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1948: The Mercedes-Benz O 4500 marks a new edition of bus design by Daimler-Benz
- Further development of all-steel design
- Lightweight design for great economic efficiency
- Generous space
It was a question of making the best of scarce resources in factories which had been destroyed during the war. But as early as March 1948, Daimler-Benz succeeded in “ re-editing” the Mercedes-Benz O 4500 bus. This vehicle featured the traditional “nose” but integrated it in an aesthetically highly appealing overall design. Its elegant appearance did not betray its pre-war origins – the bus had, in fact, been launched as early as 1941 but due to the war it was not until 1943 that large-scale production was started. Between 1943 and 1944/45, 300 units came off the assembly lines of the Gaggenau plant, all of them destined for the German armed forces.
Balanced design with an elegant touch
These conventional buses boasted a particularly elegant design – as if they knew that their days were numbered and that the cab-over-engine configuration was not to be stopped. More like a coquettish snub nose than an impressive hood, the conventional front-end blended into the overall design that expressed one quality more than anything else: sweeping elegance. This impression was created by styling elements like the vaulted roof, the rounded rear-end and a side contour that swept elegantly and airily, like a treble clef, from the hood and along the windows to bow graciously towards the rear-end.
Form creates function
Nobody would have been able to afford design as an end in itself in those hard years after the war, when few people owned cars and mobility was the realm of buses and railways. The novel, lightweight design of the O 4500 was attributable, at least in part, to an economizing approach, important raw materials still being to rationed. As early as 1949, Managing Director Wilhelm Haspel was able to say that “the problem of iron availability” would soon be a thing of the past, but the designers of the O 4500 – and of the O 5000 which joined it soon afterwards – had every good reason in the world to use the steel sparingly and to go for systematic lightweight design. The side walls, for instance, were maximally 50 millimeters thick. In spite of this, the O 4500 and the O 5000 boasted “an extraordinarily high level of vibration resistance” as a contemporary brochure emphasized.
The brochure text continues: “Great care has been taken to arrange and design all load-bearing elements so as to create clearly defined load structures and prevent torsional stresses to the greatest possible extent.” The vaulted roof served two purposes: it created extremely generous headroom in the area of the center aisle where interior height was 2,050 millimeters, and it gave the bus added stability that could not have been achieved with a cubic shape.
Generously dimensioned interior
Despite the bus’s relatively slim exterior width of 2,460 millimeters, enabling it “to negotiate narrow streets” as well, the designers succeeded in creating a generously dimensioned interior compartment. With an interior width of 2,250 millimeters, five comfortable seats were easily accommodated in the rear. The center aisle, too, did not have to fear comparison: it was “extra wide” according to the company and “unmatched when using the conventional two-seater rows.” So it was not just airy, sweeping elegance but also a certain measure of generosity that were en vogue in post-war years.
Demands on comfort were also becoming more exacting. Customers appreciated the care Daimler-Benz had taken in designing the heating and ventilation systems for the O 4500 and O 5000. A recirculating-air setting for the standard fresh-air heating was just one of many small details that distinguished the O 4500 and its larger brother, the O 5000. There was also a special duct blowing warm air across the windshield, thereby preventing the latter from misting or icing up.
In the late forties, air conditioning for the summer season was still out of the question, but this post-war bus series made up for this with a cleverly devised ventilation system. A contemporary brochure described this system as “ logically arranged flaps and ducts feeding fresh air into the interior without causing a draught,” recirculating the air in the passenger compartment on a permanent basis. Two large ventilation scoops on the roof provided for “draught-free ventilation of the underside of the roof.” The system was complemented by somewhat less sophisticated features which more likely than not did not deserve the “draught-free” seal: a crank-operated window on the driver’s side and three sliding windows plus one hinged window in the rear. The touring coach versions of both models were designed for 39 – 47 passengers. The city bus version had a capacity for 60 passengers.
Where the chassis of the O 4500 and O 5000 where concerned, Daimler-Benz opted for tried-and-tested assemblies. The Gaggenau plant supplied chassis with upper cowl panels, which, in the tradition of pre-war buses, were closely related to the low-frame truck chassis. Like the L 4500 and L 5000 truck models, the first post-war buses were powered by the proven OM 67/4 pre-chamber diesel engine.
This engine dated back to the thirties; its six-cylinder version was welcomed as a complement to the legendary 3.8 liter OM 59 – the first production diesel engine in a light-duty truck and the one that made the diesel engine in commercial vehicles popular in the first place. The technical data quote “120 hp peak output and 112 hp continuous output”, giving the O 4500 a top speed of 62 km/h and the O 5000 a top speed of 65 km/h or, with a special ratio, of as much as 75 km/h.
Link between conventional and modern bus design
The first small family of post-war buses did not remain in production for long, however. A total of 649 complete buses left the Sindelfingen plant between the spring of 1948 and the fall of 1950; total production including the chassis versions of the O 4500 and O 5000 came to 770 units. These models may have been a species doomed to extinction with their conventional design and low frame, and they had to leave the field to cab-over-engine vehicles and self-supporting bodywork before long, but they take the credit for symbolizing a new beginning in difficult times and providing mobility – much in demand at the time – in a straightforward and yet elegant way.