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Feb 7, 2007
- Fuel-efficient engine design for a period of economic difficulty
- Multi-purpose chassis – suitable also for buses
- Diesel technology’s breakthrough in the field of commercial vehicles
At an extremely difficult time, Daimler-Benz AG dared to take the step of extending its commercial vehicle range further than ever before by, for the first time, offering a diesel engine as standard in the so-called high-speed truck. The light-duty truck was called Lo 2000, was fitted with the newly designed 3.8-liter OM 59 pre-chamber diesel engine, and it helped the compression-ignition engine to become widely accepted.
The turn-around comes with the Lo 2000
The world was turned completely upside down. Daimler-Benz AG’s extensive – and unprecedented – modernization and diversification of its truck range had been preceded by inflation, world economic crisis and political upheavals. The widespread crises had not, however, left Daimler-Benz unscathed. Truck buyers were thin on the ground. Whereas in 1928, commercial vehicle production had totaled 4,692 units, in 1932, only 1,595 vehicles left the factory in Gaggenau. This plant had been given responsibility for the manufacturing of commercial vehicles by Daimler-Benz AG, which had come into being through the merger of Benz & Cie. and Daimler-Motoren-Gesellschaft in 1926.
More than 13,000 units produced
When Daimler-Benz presented the new Lo 2000 two-tonner (designations at that time related to the payload) at the Geneva Motor Show in 1932, none of its fathers would have dared predict that this model would reach unit figures of over 13,000. The new OM 59 diesel engine played a crucial role in the success of the Lo 2000, a model which the customers quickly came to value as an economical truck of great efficiency.
Even in the field of heavy-duty trucks, the new technical achievement of vehicle diesel engines was, at the time, no matter of course. However, while in the USA, for example, gasoline engines were still commonly found under the hood even into the sixties, people in Europe, in the wake of the world economic crisis, had become aware of the advantages of the economical diesel engine and used it increasingly.
Outstanding economic efficiency
The very first test drives with a Benz prototype in 1923, a year haunted by inflation, had demonstrated how much of a saving the diesel engines could make: “Fuel consumption is around 25 percent lower than in our normal, benzene-driven trucks,” the pioneers rejoiced. In practice, this meant a reduction in fuel costs of more than 80 percent since at the time, the duty- and tax-free gas oil was a lot cheaper to buy than gasoline for carburetor engines.
And yet the use of diesel technology for vehicle engines was still small-scale in the early thirties. The first production trucks with pre-chamber diesel engines, which took the form of Benz five-tonners, had made their debut in 1924 at the Commercial Vehicle Show in Amsterdam. However, it was to take until the invention of the injection pump for the diesel engine to make an initial breakthrough in the field of heavy-duty trucks.
Bosch’s pump was already put to use in 1927 in the 8.4-liter OM 5 diesel engine with 70 hp, which, between 1927 and 1929, was sold a total of around 2,000 times in the L 5 five-tonner. Up until 1931, the percentage of diesel engines had quickly risen to ninety percent in trucks of five tons or more. And from 1934, Daimler-Benz produced trucks with a payload of five tons or more with compression-ignition engines exclusively.
“Diesel” logo conspicuously on display
More propaganda work was, however, still required as far as the light-duty trucks were concerned. The OM 59 presented strong arguments: less than half the size of the OM 5, but almost equally powerful, the compact 3.8-liter 55-hp diesel engine made its debut in the new Lo 2000 light-duty truck model which reached a top speed of 65 km/h. And through this, it did great credit to its name “high-speed truck”. And consequently the diesel engine also became widely used in smaller truck models. Below the three-pointed star, positioned across the radiator grille of the Lo 2000, an enormous “Diesel” logo proudly announced the latest achievement.
Easily maneuverable, fast and economical, the vehicle was well received. Its versatile design allowed it to be used as a dump truck, removal van, tank or refrigerator truck and also as a purpose-built vehicle for the local authorities, police and fire service. The Lo 2000 also proved to be suitable for use as an ambulance right from the start. From 1934, the first semitrailer tractors complemented the range.
The new high-speed truck was an all-rounder in the true sense of the word and, from the start, was intended to be as widely applicable as possible. Daimler-Benz had designed the chassis as a compromise between high and low frame so that the so-called semi-low frame design with slightly offset side members was suitable for both bus and truck. The small “o” in the model designation refers to this characteristic.
The engine’s dimensions were the same as those of the carburetor variant in the Lo 2000, which continued to be used a great deal, especially in export. The two models also produced identical values in terms of performance and top speed, making it possible to use the same transmissions and axles in both. With such practical details as a split cylinder head and a removable set of pre-chamber, nozzle and cartridge, the diesel engine in the Lo 2000 introduced a new phase in design.
Increase in payload, additional diesel engines
It was therefore only logical that Daimler-Benz would promptly develop this convincing design for higher weight categories. Slowly but surely, the Lo family increased its number of models with higher payloads and more powerful engines. The four-cylinder engine grew from 3.8- to 4.9-liter displacement and was finally complemented by a six-cylinder version with 7.4-liter displacement and a proud 95 hp.
When in addition to this, in 1936, Daimler-Benz had presented its first diesel-engined passenger car to the world, the latter's 45-hp 2.6-liter diesel engine made its entrance the very same year in the new L 1100 to L 2000 series, produced in Stuttgart and Mannheim. These vehicles were designed for light-duty tasks and can be seen as the forerunners to the modern van, even if the L 1100’s hood design does create quite a different visual impact.
Encroachment upon truck design
The diesel engine had set out to conquer the light-duty commercial vehicle segment and was not to be stopped in the long term – even though politics radically interfered in the course of the 1930s. From 1938, the Nazi dictators imposed a tight regime on the entire motor vehicle industry. Under the so-called Schell Plan the Nazis limited the number of basic truck models to just four, and the manufacturers had to build what the dictators asked for. Trucks with payload ratings of three, four-and-a-half and six tons were allocated to Daimler-Benz. For the light-duty trucks of Daimler-Benz, the verdict meant that these had to be powered by gasoline engines again to meet the armed forces’ requirements.
With armament taking priority over everything else, trucks became scarce commodities for the civilian sector. As early as 1936, those in power had forced all commercial haulage operators to have themselves and their fleets registered. When the war began in September 1939, the armed forces confiscated some 8,000 of the 15,000 trucks operated in the German Reich at the time and drafted most of the drivers as well. From October 2, 1939, private buyers were no longer granted a permit for the acquisition of trucks if they were unable to prove that these were urgently required in conjunction with the war effort.
For detailed information on the diesel history of Mercedes-Benz please click here