| Bavarian B IV | |
| Bgcolor: | 0081FF |
| Color: | FFFFFF |
| Builddate: | 1852–1853 |
| Totalproduction: | 10 |
| Leadingdiameter: | 915frac=8NaNfrac=8 |
| Driverdiameter: | 1524frac=8NaNfrac=8 |
| Over Bufferbeams: | 13639frac=4NaNfrac=4 |
| Axleload: | 10.3t |
| Serviceweight: | 28t |
| Weightondrivers: | 20.5t |
| Watercap: | 5m2 |
| Boilerpressure: | 7sigfig=3NaNsigfig=3 |
| Fireboxarea: | 1.3m2 |
| Evaporativearea: | 98.8m2101.2m2 |
| Cylindercount: | 2 |
| Cylindersize: | 406frac=16NaNfrac=16 |
| Pistonstroke: | 610frac=16NaNfrac=16 |
| Maxspeed: | 700NaN0 |
| Retiredate: | 1881 |
Bavarian B IVs were early German steam locomotives with the Royal Bavarian State Railways (Königlich Bayerische Staatsbahn).
The six engines built by Kessler were trialled with a Kessler boiler. This had a pear-shaped cross section and could therefore be set lower down between the wheels. The same effect was also attempted on the machines from Hartmann by using two boilers: a lower boiler with a small diameter and a larger, upper boiler. After two boiler explosions occurred, all the engines were equipped with normal boilers. All the vehicles had a steam dome in the centre, and the overhanging outer firebox had a flat top on which there was a safety valve and a pump (Fahrpumpe) driven by the crossheads.
They had Bavarian 3 T 5 tenders.