For some, train books with pictures are like cook books with pictures: forget the technical stuff like tractive effort and wheel dimensions, ingredients and cooking time - just look at the pictures and drool. Among my favourite pictures are those are those of the Chapelon locos (see the picture below) that ran on the SNCF in France (Even as HO models, they look good.).

Chapelon's 4-8-4

To some they are ugly with all their American-style boiler excrescences; to me, whilst they are not beautiful in the sense that the British 'Pacific' Princess and Coronation classes are, there is a certain grandeur about them. It shouts "power" at you. It is claimed that Chapelon's 3 cylinder 4-8-4 242 A1 lays claim to being the "finest steam locomotive ever built". It had a tractive effort of 65,679 pounds - the most powerful in Europe. By comparison, the biggest British loco - the Coronation class - had a tractive effort of 40,285 pounds based on four cylinders - a 63% difference.(See below)

Coronation Class	Princess Class

Be that as it may, this article is not only about Andre Chapelon, as it was originally going to be, but on mechanical engineers whose names will be forever associated with railway locomotives in some way or other.

Whilst doing research on Chapelon, I came across a photo (see below) of a loco that compares in ugliness with Oliver Bullied's Q1. It was known as 'the flying pig'. One of the things that sticks out both literally and metaphorically about this loco is the valve gear. On steam locos, the valve gear directs steam into the front or back of the cylinder to move the piston, thus driving the wheels around. I could be wrong about this, but the valve gear on the flying pig looks like Walschaerts.

Bulleid's Q1	Ivatt's "Flying Pig"

Research on mechanical engineers whose names will be forever associated with steam engines, particularly with valve gear like Joy, Stephenson, Capriotti, Walschaerts, (and others) with locomotive design, like Chapelon, Bullied, Stanier, Fowler, Gresley and so on, and with boiler design like Belpaire and braking systems like that of Westinghouse, reveals that professionally they fall into two, possibly three, types. One type is where they started from the bottom, spent time in the system and then went onto to responsibility and consequently 'fame'. Another is similar, except that they did not start at the bottom, but about halfway up in a sense, mostly through professional training. A possible third mode in the British scene is through the workshops at Crewe, or Swindon or any of the other big railway centres - a sort of cadetship.

Alfred Belpaire (1820-1893) is an example of the professionally trained engineer. A Belgian by birth, he gained a diploma of engineering in Paris in 1840. Strait after graduation he became supervisor of the locomotive workshops at Malines. Ten years later he was promoted to director of the rolling stock department in Brussels. In 1864, he designed his famous square form boiler. Its purpose was to get better combustion from the poor fuels then available. (See Bullied's Irish experiment below.) This boiler design's square form allowed the use of horizontal and vertical boiler stays - a big improvement on what was then in use.

Egide Walschaert (1820 - 1901) was born in Malines, Belgium. The same age as Belpaire, he began his working life as a mechanic on the Belgian State Railways. He is an example of the first type mentioned above. By 1844 at the age of 24, he became foreman of the Brussels Midi station and works. In that same year, he invented his (now famous) valve gear. However, because the Belgian Railways would not let him receive royalties from his invention, it was patented by Fischer, Engineer of the railway system. His valve gear was first fitted to a 2-2-2 in 1848 and subsequently was used all round the world. The first use of Walschaerts valve gear on a British locomotive was as early as 1846, on a Fairlie 0-6-6-0, but it only really gained popularity in Britain the 1920s.

Andre Chapelon was of a later generation than Walschaert and Belpaire. He was born in France in 1892 and died in 1978. He graduated as an engineer in Paris in 1921 and by 1925 was in the research and development section of the Paris-Orleans Railway. He was recruited to find out why the Pacifics (4-6-2) of the POR could not better the performance of their Atlantic 4-6-0s. In 1926, he worked with the Finn Kylala and they jointly invented what became known as the Kylchap double blast pipe and chimney that significantly improved draft but minimised back-pressure.

However, it was Chapelon's work on thermodynamics that revolutionised steam locomotive design. He did not, however, start from scratch. George Churchward (1857- 1933) who became Chief Mechanical Engineer of the Great Western Railway in 1902 aged 45, did a lot of pioneering work on steam flow. He was articled at the age of 16 and therefore part of the group that did 'cadetships' and then went though the system and then to the top by promotion, but he knew his theory of steam propulsion. When he got the opportunity, he had three DeGlehn compound Atlantics delivered and put them through their paces for comparative purposes with simple expansion locos before the GWR abandoned compounds. He also combined the tapered boiler with the Belpaire firebox to great effect and also used large diameter long-travel piston valves and superheating to great effect. Chapelon revised some of Churchward's theories of steam flow and then expanded them. For example, he refined and enlarged the steam passages in a cylinder and by modifying valves he achieved a massive 50% increase in output from a 1929 design POR (Paris-Orleans) Pacific. Even though his 'mentor' Churchward abandoned compounding, Chapelon stayed with it. The result was his greatest achievement - the SNCF 3 cylinder compound 4-8-4 242 A1: "the finest steam locomotive ever built" unfortunately scrapped in 1960!

Caprotti valve gear was invented in 1921 by Arturo Caprotti, and was a type of valve gear known as 'poppet'. This means that the valves admitting steam into the cylinders are operated by cams on a rotating camshaft. Drive for the camshaft is taken from the driving wheels, by means of gears.

Arturo Caprotti was born in Italy in 1881 and died there in 1938. Like some of the others already mentioned, he was a graduate engineer, qualifying in 1904. After 2 years involved in car research and a further 2 years in other experimental work, he took on research into poppet valves in locomotives. His first Italian patent in this area was taken out in 1916 and applied widely from then on in the railway systems of many countries.

There are so many of these interesting men and their brilliant ideas and inventions that you could fill a book with them. In fact, just a study of British CME's of the big four railway companies (GWR; SR; LMSR & LNER) their loco designs and the way that they ran their engineering departments is enough to fill a book. Churchward (mentioned above) is just one example from the GWR. Stanier of the LMS is another; Gresley of the LNER is a third and Bullied of the SR yet another.

Oliver Bullied is interesting because most of the literature about virtually all of the other CME's praise them as great engineers and/or designers. Bullied is the only one to cop criticism - almost as if all the others are gods and he tried to be but failed. Bullied is also included here because like David Joy (1825-1903) and George Stephenson (1781-1848), he invented a valve gear system. Unlike them, his was good in theory, but not too good when it was applied.

O.V.S. Bullied (1882 - 1970) was a New Zealander, born in Invercargill in 1882. He went to the UK and worked on the Great Northern Railway under Henry Ivatt. By 1912, he was personal assistant to Gresley at Doncaster. (Gresley had succeeded Ivatt as CME.) In 1937 Bullied succeeded Maunsell as CME of the Southern Railway. During the Second World War (in 1941) he designed and produced the famous (infamous?) Q1 which included many novel features in its make-up.

Bullied designed the Merchant Navy Class and the West Country Class 4-6-2s. These locomotives used his self-designed valve gear, which was chain driven and oil immersed in a sealed case installed between the frames. It did not perform well, often leaking oil from the sump, which sometimes ignited, so from 1956 all 30 MN class and many WC class engines were rebuilt with Walschaerts valve gear. His last design for the SR was the Leader Class. They had so many design defects that they never saw service. In 1949 Bullied resigned from British Railways (the nationalisation of the big four was in 1948) and went to Ireland, where he was appointed CME of the Irish Railways. It was here that he designed a locomotive that used turf as fuel instead of coal. Oliver moved around a bit, because he died in Malta in 1970.

The British reward their citizens who have made a significant contribution to society in many and varied fields of endeavour with a knighthood. This allows the person to style himself "Sir". It is interesting to see how many British railway engineers were knighted for their work.

For example:

Sir William Stanier 1876-1965 (LMSR)
Sir Daniel Gooch 1816-1889 (GWR)
Sir Henry Fowler 1870-1938 (LMSR)
Sir Vincent Raven 1859-1934 (LNER)
Sir Nigel Gresley 1876-1941 (LNER)
Sir John Aspinall 1851-1907 (L&Y R)

*For a really interesting site that had working demonstrations of the major valve-gear, go to users.www.breathemail.net/defiant1/kerrstuart.html

Copyright © Peter Baddeley 2004