Herbert Akroyd-Stuart was born on 28 January 1864 at Halifax, Yorkshire, England. He was the son of Charles Stuart, described as a machinists' modelmaker, and his wife Ann, née Akroyd. Akroyd-Stuart attended Newbury Grammar School, Berkshire, and the City and Guilds Technical College, Finsbury, where he assisted in the mechanical engineering department, and later worked in his father's Bletchley Iron and Tinplate Works, which he managed after his father’s death. Various experiments in engineering led Akroyd-Stuart to take out several patents. One day in 1885, he accidentally spilt oil from a paraffin lamp into a pot of molten tin. The oil vaporised, rose to the lamp and burst into flame. In his words: “That lucky incident … gave me a clear insight … as to what happens when oil vapour is commingled with air and ignited. Straight away, I began to think out a scheme … to design an engine to work on oil vapour.” Another patent (No.15,994) was taken out on 8 October 1890, which details the working of a complete engine where air and fuel are introduced separately. This patent stresses the importance of isolating the combustible charge in the combustion chamber, which is connected to the main cylinder by a narrow passage. Other patents followed, some jointly taken out with Charles Richard Binney. Their first really important patent was No 7146 of May 1890, entitled: ‘Improvements in Engines Operated by the Explosion of Mixtures of Combustible Vapour or Gas and Air.’ This patent describes the world's first compression-ignition engine.

Compression-ignition engine

[caption id="attachment_34000" align="alignright" width="215"]herbert-akroyd-stuart Herbert Akroyd-Stuart[/caption] The words of the patent describes how, after the combustion chamber or vaporiser has been externally heated by a blowlamp, "the induction stroke, which is the first outward stroke, instead of drawing into the cylinder a mixture of hydrocarbon vapour and air, simply draws in pure atmospheric air”. It continues: “The compression or first return stroke compressing this air into the pre-heated vapouriser, and at the desired part of this compression stroke, the supply of liquid hydrocarbon is forced, in a spray form, on to the heated vapouriser which almost instantly changes it into a gas, it combines with the heated air; automatic ignition takes place and propels the piston which forms the working or second outward stroke." The system is known as solid injection and is the principle used by most present-day diesel engines. Correct timing of the introduction of the liquid fuel ensures the prevention of pre-ignition. Ackroyd-Stuart maintained that he was the inventor of the compression ignition oil engine ahead of Dr Rudolf Diesel, whose German patents were taken out two years after Ackroyd-Stuart's and who produced a successful engine some seven years after the Hornsby-Akroyd. Akroyd-Stuart, MI MechE, constantly had to defend his invention against the name of semi-diesel when he claimed it should have been ‘Akroyd-cycle’. Modern oil engines use Akroyd-Stuart's method of oil-pump spray injection with constant volume burning in preference to the Diesel method of air-blast injection with constant pressure burning. Herbert Akroyd-Stuart was described as a courteous and gentle man who never married, although he was somewhat embittered by lack of recognition of his work. He died of throat cancer on 19 February 1927, aged 63, at his home in Yorkshire and was buried in the cemetery of All Souls Anglican Church, Halifax.

Building and development

coverRichard Hornsby & Sons was an engine and machinery manufacturer in Linconshire from 1828 until 1918. The company took the name of Richard Hornsby (1790-1864), an agricultural engineer. The company was founded when Hornsby opened a blacksmith’s in Grantham, Linconshire, in 1815. Richard Hornsby & Sons grew into a major manufacturer of agricultural machinery at its Spittle Gate Works. The firm produced steam engines used to drive threshing machines and other equipment such as traction engines: its portable steam engine was one of its most important products and the market leader. In 1891, the Hornsby brothers took the advice of their chief engineer Robert Edwards and agreed to develop and market a Hornsby-Akroyd engine on a royalty basis. Two of the Akroyd-built engines were exhibited by Hornsbys at the Royal Agricultural Show, in Doncaster, in June 1891. Akroyd had offered other engineering companies the option of manufacturing the engine, but they saw it as a threat to their business, and so declined the offer. Only Hornsbys saw its possibilities. Development on the Hornsby-Akroyd engine continued and in 1892, this work with Hornsby led to the world's first commercial heavy oil engines being made in Grantham from 8 July 1892. The first two engines worked regularly until 1923 (31 years), when No 101 was purchased by a Mr Evans, a Bletchley timber merchant. In 1939 (49 years), it was returned to Hornsbys, who restored it and preserved it as a museum piece. It was kept in the entrance to the Research & Development Department of Ruston-Paxman Diesels, at Lincoln, under the care of Ray Hooley, but it was apparently shipped to Germany following the takeover of the Ruston business by MAN group. The Hornsby-Akroyd oil engine was an immediate success. A total of more than 32,000 'hot bulb' engines were produced at Grantham. This was the start of more than 20 golden years for Hornsbys. It very quickly phased out all steam-engine building and pinned its faith completely on the internal combustion engine. Hornsbys was also very adventurous in the engine’s application. By 1896, it had produced the World's first oil-engined tractor and the world's first oil-engined locomotives. It also built engines for use in boats, submarines, lighthouses and radio stations. The company developed an early track system for vehicles, selling the patent to Holt & Co (predecessor to Caterpillar Inc) in America. After Akroyd-Stuart's patent elapsed, Hornsby made minor changes to the design and the result was that the Ackroyd was dropped and the engines became Hornsby oil engines. On 11 September 1918, when employing about 3,000 people, the company was bought out by Ruston & Proctor of Lincon to create Ruston & Hornsby.

The restoration process

[caption id="attachment_33998" align="alignright" width="300"]hot-bulb-engine The engine as found in Glencree[/caption] The hot bulb engine that is the subject of this article is a Hornsby Akroyd 9.5 hp, No 8,594 and it was originally sold on 19 November 1904 to T. Dockrell, Sons & Co Ltd of Dublin. It is not known what Dockerell’s used it for, but it is probable that they generated electricity until the city’s electricity supply improved sufficiently to sell on the engine. On 7 July 1913, it was delivered to Glencree Reformatory. In 2003, I was doing some work in the Glencree Centre for Reconciliation, a former army barracks and reformatory, in the Wicklow mountains 20km south of Dublin. I had a look in a shed and found what I thought was a green open-crank engine. The green was mould but, other than that, the engine was complete. My concern was that if the engine was left where it was, it would get damaged or scrapped. While dealing with public bodies takes time, I duly got permission from the late David Byres, the then Commissioner with Office of Public Works (OPW), and set off for Glencree to work out how to extract a hot bulb engine from a shed with only a domestic-size door. I arrived to find the engine stripped and several parts missing including, most importantly, the valve chest and the injection pump. However, I had undertaken the challenge and decided to carry on. When I got the engine to my workshop, there was a considerable quantity of rust that had to be removed; this was done with the aid of reverse electrolysis. Many of the nuts and bolts had been replaced with post-WWII items that were of a smaller size. Apart from stripping down, cleaning, painting and re-assembly, the main part of the work was making replacement nuts and bolts. I carried out the main part of the restoration in 2005/6, but I was still left with the problem of the missing parts. Eventually, I sent out an appeal on a national radio station, as I supposed that whoever had taken them knew A) what they were and B) that the engine had been removed from Glencree. The next day, I got word that I could collect all of the parts from a workshop nearby. The vaporiser was now the only part missing and this was donated to the project by Richard Hopkins of Bristol, subsequent to placing an advertisement in Stationary Engine magazine. Technical advice was also obtained from Geoff Chandler of the Anson Engine Museum near Manchester.

Completing the project

S [caption id="attachment_33999" align="alignright" width="300"]hot-bulb-engine The engine during restoration[/caption] tart-up day was a nervous one. I had never restored a hot bulb engine before, being more familiar with the, innards of my Velocette Venom engine. It took a bit of time to figure that the best way to start it was to use a backfire to make it go forward. To celebrate the restoration, we held a party in the workshop and took the running engine on tour to Shane’s Castle Steam Rally in Stradbally, Co Laois and Moynalty Stream Threshing Festival, Co Meath. I could not have undertaken this project without the help and encouragement of many other engine enthusiasts and many friends, especially Declan Byrne and Ross Galbraith. Particular thanks go to the late David Byers and Dermot O’Brien of the OPW (the owners), to Tommy Peate for lifting and transporting, Seán Cullen for finding a lathe and tooling and Tim Murphy for the long-term loan of the garage crane. To Rachel McNicholl for putting up with my obsessions, to Radio Éireann’s Brenda Donohue and Derek Mooney for broadcasting my appeal for the missing parts and last, but not least, to Peter Stopford who gave me endless help and advice.

Fiacc O'Brolchain is an architect with a strong amateur leaning towards engineering.  Over the years he has been involved with rebuilding projects that include a 210hp two-stroke diesel engine, several vintage motorcycles and many sailing vessels.  He has also worked or advised on most of the small water turbines that are still in operation in Ireland along with designing new small hydro stations.  Fiacc has a one-man architectural practice and has run a consultancy, Water Power Services, since 1981.

Author: Fiacc O'Brolchain is an architect with a strong amateur leaning towards engineering. Over the years, he has been involved with rebuilding projects that include a 210hp two-stroke diesel engine, several vintage motorcycles and many sailing vessels. He has also worked or advised on most of the small water turbines that are still in operation in Ireland along with designing new small hydro stations. O'Brolchain has a one-man architectural practice and has run a consultancy, Water Power Services, since 1981.