Operator: | SBB-CFF-FFS |
| Fleetnumbers: | 18401–18446 |
| Withdrawndate: | From 2006 |
The Bm 4/4 is a class of heavy diesel shunting locomotives built for Swiss Federal Railways. 46 examples were built between 1960 and 1970, numbered 18401 to 18446, and a limited number remain in service. Starting in 2006, the class was slowly being replaced by new Vossloh-built locomotives.