Umbauwagen

Six-wheeled Umbauwagen
Zwei dreiachsige Umbauwagen der DB
Number(s)	37001–38119 (AB) 85801–90537 (B) 99201–99926 (BPw)
Quantity	6582
Manufacturer	AW Hannover, AW Karlsruhe, AW Ludwigshafen, AW Saarbrücken, AW Limburg, AW München-Neuaubing
Year(s) of manufacture	1954–1960
Track gauge	1435 mm
Length over buffers	13,300 mm
Height	4,045 mm
Width	3,090 mm
Overall wheelbase	7,500 mm –7,900 mm
Top speed	85 km/h, later 90/100 km/h
Seats	AB: 16+245, B: 38+24, BPw: 24
Floor height	1,261 mm

The Umbau-Wagen or Umbauwagen was a type of German railway passenger coach operated by the Deutsche Bundesbahn (DB) which appeared in the mid-1950s. The name means "rebuild coach" and they were made by rebuilding or converting former state railway (Länderbahn) compartment coaches, many of which were over 30 years old.

After the Second World War, the DB, like the Deutsche Reichsbahn (DR) in East Germany, had a serious deficit of stock as well as a very aged fleet of coaches, a situation which lasted into the 1960s. In the 1950s the bulk of the fleet for local and Eilzug (semi-fast) trains was still made up of 22,345 four-, six- and eight-wheeled compartment and open coaches of the former Prussian and Bavarian classes from the period before and after the First World War. The few city coaches bought for Eilzug services at the beginning of the 1950s were nowhere near enough to replace and modernise the very outdated stock of passenger coaches and which was also costing considerably more to maintain. The levels of steel production and that of other raw materials of the newly formed Federal Republic did not permit a full replacement of the fleet in those days. Like the DR in the 1960s the DB was forced as early as 1953 to carry out a modernisation of pre-war coaches - plainly and simply called an Umbau or rebuild.

In summer 1953, the Bundesbahn Head Office tasked the Bundesbahn Central Office (Bundesbahn-Zentralamt or BZA) in Minden together with various coach building firms with designing a rebuild of the pre-war coaches, of which only the wheels and the undercarriage were to be used. The coach body was to be replaced by a completely new one.