Mercedes-Benz eventually concentrated its entire bus production at Mannheim in March 1951. Construction of the O 5000 was discontinued in Sindelfingen, and production of the O 6600 was switched to Mannheim. But Mannheim also continued to build medium-duty trucks, including the L 4500, which made its debut in 1953 at the International Motor Show (IAA) in Frankfurt. This 4.5-tonner was a useful addition to the Mannheimers’ truck range alongside the popular 3.5-ton L 3500.

Big boys: Assembly of LA 3500 trucks in Building 12 of the Mannheim plant in October 1954.

New approaches to bus design
Mannheim was responsible for the first bus to be built according to an entirely new design in 1954, the O 321 H. This vehicle featured a frame floor assembly welded to the body to form a self-supporting entity - in common with passenger car design. Tribute was paid to this approach by the designers in Hans Pohl’s biography of Mercedes-Benz buses, where he referred to it as “an emancipation from the truck”. In contrast to the old method of combining chassis and bus body, this so-called semi-integral design approach, involving a highly rigid frame floor unit and welded body, offered greater stability and increased space.

By 1955, Mannheim was already Europe’s largest bus plant. During this period around 8,500 employees were engaged in the production of buses, trucks and engines. The focus of vehicle design was therefore shifting ever further towards the bus. Mercedes-Benz finally decided to abandon truck production at Mannheim in 1965 and to move it completely to Wörth. Back in 1960, Daimler-Benz AG had purchased industrial premises covering an area of 1.5 million square meters at Wörth near Karlsruhe, with a view to building the new truck assembly plant there. Construction work got under way in 1962, and the first truck - an LP 608 - came off the production line in July 1965.

Home of the bus: Photograph of a press reception to mark the launch of the Mercedes-Benz O 321 H model in Mannheim on December 6, 1954.