Robert Bosch was apparently given the idea, to develop an injection pump for the Diesel engine from a friend. In his first engine, Rudolf Diesel already considered it necessary, to inject the fuel in a liquid form, indeed, because of the failing technical possibilities, wasn't able to do so.

The air-injection of Diesel fuel could however, only be realised in large engines. This is why since 1915, MAN, together with Saurer, only installed petrol engines in their trucks, as did all the others as well, Daimler had being doing it since 1896. In the first picture, part of the work done by Bosch's team, the injectors, can be seen.

They can be seen in more detail in the second picture, in the third picture, the injection pump is also added. Their development by the way, took almost as long as the development of the first Diesel engine did, 30 years earlier. The technical tolerances of one hundredth of a millimetre, which were necessary to be able to spray in one drop of fuel, at very high pressure, then have it evenly distributed to four cylinders and still be able to sensitively control the volume, were simply too demanding. Nevertheless, in 1927 the Bosch-injection pump matured into a finished product.

In the beginning, there were three companies who worked on the development of Diesel engines, because Daimler and Benz were still separate companies. Benz had already engaged the famous engineer and inventor, Prosper L'Orange, who was famous for his pre combustion chamber, that was still built for decades afterwards. Daimler still placed his bet on air-injection, which he gave up with the fusion of Daimler-Benz in 1926.

Technically seen, MAN, with their direct-injection, were in the lead, however, as can be seen in the first picture, with two injectors, the engine must have been a pretty rough and ready machine. It could be seen as proof, that much later, the M-procedure, with a type of pre combustion chamber in the piston was applied.

In contrast to the beginnings at MAN, the development was a world-wide success-story for Bosch, similar to his high-tension ignition and the spark plug. In 1928 they celebrated the delivery of the thousandth injector, and what's more, it could already be had for the Diesel-motor car. 07/14