Mercedes-Benz-Blog TRIVIA: Mercedes-Benz Bus History - PART II


Stuttgart, Germany, Oct 30, 2008

The world champion bus in the guise of the O 321 H

* First Mercedes bus with new semi-integral design

* Basis of the brand face of Mercedes buses

* More than 18,000 units produced

Daimler-Benz really only got back into the swing of things with the O 321 H, a medium-sized forward-control bus with nine seat rows which impressed customers with a remarkably spacious luggage compartment beneath the floor of the passenger area. This was a result of the new self-supporting construction featuring a frame/floor assembly with a body firmly welded to it and serving also to support the structure. Kässbohrer in Ulm had come out with its first “Setra” in 1952, a circumstance which tremendously hastened the advent of the O 321 H (just three years after the O 6600 was introduced). Incidentally, Setra stands for selbsttragend (self-supporting).

Launched in 1954, the O 321 H set standards versus the competition particularly in styling. The avant-garde Mercedes designers limited the use of chrome, which the others used profusely, to a minimum. After all, the harmonious shape was supposed to develop an effect of its own. Dealers and customers took a very different view of this and loudly called for the usual tinsel. Not having to be asked twice, Daimler-Benz complied with these wishes, simultaneously demanding a hefty increase in list price. And suddenly it had a hot seller on its hands.

In 1954 Germany’s national soccer team won the World Cup for the first time. But few thought during production start-up that the new Mercedes-Benz bus would also prove to be made of world champion material. Taking into account chassis and production outside Germany, the versatile bus enjoyed worldwide unit production figures of nearly 30,000 over a long career spanning 16 years – more than any bus before it.
On December 6, 1954, St. Nicholas’ Day, the first O 321 H came off the production line in Mannheim, the plant that not long before had been declared the central bus plant of Daimler-Benz AG. Its semi-integral design was a major departure from the conventional chassis construction and, with the exception of the major drive assemblies, removed all similarities in design between buses and trucks once and for all. Just a few years earlier, the Mercedes-Benz O 6600 H had heralded this development, with its forward-control cab position and rear-mounted engine. Its body, however, had been built on an entirely conventional ladder-type chassis.

The backbone of the O 321 H on the other hand was a frame/floor assembly designed to be self-supporting. The body was then welded firmly to this high-strength frame. Together these two components resulted in an extremely rigid body shell, lending the overall design higher stability, lower weight and – with the removal of the chassis side members – a larger luggage compartment between the two axles. Coil springs on the front axle instead of the leaf springs used hitherto served to improve ride comfort. The O 321 H heralded a new era in Mercedes-Benz bus design.

At the same time, the separate frame/floor assembly of the new bus permitted the company to continue supplying conventional bodybuilders with the chassis. And coachbuilders in Germany and elsewhere gladly availed themselves of the opportunity to create individual body designs for buses of every conceivable kind.

Nevertheless, as a complete vehicle with three-pointed star, the original Mercedes-Benz O 321 H was pleasing enough to the eye in its own right. The curvaceous body created a thoroughly harmonious effect, the distinctive oval radiator grille incorporating the large brand symbol and circular headlamps. The same grille adorned the new cab-over-engine trucks of the 1950s – a feature clearly reminiscent of the legendary
300 SL – and forged an original brand bus face which still endures 50 years after the premiere of the O 321 H in the modern Mercedes-Benz Travego coach.

At the time of production start-up for the Mercedes-Benz O 321 H, buses were far less specialized than they are today. A single model series spanned the whole range from urban regular service bus to touring coach. But the O 321 H was more than up to the task. On the one hand, there was the regular service bus with wide, inward-folding doors ahead of the rear axle, destination indicator box and a soberly functional interior. And on the other, the vehicle came as a comfortable and elegant coach with airy, glass-bordered roof, entry behind the rear axle, hinged doors, luggage nets and finished in a variety of creative, multi-colored liveries.

Despite the wide range of equipment versions, the history of the O 321 H began with a single model, 9.23 meters in length and with a wheelbase of 4.18 meters – what today would be a midi-bus. Two years after its introduction, Daimler-Benz went a stage further with a longer version of the bus, the O 321 HL. Both wheelbase and overall length were extended by just under 1.5 meters. Until that point the coach could seat a maximum of 37 passengers; now at 10.6 meters in length and with two extra rows of seats the O 321 HL could accommodate up to 45 passengers.

In both cases the power was provided by a pre-chamber diesel engine mounted at the rear in the direction of travel. The six-cylinder in-line unit from the OM 321 series had a 5.1-liter displacement and delivered 110 hp. From 1962 the company responded to calls for greater output by offering the larger OM 322 5.7-liter in-line engine giving
126 hp. The power of both engines was transmitted by a fully-synchronized five-speed gearbox.

But it was not just length and technology that saw change: over the years the look of the Mercedes-Benz O 321 H was also revamped. While the early units were plain and unsophisticated in appearance, in time particularly the coaches went in for an ever-increasing abundance of chrome. This included not only the frame for the radiator grille, but also a broad molding below the front windshield, which continued along the sides and clearly marked the vehicle’s waistline.

Thanks to a number of facelifts, the O 321 H also gained in stature over the years. The original flat front windshield was enlarged and extended further downwards from 1957 on. In 1961 it grew again in size, this time upwards, providing passengers with a better view. Then, in 1963, the O 321 H was given a new rear end with a large, one-piece screen. Standing room also improved, thanks to a raised roof in the mid-section. But by this time the bus was approaching the end of an illustrious career in Europe. Already the first highly specialized buses were beginning to take over from the O 321 H: companion models, the O 317 and O 322, were now purely regular service buses.

Throughout its long history the O 321 H also enjoyed an international career. The bus plant in Mannheim turned out more than 18,000 of these bestsellers, roughly two thirds of which were complete buses, and one third chassis to receive bodies. Many of these buses were destined for export to other European countries, Africa and Asia. In 1965 the plant also delivered 116 parts kits to Greece and four to Argentina. Deliveries to Brazil were of a different order altogether, however: from 1957 to 1970 over 11,000 parts kits were shipped across the Atlantic. In total the then Daimler-Benz AG produced precisely 29,586 units of the Mercedes-Benz O 321 H / HL – a performance truly befitting a world champion.

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