The way things are today, I’ll leave you to decide whether the following story celebrates the 125th anniversary this spring of an invention which irrevocably changed the world for the good of mankind – or is a topic that really should only be discussed by consenting adults in private.

On 23 February 1893 the first of several patents were issued, outlining various  processes by which an oil-fired internal combustion engine might operate. The principles were described in a paper snappily entitled ” Theory and Design of a Rational Thermal Engine to replace the Steam Engine and Combustion Engines Known Today,” and the man behind both the paper and patent was Rudolf  Christian Karl Diesel, born in Paris of German parents on 18 March 1858.

GERMANY – JUNE 06: In 1892 Rudolf Diesel (1858-1913) patented a design for a new type of internal combustion engine. In 1897 he produced a 25 horsepower, four-stroke, single vertical cylinder compression engine, the high efficiency of which, together with its comparative simplicity of design, made it an immediate commercial success. Subsequent royalty fees brought great wealth to its inventor. He was lost overboard from the mail steamer ‘Dresden’ during a trip to London in 1913 and was assumed to have drowned. (Photo by SSPL/Getty Images)

Rudolf proved keen to learn, though his father’s modest income as a leather craftsman meant money was tight, making furthering his education difficult. Eventually he went to Germany, living with a relative who helped him achieve a scholarship to Munich Technical University. Graduating with a first in engineering, he gained employment with a refrigeration company, later returning to Paris, where he spent much spare time working on a more thermally efficient alternative to steam engines.

It’s not entirely clear when Diesel gained enough financial support to allow a move from refrigeration to full time development of his new engine, but despite several years of work, his first single-cylinder design was still untested when that 1893 patent was granted. Nonetheless, the principles embodied in his paper and patent are the same as those employed by today’s diesel engines: air is compressed by a piston inside a cylinder, generating heat, and fuel is brought into contact with the air at its highest temperature. The fuel then ignites, driving the piston downwards with great force.

After that first patent was filed, Diesel was taken on by German Engineering firm Maschinenfabrik-Augsburg AG – later Maschinenfabrik-Augsburg-Nürnberg, or MAN, still a familiar heavy truck nameplate. Here, much improved funding allowed development of a prototype single cylinder engine with 150mm bore and 400mm stroke – which was unsuccessfully tested on 10 August 1893. Around this time the Swiss engineers Sulzer brothers bought rights to Diesel’s patents, and began their own development process. 

More changes and improvements led to a string of further patents over the next few years, all relating to “an efficient, slow burning, compression ignition, internal combustion engine.” Diesel’s third prototype engine first ran successfully – almost five years after the concept was outlined – on 17 February 1897. This four stroke, water-cooled single cylinder device displaced 19.6 litres, and used compressed air to inject its fuel – peanut oil. On test, output approached 15kW (about 20hp) at 17.2 rpm, conclusively proving that the engine principle worked, and demonstrating an efficiency under load of 26.2%. This was a major achievement, since comparable stationary steam engines hardly bettered 10% efficiency. 

Sulzer also persevered: their first diesel ran 120 years ago in June 1898, the year  Rudolf Diesel gained his most important patent – no 608,845, for “an internal combustion engine.” Some of his early patents were however heavily contested, as a “hot bulb” engine type, fairly similar in concept, had run earlier. Ultimately Diesel won all the resulting patent battles, though contemporary reports suggested that the effort involved left him mentally scarred.

In the early years of the twentieth century, as practical diesel engines gradually emerged, the importance and far reaching potential of the new invention was quickly recognised. However available production techniques, sheer physical size, low rotational speeds and difficulties of getting fuel into the combustion chamber exactly when required prevented use of such engines in road vehicles. Where sheer size and peak power occurring at low revs mattered little, diesel engines were soon utilised as a steam power alternative – especially in ships, railway engines and stationary applications. Higher output, wide fuel tolerance and much lower fuel costs were seen as extra advantages.  

By 1908 Diesel was working with the Swiss Saurer company on development of faster running engines usable in roadgoing vehicles, but the limits of available technology prevented rapid progress. Indeed Rudolf Diesel never lived to see his invention take to the road – in a 1924 truck. By then he had been dead for 11 years – and to this day mystery surrounds exactly why he died. He had boarded a ferry at Antwerp, en route to London via Harwich, on 29 September 1913, took dinner on board and was never seen alive again. His body was washed up on the Scandinavian coast some days later.

The general belief is that he committed suicide. Despite acclaim and success bringing fame and fortune early in the twentieth century, several biographers suggest that by 1913 he was short of money, and that pressure of work, possibly combined with the mental stresses endured during his early and current engine development work, may have left his mind unbalanced. There are also at least two conspiracy theories: the Germans killed him to prevent sale of his engines to the Americans and the British; or his murder was arranged by powerful coal industry bosses in reprisal for sabotaging their burgeoning and profitable business…  

Rudolf Diesel’s legacy is so far reaching, it seems likely to be some time before mere government efforts to outlaw its emissions profile or tax users into submission – all based on current fuels – will have any noticeable impact. Diesel engines have answered so many questions for so long, particularly for heavy vehicle, rail and sea use, they have become inextricably woven into the fabric of human life worldwide. 

The continuing importance of Mr Diesel’s invention in facilitating travel and transport is irrefutable, but maybe its time to re-consider use of his original preferred (and sustainable) fuel. Has anyone done any particulate, NOx, and Co2 emissions testing on the use of peanut oil in a modern diesel engine by any chance…?

©Dave Moss


References and further information:

Rudolf Diesel Wikipedia entry;

Several biographies have been written. Few of them coincide in the overall story of Rudolf Diesel’s life… 

Here are some short/abridged versions:

Some notes on the early history of diesel engines are here. A fully detailed write-up is available from this page but requires subscription.

Very comprehensive information on the history and development of Diesel engines and other engine types can be found here:

The principal competitor to Rudolf Diesel’s engine design during the 1890’s was the “Hot Bulb” engine. It remained in use in some specialist applications into the early 20th century. More details on this engine type can be found here

Further reading:

 Rudolf Diesel’s book, The Genesis of Diesel Motors, was published shortly before his death in 1913.

 The German title is Die Entstehung des Dieselmotors”, Verlag von Julius Springer,

The full original version in German with charts and drawings is here as a PDF

Diesel Engines for Land and Marine Work (with an introductory chapter by the late Dr. Rudolf Diesel). A. P. Chalkley. 1917, New York: D. Van Nostrand Company, 1917 (earlier editions of this work were published)

Rudolf Diesel and the Diesel Engine. John F Moon.  1974. UK. Priory Press.

ISBN 978-0-85078-130-4, LCCN 74182524

Dave Moss
Dave Moss

Dave Moss has a lifetime connection with the world of motoring. His father was a time-served skilled engineer from an age when car repairs really meant repairs: he ran his own garage from the 1930’s to the 60’s, while Mum was the boss’s secretary at a big Austin distributor. Both worked their entire lives in the motor trade, so if motor oil’s not in Dave’s blood, its surely a very close thing.

Though qualified in Electronics, for Dave it seemed a natural step into restoring a succession of classic cars, culminating in a variety of Minis. Writing and broadcasting about these, and a widening range of motoring matters ancient and modern, gathered pace in the 1970’s and has taken over since. Topics nowadays range across the modern motoring mainstream to the offbeat and more arcane aspects of motoring history, and outlets embrace books, websites national and international magazines, newspapers, radio programmes, phone-ins and guest appearances. Spare time: hard graft on the garage floor attending to vehicles old and new. Latest projects: that 1968 Mini Cooper S has finally moved again after 30 years, and when the paint is finished, the 1960 Morris Mini 850 will also soon be ready for the road again…

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