One Hundred & TEN Years of Desmo-Patenting : A Factual Summary

All people (not only kids) seem to like statistical data and the answers to questions like: which one was the oldest, most important and famous (desmo-patent) ever.
In this concise article about DVG (Desmodromic Valve Gear), I will try to satisfy as much as I can of your curiosity and information needs. But I understand also that I could fill a whole tome to cover all the material I have collected over the years. More questions might come up and their answers have to be postponed to a later date and put in another form.

About the Desmo-Principle

“Desmodromic” motion control (in design of machinery) is hundreds of years old. Also in steam-engines (excenter-type movement) we very often see valves controlled this way. In many hundreds patenttexts the word "desmodromic" is used in patents for time pieces (watches), valve-control in piston pumps, gear-shifting units, film-transport movement, weaving looms, steering gear, vibrating-, folding- and wrapping machines etc. etc.
"Desmodromology" is about desmodromics in Internal Combustion Engines only.

Who possesses the most hard-copy desmo-patent documents in the world?

OK! I don’t want to bother you about when and how I started (30 years ago) painstakingly collecting the desmopatents, but I have them all. Almost, because “absolutes are unobtainable” and there is always a grayhaired area and there are always arbitrary and aberrating in- and excluding criteria. Not to mention people making mistakes in classifying the documents. Today everybody (with an internet connection) can have easy access to patents in open source databases like espacenet and download their own copies in PDF and make prints.

The first desmo-patent

F.H. Arnott is supposed to be the owner of the first desmo-patent (1910) (group 1A-system), but I didn’t find the evidence. The application was abandoned before publication and the original documents would have been destroyed.
Actually I digged up other / earlier patented systems like Nash (1884) a group 10 excenter system, but also Hider and Secor (both 1898) and both Group 1A-systems!
Please see also Arnott and Hider in "Patented Systems":
But of course the Daimler engine using a cam groove system was even older (patent DE50839; 1889-06-09).

Oldest desmo-patent in 4-stroke Internal Combustion Engines

Perhaps the system of Lewis H. Nash (application filed 1884) is the first to mention. See also:

The first use of the word “desmodromic” in patent-texts

is probably in the title of the Swiss patent nr. 6911 dated 1893-04-01 from Claude Bonjour: ‘Mécanisme hydrostatique desmodromique pour la commande des organes de distribution .... etc." Or perhaps even earlier in a possible French equivalent patent of this invention.
The German word ‘Zwangsläufig’ (controlled run) is used many times in patent-texts before that date. Actually it is this word that was used by Franz Reuleaux in his textbook about kinematics (1875) and that was creatively translated by an Italian translator in ‘desmodromico’. OK enough about word roots…

The most famous patent

of course must be the Ducati patent assigned to inventor Fabio Taglioni (alias Papa di Desmo).

The most important patent

is probably the Ducati patent assigned to inventor Massimo Bordi and Gianluigi Mengoli.

The size of patent-documents

varies from one single text page and 1 figure(page) in the early days up to 31 pages for a desmopatent (US6053134) and to 53 pages for a desmo-patent application (WO0012873) in Y2k.
Mr. Gerald Williams’ patent CA 1149750 (IPC: F02B 75/04) with Desmo subclassification beats everything with 160 pages.

The classification

in the early days was straightforward, but differing from country to country, composed of one class and one subclass like:
in Germany: Klasse 46b Gruppe 2
in France: Gr.5 Cl.8
in GB: Cl. 7(2)
in US: 123/90.25
Today in the used classifications (IPC and EOB) only one patent application can show up to 7 different (sub)codes.
I found a total of 28 (sub)codes combined with the IPC desmocode F01L1/30 (not in one patent of course). Mechanical desmo combined with: hydraulic; pneumatic; electric; changing compression; V.V.T. ; in and out switching of valve; sleeve valve etc.
Example: Roger Arlaud FR2702003 ‘Dispositif de commande electrohydraulique ….’ IPC :F01L9/02 ; F01L1/30 ; 1/34 ; 1/00 ; F02F1/24 ; EOB F01L3/20; F01L9/02
Nb The following discussion is limited to mechanical actuated cam/valve systems of conventional/traditional definition and not the divergent combinations from above.


Unique or not unique, that’s the question:
525 unique systems in one hundred and ten years means an average of only about 5 systems per year.
Is it common that for a single IPC-code, patent applications run for such a long period of time?

The number of produced systems with DVG

is greater than 70. See also:

The number of systems protected by patent or patent-pending

is greater than 20.

Most critical desmo-year

is 1985, because almost the (Big) End of Ducati, when nearly bankrupt and the Castiglioni brothers (Cagiva) saved the principle. After that year we saw a great upheaval with the 4-valve engine and with great results.

New phenomenon

A complete website created (Y2K) and posted to market an invention: Meanwhile a dead link.
Later example: Inventus Engineering (Austria)

Roaring Twenties

All types (except one) from our classification were known/invented before the end of the twenties of the past century! For understanding the groups please consult : classification.html

List of First Known Patents for Each Classification (sorted by group)

0(Zero) 1929GrayUS
1A(1)(mixte) 1910SharpGB
1A(1)(direct) 1911Stas de RichelleBE
1A(3) 1913MillerGB
1A(4) 1921HolleUS
1B 1930JunkDE
2 1905KruppDE
3 1908NeerUS
4 1912KellyUS
5 1913MichauxFR
6A 1913JanvierFR
6B 1912KruppDE
7A 1905Nürnberger Motorfahrzeugfabrik "Union"DE
7B 1911KruppDE
7C 1926AndersonUS
8A 1916ChevroletUS
8B 1919Cattaneo*IT
9 1926DuboisFR
10 18.."Plenty""Plenty"
11 1923BernardFR

* Fiat already in 1913 had a beautiful Group 8B system, but probably (because of WWI?) never patented.

List of First Known Patents for Each Classification (sorted by year)

first Kown Patents for
each Classification
Till 1900 10
1905 2 and 7A
1908 3
1910 1A(1)[mixte]
1911 7B
1912 4 and 6B
1913 5 and 6A
1919 8B
1920 8A
1923 11
1926 7C and 9
1982 8C*

* This means that only one new system was presented after the twenties:

List of First Known Patents for Each Classification (sorted by country)

First Known Patents
Per Country
AU 1x
DR/DE 5x
FR 4x
GB 1x + [1x 1A(3)]
IT 1x
US 4x + [1x 1A(4)]

Two major continents compared

EU versus US = 11 : 4

Did someone ever invent more than just one group-representative?

It is a remarkable fact that the German firm named “Krupp AG” invented 3 different classification group-representatives.

Car versus Motorcycle Industry : a Comparison of Desmo Patenting Activities : Distributed between the Consumer Car and Motorcycle Industry

The car-industry also was at times interested enough in the DVG to submit patents for their inventions: The hereunder mentioned Marques asked for one or more (unique) patents. Nb [number(s) and period of time not too exact].
Nb In the case of Honda and Suzuki (they are combination of motorcar and motorcycle manufacturers), there is evidence that the inventions were intended and meant for a motorcycle engine.

Number of Patent(applications)
Per Car Manufacturer
NumberYear or Period
AUDI 121986-1993
FORD 21984-1986
JAGUAR CARS 21988-1990
MAZDA 11990
MITSUBISHI 31978-1984
NISSAN 71978-1990
PORSCHE 41958-1978
VOLKSWAGEN 51977-1987

Number of Patent(applications)
Per Motorcycle Manufacturer
NumberYear or Period
DUCATI 31956 + 1987
HONDA 111983-1985
NORTON 31920-1922 + 1957
SUZUKI 21984 + 1992
YAMAHA 11993

Facts & Conclusions

In the early days desmopatents were often granted to race-car manufacturers.

In the eighties and nineties several car-manufacturers were apparently seriously involved in the DVG-principle, but with no noticeable results. We can only guess the reasons for this: Calculation, marketing and maintenance aspects and perhaps also considerations of patent infringements (jurisprudence about patent offences or any reservation caused by patent-protection?).

Future of the DVG-principle (still alive and kicking?)

The first GP car with DVG [meant to win a GP also?] was the Mercedes-Benz W 196 in 1954 (Guinness book of cars facts and feats), but you could also go for the (not a winner) 4,5 L DOHC Delage GP-car in the 1914 Lyon GP?
(G. Borgeson)
There were also some motorcycle manufacturers like Norton and Velocette (BMG) interested in DVG, but Ducati was and remained the only manufacturer of desmo-production engines in the MarketPlace. Today, all their models feature a desmo-system.
After 13 years of production of the liquid cooled 4 valver resulting in 5 world championships in the SuperBike class, Ducati released in 2001 a completely restyled (Testa Stretta) desmo-head giving it a new world championship title.
Ducati takes since 2003 and still (2012) part in the MotoGP scene with the Desmosedici with immediate and fantastic results:
Poll positions; podium places and already a first place in the Spanish GP in Catalunya for Loris Capirossi.
Last not least the Desmosedici made the fastest speed ever on a GP circuit.
With 332,4 km p/h it went faster than Michael Schumacher's Ferrari.
This means that after half a century the desmo-principle is back again on the highest level of Competition and Technology! Will it ever become available on the consumer car market?

Duds that makes you nuts

I found quite some bureaucratic mistakes in the classifying activity of examiners and other patent office clerical workers:
Entered to the EOB-Inve(ntory) as F01L1/30 the following numbers are definitely and sometimes explicitly non-desmo:

Non-desmo patents
per country
DE 143181Deutz1902
DE 667509Tebaldi, Alessandro1938
DE 2621363Daimler-Benz1977
DE 3926809Kriegler1991
DE 4210765Daimler-Benz1993
FR 746700Bach$#232;re1933
GB 1139657Giles1969
GB 1325480Lester1971
GB 2340881Olsfanger2000
US 901363McGarty1908
US 1724707Wesley1929
US 2015135Bradey1938
US 4041838Warren1977
US 4530318Semple1985

A Desmodromic Mind, something to worry about?

These several hundreds of facts and pieces of information have become known to you, because someone was “autistic” enough and an armchair scholar also, to go after them and to present them in this article, published through this fantastic cyberspace medium.
This adventure in the physical world helped me to bring my religious mind at ease after too much idealistic, political, sociological and philosophical work. And I really enjoy(ed) this position on the Maslow Pyramid.
Of course I know there are philosophic questions left over, we will never be able to answer like:
How much energy and money went into this technical principle?
How much sorrow and how much joy did it bring to man?
How pro- and contra-survival was / is this principle?
How much time will be left to me to further discover this body of knowledge and follow its achievements in the real world? Who cares?


Amount of published patents per group

Amount of unique individual patents per country

Amount of unique individual patents per timespan (decennium)

Copyright by Henk Cloosterman, March 2012