World's First Diesel Truck from Benz & Daimler in 1923
In 1923 Benz & Cie presented the first diesel truck to the world. The five-tonne vehicle was driven by a four-cylinder diesel OB 2 engine with an output of 33 kW (45 hp) at 1000 rpm. When compared with a petrol-driven truck of the same design, the efficiency of the diesel truck was immediately impressive: compared with the petrol engine, the diesel engine achieved fuel savings of 86 percent. Work on the new truck engine began in 1922. And in the September of that year the first major assembly was put on the test stand. Initially ten OB 2 engines were built.
First testdrives with the Benz Diesel Truck were done in the Northern Black Forest in September 1923. The first test drive was carried out in the challenging, hilly area around Gaggenau on 10 September 1923. The engineer's report assessed the vehicle as follows: "The favourable consumption is particularly impressive: supplied with brown coal tar oil, the OB 2 requires around 25% less than a petrol engine with the same power. The sensationally low fuel costs were due to the fact that the tar oil was cheaper than the petrol”
The Benz engineers chose the chassis on the Benz 5 K 3 truck which was designed for a payload of five tonnes. During the test drives, the OB 2 diesel engine proved itself to such an extent that on 14 April 1923 it was decided that the engine would go into series production. The prechamber OB 2 diesel engine was capable of an output of 37 kW (50 hp) at 1000 rpm.
In 1911 Daimler-Motoren-Gesellschaft began development of a compact diesel engine for commercial and agricultural purposes. While Benz & Cie. were developing the diesel truck, Daimler-Motoren-Gesellschaft in Berlin-Marienfelde was building an air-injection diesel engine to be fitted in a truck which boasted almost the same power. The finished product was a four-cylinder engine with an output of 29 kW (40 hp) at 1000 rpm. The engine proved its road capability during a series of test drives in 1923. The long-distance drive between the two DMG plants was particularly spectacular at the time: from 20 to 30 September 1923 a Daimler diesel truck drove from Berlin to Stuttgart and back. Following these tests which drew a great deal of publicity due to the then enormous distances, the first Daimler 5C commercial diesel vehicles produced in Marienfelde, a truck, a three-sided tipper and a bus were presented at the beginning of October 1923 at the Berlin automobile exhibition.
Following the merger of Benz & Cie and DMG in 1926, Benz's prechamber principle prevailed against the air-injection diesel engine. The first jointly developed prechamber diesel engine was the six-cylinder OM 5 engine from 1927 (55 kW/75 hp with a displacement of 8.6 litres). The abbreviation OM for diesel engines comes from "oil engine" and is still used today by Mercedes-Benz.