Mercedes-Benz O 3500

(from DaimlerChrysler Press Release)  It almost sounds like a Christmas tale, but if the stories handed down through the generations are to be believed, the legendary Mercedes-Benz O 3500 did indeed celebrate its premiere on December 24, 1949. With this compact conventional bus, the then Daimler-Benz AG set itself a very special Christmas present: in next to no time, the O 3500 became the most successful bus in its day and age.
classic chassis design with a low frame

The first newly developed post-war bus with the three-pointed star was based on the L 3500 truck launched at the same time. And just like this truck, the bus had a somewhat lighter predecessor – the O 3250 (L 3250) – for a short period in the summer of 1949. Due to the family relationship with the truck, the Mercedes-Benz O 3500 had a diesel engine installed at the front, under a conventional hood. The design principle of load-carrying chassis with separately manufactured body fitted at a later stage was equally conventional. However, the chassis for the O 3500 featured a particularly low frame to give passengers a conveniently low entrance height.

Mannheim’s first step towards becoming a bus plant

Until then, bus bodywork had been built at the Sindelfingen plant of Daimler-Benz AG – the “made in Sindelfingen” label was regarded as a seal of quality. The Mercedes-Benz O 3500, by contrast, was manufactured in Mannheim, thereby launching Mannheim as the bus plant which continues to produce Mercedes-Benz buses to this day.

Just a few years after the end of World War II, the new O 3500 signified a turning point. Designed as a touring coach, it documented the end of the post-war period by responding to the desire to travel and to go on vacation. Many people spent their first holidays on board this coach, traveling across the Alps to Lago di Garda or to Switzerland. The touring coach version of the O 3500 featured generous glazing of the roof edges, allowing passengers to enjoy the view. A sliding roof over two-and-a-half meters long extended across almost a third of the vehicle’s overall length of 8.6 meters, letting in fresh air and sunlight. And lavish chrome trim combined with the popular two-tone finish – in red and black for instance – also underlined the beginning of a new era.

Smooth pre-chamber diesel engine with 90 hp

In the O 3500, the passengers in the 29 regular seats plus seven folding seats along the center aisle plus an occasional seat next to the driver had all the time in the world to enjoy the scenery outside as the coach traveled at the sort of leisurely top speed that was customary at the time: 82 km/h. The well-known OM 312 diesel engine worked under the long hood; with its further developed versions, it also acquired the status of legend in later years. The six-cylinder pre-chamber engine developed 90 hp from its 4.6 liter displacement. This is why the O 3500 is also known as the “Ninety” among connoisseurs. Typical features of this engine, which had its origins in a gasoline engine used in the licensed production of the Opel Blitz during and shortly after the war, were its high levels of flexibility and smooth running characteristics. The engine’s power was transmitted to the rear axle by a five-speed constant-mesh gearbox.

Luggage was stowed away in a rear-end compartment behind the rear seat bench, accessible behind two hinged doors. Additional small stowage compartments along the sides at floor level were optionally available. Since luggage space was rather on the short side, the Mercedes-Benz O 3500 coaches were frequently seen with roof-mounted luggage racks at the rear. Other optional equipment included head restraints on the double seats in the passenger compartment, particularly comfortable seats with center armrests and adjustable backrests, folding tables in the backrests and even single seats.

The O 3500 had been designed with easy handling and comfort in mind if you are to believe the contemporary brochures: “Alongside outstanding spaciousness and economy, the O 3500 excels in speed, easy maneuverability, dynamism and suspension quality – at levels previously only encountered in large passenger cars.” The advertising also expounded on the elaborate heating system and the ventilation with blower support in the O 3500: “As a result, you feel well and comfortable at all times, be it summer or winter.”

Family of touring coaches, country and urban buses

The compact O 3500 rapidly developed into a complete family of touring coaches, country buses and regular-service urban buses. From 1954, the line-up was complemented by a version with an additional seat row amounting to an extra 280 millimeters in length. While passengers boarded the touring coach through two hinged doors, the urban bus had a sliding door at the front and an inward-folding door at the rear, both already operated by means of compressed air. In the area of the rear seats of country bus and touring coach, the urban bus had a platform for 13 standing passengers.

The original Mercedes-Benz body on the chassis of the O 3500 was soon complemented by a large number of individualized bodies designed and manufactured by bodybuilders in and outside Germany. Another chassis popular among bodybuilders was the OP 3500 (P = Pullman) available from 1953, with the driver’s seat moved forward to a place alongside the engine and serving as the backbone for elegant cab-over-engine vehicles.

The most successful bus of its day and age with over 6,000 units produced

The versatility of the compact Mercedes-Benz O 3500 accounted for the vehicle’s great success in sales: between December 1949 and the discontinuation of production six years later, 6,049 units came off the assembly lines in Mannheim; of these, 2,644 were completely built-up buses. From the fall of 1953 until early 1961, precisely 1,675 chassis of models OP 3500 and its successor, the OP 311, were produced. The Christmas bus of 1949 thus became the most successful bus of its day and age.