Piko 58861 Umbauwagen Byg DB, Tp. IV

In the mid-1950s, the Deutsche Bundesbahn faced a major challenge: growing passenger traffic demanded modern passenger coaches, yet the existing fleet was outdated. The solution came with the conversion coach programme, in which proven underframes and bogies from older coaches were reused and fitted with new, robust steel bodies. The resulting four-axle conversion coaches (B4yg) featured fully welded underframes, central entrances with double doors without a centre pillar, and for the first time secure door seals. Thanks to their robust design, they reached a top speed of 120 km/h – a significant improvement over the three-axle predecessors. Between 1958 and 1959, 666 coaches of the B4yg-58 type were built, supplemented by variants with 1st/2nd class and luggage compartments. In total, more than 1,800 coaches were available for modern passenger services. Although withdrawal was already planned for the 1980s, many vehicles remained in service until 1990.