Diesel Engine (1893): Rudolf Diesel's Compression-Ignition Engine

The diesel engine is an internal combustion engine in which fuel is ignited by the heat of highly compressed air rather than by a spark. Rudolf Diesel’s first prototype ran at Augsburg in Germany on 10 August 1893, and within a few decades his invention had become the workhorse of shipping, railways and road freight.

Background: the search for efficiency

Rudolf Diesel was born in Paris in 1858 to German parents and studied engineering in Munich, where lectures on thermodynamics convinced him that steam engines wasted most of the energy in their fuel. Typical steam engines of the time turned only around a tenth of the fuel’s energy into useful work.

Diesel set out to build an engine that came closer to the ideal heat cycle described by the French physicist Sadi Carnot. He filed his patent application in February 1892 and set out his ideas in the 1893 book Theorie und Konstruktion eines rationellen Wärmemotors (Theory and Construction of a Rational Heat Engine).

The Augsburg experiments

Maschinenfabrik Augsburg, led by Heinrich von Buz, and the Krupp works in Essen agreed to fund development. On 10 August 1893 the first experimental engine, a tall single-cylinder machine, ran under its own power for the first time, if only briefly. The early trials were difficult: the extreme pressures strained the materials, and fuel injection proved hard to control.

After four years of redesign, a new engine passed formal tests in February 1897, reaching a thermal efficiency of around 26 per cent, far better than steam engines or the gas engines of the day. Diesel presented it to the Association of German Engineers in Kassel in June 1897.

How it works

In a diesel engine the piston compresses air alone to a high pressure, which raises its temperature to several hundred degrees. Fuel is then sprayed into the hot air and ignites spontaneously. Because there is no spark and compression is much higher than in a petrol engine, more of the fuel’s energy is turned into work, and heavier, cheaper fuels can be used.

Early engines used compressed air to blast the fuel into the cylinder, which made them large and heavy. Practical mechanical injection pumps, notably those produced by Bosch from 1927, made smaller, faster-running diesels possible.

Spread to ships, rail and road

Licences were sold across Europe and to the United States, where the brewer Adolphus Busch acquired the American rights in 1898. Diesel became very wealthy on paper, but heavy spending and poor investments left him in financial difficulty by the 1910s.

The first applications were stationary engines for factories and power stations. The Russian tanker Vandal, built for the Nobel brothers’ oil company, became one of the first diesel-powered vessels in 1903. The Danish Selandia (1912) was a landmark ocean-going motor ship, and diesel engines soon powered submarines in the First World War. Diesel trucks appeared in the 1920s, followed by diesel locomotives and, in 1936, one of the first series-production diesel passenger cars, the Mercedes-Benz 260 D. These built on the motoring age begun by the Benz Patent-Motorwagen and the mass production of cars such as the Ford Model T.

A mysterious death

On the evening of 29 September 1913 Diesel boarded the steamer Dresden at Antwerp, bound for Harwich and a meeting in England. He was not on board the next morning. About ten days later a Dutch boat crew found a body in the North Sea; they kept some personal items, which Diesel’s son Eugen identified as his father’s.

The disappearance produced many theories. Some claimed he was murdered by agents who did not want his engine used by the British navy, or by business rivals. Most historians consider suicide, linked to his debts and poor health, or an accident more likely, but no conclusive evidence has ever been found.

Myths and facts

• Myth: Diesel designed his engine to run on peanut oil. Fact: His engines ran mainly on petroleum fuels; a peanut-oil demonstration took place at the 1900 Paris Exposition on an engine built by another company.
• Myth: The 1893 engine was a success at once. Fact: It ran only briefly; a reliable engine took four more years of work.

Timeline

• 1858, 18 March: Rudolf Diesel is born in Paris.
• 1892, February: Diesel applies for a German patent on his engine principle.
• 1893, 10 August: The first prototype runs under its own power at Augsburg.
• 1897, February: An improved engine passes efficiency tests at Augsburg.
• 1898: Adolphus Busch acquires the American rights.
• 1903: The tanker Vandal is among the first diesel-powered ships.
• 1913, 29–30 September: Diesel disappears from the steamer Dresden.
• 1936: The Mercedes-Benz 260 D, one of the first series-production diesel cars, appears.

Why it matters

The diesel engine remains the most important power source for global shipping, heavy freight and many railways. Its efficiency transformed transport and trade in the twentieth century, while its emissions have made it a central issue in modern debates about air quality and climate.