The Germans, who in 1936 created the LBE (Lübeck-Büchener
Eisenbahn) train, went a little further in the construction of the
"double-deckers". In total, in the years 1936-1937, a total of
eight 6-axle two-section steel carriages of the DAB 6B type were
built, both of which were based on two-axle Jacobs Görlitz III1
bogies. This unprecedented solution, as well as pneumatic operated
doors, lighting, etc., as well as the construction of a special
locomotive with streamlined shapes, resulted in the fact that LBE
was quickly hailed as a "miracle of railway technology".
Five LBE sets were built in Wrocław at the then Linke - Hoffman -
Werke plants (later Pafawag Wrocław, now Bombardier Transportation
Polska), and three in Zgorzelec (Wumag Görlitz - later Bombardier
Transportation - Bahntechnologie - Germany GmbH & Co KG). Although
at that time these were not Polish cities, but German Breslau and
Görlitz. Another Polish thread, a bit gloomy, is the fact that
during World War II, at the Wumag Görlitz factory in September
1939, the Görlitz-Moys concentration camp, today Zgorzelec-Ujazd,
was created from a penal camp, through which over 120,000 .
prisoners and prisoners of war. Among them, several thousand Poles
who worked as slaves in the Wumag Görlitz factories, incl. in the
production of carriages or military equipment.
Sources: https://www.rynek-kolejowy.pl/wiadomosci/ciche-kolejowe-rocznice-60-lat-pietrowych-wagon-bipa-94914.html, https://www.drehscheibe-online.de/foren/read.php?031,374192,374193