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 body-work panels.
Spectacular photos of a strength test
The new design had numerous advantages. The body was lighter than the previously used wooden skeleton with sheet steel paneling, and the new architecture also increased stability. At the time, spectacular photos dramatically proved the new body’s high load-bearing capacity, showing a large number of workers from the Sindelfingen bodywork plant assembled on the roof of the new bus, for example.
Unlike wood, steel does not splinter, accounting for the higher level of passive safety of the all-steel body – “… because injuries caused by wooden splinters are ruled out in the event of an accident, …” as a contemporary brochure put it.
Steel construction made in Sindelfingen
What’s more, special badges advertising “Steel bodywork from Daimler-Benz AG Sindelfingen” on the Mercedes-Benz buses praised the new engineering. While the bus chassis were produced at the Gaggenau plant at the time, the bodywork was the responsibility of the Sindelfingen plant; the latter had been Daimler-Benz’s “bus factory” since 1928. The large buses were the first to receive all-steel bodies, followed by the smaller models in subsequent years.
As early as 1935, Daimler-Benz was able to draw the conclusion that “all-steel bodies are used for the smallest as well as for the largest bus and all-weather vehicle because this design has proved superior to wooden bodywork structures in every respect.” The plant had thus converted the entire range of Mercedes-Benz buses to all-steel bodywork within the shortest conceivable time.