The 75th anniversary of diesel fuel injection is just a month away. On 30 November 1927, Bosch embarked on the first ever large-scale production of diesel injection pumps and injectors, which allowed engine manufacturers to viably mass-produce small fast-turning diesel engines for the first time. They were used in trucks and buses then later in passenger cars.

Prior to 1927, diesel could only be used for large stationary engines or ship’s engines produced in small numbers because fuel had to be squirted into the combustion chambers by means of a separate compressor – an expensive and inefficient system. It was not until the pre-chamber combustion process was invented in the early 1900s that the potential of diesel could start to be realised.

In 1921, Bosch began experimenting with diesel injection systems and, by 1924, was able to test prototype diesel injection pumps. In March 1927, Bosch decided to produce a limited run of injection pumps for engine manufacturers to experiment with. In just six months, these tests confirmed the viability of the pumps for mobile engines and Bosch started large-scale production on 30 November.

The first customer to use the new injection pumps was the German company M.A.N., which put a new system in some of its trucks. After this, things really took off and within a year Bosch had sold its 1000th pump. By March 1934, the 100,000th pump had left the production line.

The next great milestone for diesel was the launch of injection pumps for passenger cars in 1936. With continuous development, Bosch had succeeded in producing injection pumps that were light enough and strong enough for the relatively high-revving car engine.

The so-called compression ignition engine has since become a familiar feature of passenger cars, buses, trucks and vans, and today, more than a third of all passenger cars registered in western Europe are equipped with a diesel engine.

In terms of modern motoring, a major step forward was made with the first direct injection system in the 1989 Audi 100 TDI, which used an electronically controlled Bosch axial-piston pump. This set the trend and Bosch soon followed this up with new high-pressure direct injection systems: the VP44 radial-piston pump in 1996, the accumulator system known as Common Rail in 1997 and the unit-injector system in 1998.