German version

Mercedes-Benz O 4000 with diesel engine and steel body, 1930.

Wood had been the preferred material of coachbuilders. But then, from 1930, Daimler-Benz introduced the steel skeleton design step by step. For local public transport vehicles, a new all-steel body was introduced by Daimler-Benz as early as October 1930, making the buses sturdier and safer but nevertheless lighter.

This bus body was the precursor of present-day designs. On a chassis with a low frame, the coachbuilders mounted a filigree steel skeleton consisting of pressed U-shaped steel ribs and combining with cross and side members into a kind of cage. For stiffening the joints, the designers used so-called gusset plates. Rivets connected the elements with lasting effect and subsequently also served to fasten the bodywork panels.

The interior of the Mercedes-Benz O 4000, 1930.