As the Deutsche Reichsbahn suffered from a major shortage of wagons at the beginning of the 1920s, new passenger coaches of standardised design were procured from 1921 onwards.These were all to be designed with an iron body, but due to production problems most were delivered with a wooden body.  By 1930, more than 8250 of these wagons had entered service. The wagons were nicknamed  “thunder box” because the steel body tended to drone heavily. The name was then also applied to the wooden version of the wagons.
The Pwi 28 was used as a baggage car. In addition to a large loading space, it has a driver’s compartment with a pulpit and two dog compartments. These were used to accommodate dogs, as they were not allowed on the train in the past.