Mercedes-Benz W 194

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The Mercedes-Benz W194 is only in the year 1952 under the name Mercedes 300 SL inserted racing cars from Mercedes-Benz .

Like the street car of the same name sold from 1954 (but with the type designation Mercedes-Benz W 198 ), it was built and used both as a coupé with gullwing doors and as a roadster .

Development for 1952

Mercedes-Benz 300 SL from 1952 in " Carrera Panamericana " version in the Mercedes-Benz Museum

In 1951, Daimler-Benz CEO Wilhelm Haspel had international motorsport observed very closely. After test race resulted with the 12-year-old pre-war models in South America whose unfitness for current contests, fell in the Daimler-Benz Board's decision, although not yet in 1952 the Grand Prix (now the F1 to compete designated), but at least in important sports car races participate , and to build a racing car for this, which was named "300 Sport Leicht". For this purpose, the existing drive train of the 300 series sedan ( W 186 ) was further developed and built into a newly developed body.

The sports engine developed for the M 194 differed from the “civil” three-liter six-cylinder in-line engines not only in terms of output (increase from 115 hp / 85 kW to 170 hp / 125 kW), but also in a special feature: it was built at an angle built in inclined from 50 ° to the left (half lying). The four-speed gearbox connected to it, also taken directly from the 300 sedan, was robust, but - like the engine - not exactly light. In terms of weight, there was nothing that could be done about the weight of the engine and transmission of the maturing W 194. The axles also taken over from the 300 were made of steel. So the search was aimed at other potentials for weight reduction and speed increase. Depending on the situation, they could only be found in the frame and body, and in a structure that was as streamlined as possible. Rudolf Uhlenhaut , Head of Car Testing at Daimler-Benz, took up his idea of ​​a lightweight tubular frame that he had been working on a few years earlier. His designers developed this idea to its completion. The result was a light, extremely torsion-resistant tubular space frame, composed of very thin tubes into lots of triangles, the elements of which were only subjected to compression and tension in the sense of a " K-framework ". It weighed only 50 kilograms and became the trademark not only of the W 194 and the series version presented in 1954, but also of the successful racing and racing sports cars of 1954/55. The 300 SL weighed only 1,100 kg instead of the 1,780 kg of the 300 S.

Due to the inclined engine and the desired wind slippage, the car body was very low, straight to the underbody, with a flat nose, aerodynamically shaped curves, retracted headlights and wheels fully covered by the body. As in the prewar period, the classic Mercedes-Benz radiator with a star as a hood ornament was dispensed with in favor of a flat racing car front - but not the Mercedes star, which was now large and clearly visible on the grille of the cooling air opening. The coupé attachment was as narrow as possible. The windshield was clearly sloping and rounded towards the A-pillar; elongated, the large rear window merged into the streamlined, rounded rear. The result was a relatively small frontal area of ​​1.8 m² and an excellent c W value of 0.25.

In order to give a tubular space frame high stability, it must be designed as wide or high as possible in the area of ​​the passenger cell. In the first vehicles, the door cut-out began above the belt line and was so small that it was extended to the roof, and with doors opening upwards, the spectacular, later so famous, double-wing doors. When both were open, they were reminiscent of outstretched wings, christened "Gull Wings" by the Americans, and "Papillon" (butterfly) by the French. The driver and front passenger got in from above rather than from the side. In order to be able to cope better with the entry via the high side wall, there was an entry step in the lower part of the body flank.

The interior was fully clad and exuded a comfort that was unusual for a racing car. The speedometer and tachometer were under the same hood, and below that, the instruments for water temperature, fuel pressure, oil temperature and oil pressure were somewhat smaller. Even a stopwatch was installed. The high-sided bucket seats had thin, yet comfortable upholstery made of checked wool. The four-spoke steering wheel was removable to facilitate entry. The long, angled gearshift lever protruded from under the dashboard, the “cane” handbrake was arranged flat on the left side of the ship. At that time there were no headrests or seat belts, power steering was reserved for luxury sedans.

The original 300 SL, chassis number W 194 010 00001/52, completed its first test drives in November 1951 on the Solitude race track at the gates of Stuttgart, on the Nürburgring and the Hockenheimring . The car still had narrow series tires on steel wheels without a central lock, but with hubcaps. The dashboard was not yet covered, the footwell without velor trim and the Mercedes star and 300 SL lettering on the trunk lid were not yet in their final place.

On March 12, 1952, the Mercedes-Benz 300 SL racing coupé, which is unusually smooth and low - it was only 1225 millimeters high - was presented to the press on the A81 motorway between Stuttgart and Heilbronn.

Racing successes

Carrera Panamericana, Mexico 1952 - Karl Kling and Hans Klenk after an accident with a vulture

In 1952 the vehicle took part in important sports car races of the year.

For the first time, the new SL demonstrated speed and reliability at the Mille Miglia at the beginning of May and achieved second and fourth places in this endurance race.

A triple victory was achieved at the Bern Prize in Bremgarten. The racing car unexpectedly ended the Le Mans 24-hour race in 1952 with a double victory. The winners were Hermann Lang and Fritz Rieß with an overall average of 155.575 km / h, a new record in Le Mans history. Second were Theo Helfrich and Helmut Niedermayr. A race at the Eifelrennen at the Nürburgring also ended with a triple success. At the end of the year, at the Carrera Panamericana in Mexico , the 300 SL unexpectedly won again. In this way, Mercedes-Benz built on the great successes in racing before the Second World War .

Further developments in 1953

Mercedes-Benz 300 SL prototype 1953

In 1953 further improvements were tested on prototypes. The partially revised body was now made of sheet magnesium, which is even lighter than aluminum. In the wind tunnel, thanks to an optimized shape, especially in the bow area, it not only gained a new face, but also improved airflow through the engine compartment. The waste heat from the engine no longer got through the cardan tunnel to the rear, but more aerodynamically on a short route through "gills" in the fender to the outside. The engine output also increased. Thanks to new flat-flow twin carburettors from Weber , a new cylinder head with larger ducts and even larger valves, the six-cylinder achieved the desired 200 hp. It was exactly 201 hp. The adjustment ( synchronization ) of the three carburettors was complex, and so the developers were not yet satisfied. They wanted more reliability.

The solution to the problem was gasoline direct injection . The application of this technology turned out not to be too difficult for Daimler-Benz due to the experience gained from 1934 in the development of aircraft engines ( Daimler-Benz DB 601 ). In the version planned for 1953, the 300 SL engine - after the small Gutbrod Superior and Goliath GP 700 E one of the first cars with gasoline direct injection - offered 215 hp and was internally called the M 198 . The special thing about it was the direct injection into the cylinder, which was developed at the time for aircraft engines. From 1957 onwards (first in the Mercedes 300 ) they switched to intake manifold injection, because direct injection caused problems with oil dilution and the injection pump was also very complex to manufacture for the higher pressure required . In passenger cars with gasoline engines, direct injection was only available again in the Mitsubishi Carisma  GDI from 1997 . In the M 198, the injection nozzle was not located in the cylinder head , as in current engines , but in the cylinder wall and sprayed diagonally upwards against the exhaust valve. This cooled it and supported the evaporation of the fuel. The injection nozzle was passed over by the piston rings and was thus protected from the worst possible exposure to the hot fuel gas.

The cylinder block of the M 198 is made of an aluminum alloy . The gearbox and fuel tank were also made of light metal. To put more weight on the rear axle, the wheelbase should be shortened and the gearbox, oil tank and battery should move to the rear. The suspension points for the rear axle were lower; the swing arms led directly to the wheel hub.

successor

From 1954, the 300 SL road car ( Mercedes-Benz W 198 ) was sold, first as a coupé with gullwing doors , then as a roadster .

The successor as a racing car, which is based on the Formula 1 type Mercedes-Benz W 196 and had an 8-cylinder engine, was only used in 1955 under the name Mercedes-Benz 300 SLR .

literature

  • Markus Bolsinger, Jürgen Lewandowski, Harry Niemann: 50 years of the Mercedes-Benz 300 SL . Delius Klasing Verlag, Bielefeld 1992, ISBN 3-768-81512-9 .
  • Jürgen Lewandowski: Mercedes 300 SL . Suedwest Verlag, Munich 1988, ISBN 3-517-01101-0 .
  • Günter Engelen, Michael Riedner, Hans-Dieter Seufert: Mercedes-Benz 300 SL . Motorbuch Verlag, Stuttgart 1999, ISBN 3-613-01268-5 .
  • JA Hofelich: Mercedes 300 SL. The dream car from Stuttgart . Podzun-Pallas-Verlag GmbH, Friedberg 1992, ISBN 3-790-90152-0 , ( Auto-Classic 5 ).
  • RM Clarke: Mercedes 190/300 SL 1954-63 . Brooklands Books Ltd, Cobham 1988, ISBN 1-870-64226-0 , (en).
  • Robert Ackerson: Return to Glory! The Mercedes-Benz 300 SL Racing Car . Veloce Publishing, Dorchester 2013, ISBN 978-1-84584-617-6 (English).

Web links

Commons : Mercedes-Benz W 194  - Collection of Pictures, Videos and Audio Files