The last of the “one for all” buses: O 302

Oct 30, 2008
  • A generously glazed cuboid
  • Enormous range of variants
  • Exports as far as the USA
With specialization proliferating among trucks more than ever before in the 1960s, the new O 302 bus put on the market in 1965 gave it one more – extremely successful – try as a classic generalist. One for all – probably the aptest description of the Mercedes-Benz O 302. Urban regular-service bus, rural-service bus, touring coach – this bus with the three-pointed star was a jack of all trades. And it was the last of its kind before buses became specialized.
Launched in May 1965, the O 302 replaced the popular O 321 H, and the step from one to the other could hardly have been greater. The expectations made on the new O 302 were enormous considering that the O 321 H had scored worldwide success with over 18,000 units built in 13 years. While the predecessor’s rounded contours and small windows identified it as a design from the 1950s, giving the bus a slightly outdated appeal toward the end of its career, the O 302 had been designed in the austere automotive Bauhaus style of the 1960s. The curvatures of roof and back did little to deter from the basic cuboid shape with steeply angled front, generous glazing, slim window pillars, long side windows and large rear screen.
A typical child of the economic miracle period
Typical luxury features in the 1960s were the chrome surrounds of all windows. The
O 302 was a product of the economic miracle period in Germany: people had gained new confidence and wanted to see and be seen.
Only the broad scuff plates and trim strips of the O 302 were still reminiscent of the 1950s. A bare sheet-metal band ran across the front end and connected it with the sidewalls. On many O 302 units, a broad strip or color band extended along the sides, from the front to the rear bumper, giving the bus a well integrated appearance.
Otherwise the O 302 with its clear and cool lines carried on the design trend that the Mercedes-Benz O 317 had established in 1958 (though still with small side windows). But whereas the O 317 with its convex grille looked rather grim, the O 302 with its horizontal grille and large rectangular headlamps had a much more conciliatory mien.
Only a narrow strip now divided the windshield
The O 302 was available with plane side windows or with curved glazing. The latter extended into the roof, thereby converting the bus into a classic panoramic vehicle. On this version, the rear door was adapted to the side contour by means of an additional window at the top. The panoramic glazing had first and foremost been designed for touring coaches but was also optionally available for the regular-service buses with their destination indicators. In the beginning, roof edge glazing could be had to supplement the plane side windows. The driver’s workplace in the Mercedes-Benz
O 302 was visually separated from the passenger compartment in that the lower edges of windshield and front door windows formed a single line that was clearly below the passenger compartment’s window sills. In the versions with high, curved side windows, the roof was slightly raised in the area of the passenger compartment. The windshield now only was divided by a narrow vertical strip.
Diversity was one of the special hallmarks of the three-meter-high bus with its high floor: it was available with four wheelbase lengths between 9.6 and 11.9 meters (the longest version joined the series in 1967). Equipment and seating versions also varied greatly, ranging from practical urban buses through to upmarket touring coaches. Hinged doors front and rear were available for the touring coach, two-part outward-folding doors front and rear for the country bus, and extra-wide inward-folding doors at the front and in the middle for the regular-service urban bus – the O 302 made use of every opportunity that its body afforded.
Characteristic of the O 317 is a horizontal underfloor engine arranged between the axles, while the O 302 draws on the advantages of the rear-mounted engine, much like the O 321 H. The O 302 was also the first bus with the three-pointed star to be fitted with a direct-injection diesel engine, in 1965, two years after its introduction in trucks, Until then, Mercedes-Benz had preferred pre-chamber combustion engines which boasted smoother running characteristics but also consumed more fuel.
230 hp available on request
Initially, buyers had to put up with the compact OM 352 six-cylinder in-line unit with a displacement of 5.7 liters and an output of 126 hp as standard-equipment engine in combination with a five-speed gearbox. The large twelve-row bus was powered by the OM 327 with a displacement of eight liters and an output of 150 hp, soon to be boosted to 160 hp. The more powerful engine was optionally available for the smaller O 302 versions. The twelve-meter bus was optionally available with the large 11.6 liter OM 355 with 230 hp – a more than adequate engine output for touring coaches as well. From 1969, the power output of all engines was raised.
In the beginning, the suspension of the three compact O 302 versions still included coil springs at the front and trapezoidal leaf springs at the rear as standard equipment. Air suspension all round was standard on the large thirteen-row bus and the urban buses right from the start and was incorporated in the standard equipment of the other O 302 versions from 1971.
The O 302 was the first touring coach from Mercedes-Benz to feature individual nozzle ventilation for every passenger seat. Fresh air is drawn in at the front, over the windshield. And it was also the first to be optionally available with air conditioning, mounted in a box above the rear end. In coaches without air conditioning, passengers were able to protect themselves against the sun by means of retractable blinds. At his still rather sparsely equipped workplace, the driver had a genuine instrument panel in front of him – a flat panel extending from one side to the other, with only one set of gauges consisting of speedometer, rev counter and instrument cluster being slightly tilted toward the driver.
The history of the O 302 includes distinctive models. At the time, Daimler-Benz also exported buses to the USA, with the eye-catching stainless-steel paneling that was typical in the States. This paneling was optionally available for European O 302 units. The O 302 experienced a genuine highlight towards the end of its career: All teams competing in the 1974 World Cup in Germany traveled on O 302 coaches painted in their countries’ colors.
The world’s first hybrid bus
The O 302 also had a proper technical tidbit to offer in its day and age: In 1960, the world’s first hybrid bus – an OE 302 – was presented at the Frankfurt International Motor Show. The “E” in the model designation points to the additional electric drive. The conditions for a hybrid drive in the raised-floor O 302 bus are good because there is enough room under the floor for the equipment of a second drive system, including batteries. The direct-current traction motor had a continuous output of 115 kW (156 hp) and a peak output of 150 kW (205 hp) – power in abundance for an urban bus of the day.
The electricity for the traction motor was supplied by five battery blocks with 189 cells, a total operating voltage of 380 and a capacity of 91 kWh. A top speed of 70 km/h and a range of some 55 kilometers in regular service outline the limitations of the concept, as does the battery weight of 3.5 tons. For two-shift operation on a long regular-service day, the OE 302 was fitted with a 48 kW (65 hp) diesel engine adopted from the vans. This engine, transversely installed in the rear, was used to power the bus on the fringes of cities, operating in the optimum range at constant speed. An electric brake serves to recuperate energy.
More than 32,000 units built in eleven years
The versatile Mercedes-Benz O 302 was highly successful in many ways, also as a chassis. Renowned bodybuilders such as Ernst Auwärter, Drögmöller and Vetter tailored attractive bodies for the O 302 chassis. The O 302 was equally successful as an export item owing to its numerous variants – it was simply one for all! This had its effect on production figures: In the course of eleven years, Daimler-Benz built over 32,000 units, comprising chassis (a little over 50 percent) and complete vehicles – a world record. The successor, the O 303, reached a production volume that was higher still, but over a longer period.
The O 302 will remain clear record holder in annual output for the foreseeable future. The specialization of later years never permitted comparable unit volumes again.