NOTE: This article was written by Ray Hooley and made available to various publications some years ago. It is included here to give additional information on the Akroyd engine and its inventor, Herbert Akroyd Stuart.
Herbert Akroyd Stuart was born in Halifax on the 28th January 1864. His father, Charles Stuart Akroyd was a Scotsman from Paisley, who established the Bletchley Iron & Tin Plate works at Bletchley, Buckinghamshire. After working for a short time as a Junior assistant in the Mechanical Engineering Department of the City & Guilds of London Technical College, Finsbury, London, Herbert joined his father at Bletchley and immediately commenced experimenting with oil engines.
His first patent was taken out in 1886. Others followed, 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.
It 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. 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 used is known as solid injection, and is the principle used by most present-day diesel engines.
Patent No 15994, of October 1890, stresses the importance of isolating the combustible charge in the combustion chamber which is connected to the main cylinder by a narrow passage. Correct timing of the introduction of the liquid fuel ensures the prevention of pre-ignition.
Several experimental engines were built at the Bletchley factory. One of these was installed at the offices of "The Fenny Stratford Times", another to the local waterworks and a third to the brush factory of Messrs Cooks. The quality of engineering on these engines was rather poor, and so a batch of four were ordered and built by George Wailes & Co., Euston Road, London.
There are no known survivors of these early Akroyd engines.
In 1891, Akroyd-Stuart realised that the engine was ready for quantity production and he needed to find a company with the facilities to do this. Richard Hornsby & Son, at Grantham were offered the manufacturing rights. They took the advice of their Chief Engineer , Mr 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 Sow, in Doncaster, in June 1891.
The first production Hornsby-Akroyd, No 101, was installed, together with No 102, at the Great Brickhill Waterworks, at Fenny Stratford; leaving the Grantham factory in May 1892. They worked regularly until 1923, when No 101 was purchased by Mr Evans, a Bletchley timber merchant. In 1939 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 has now believed to have been shipped to Germany following the take-over of the Ruston business by MAN group.
The Hornsby-Akroyd was an instant success, and a total of 32417 engines of the type were built. Its uses were numerous, and it was produced in both horizontal and vertical form, stationary and portable. It was used to power the first oil tractor in 1896 and the first oil locomotive, also in 1896.
A 20hp Hornsby-Akroyd engined tractor was the World's first cataerpillar tractor, in 1905. Ray Hooley has a unique movie film of early Hornsby chain (caterpillar) tractors, filmed in 1908, including views of the Hornsby-Akroyd engined machine.
The Hornsby-Akroyd passed through three main phases:- pre 1905, 1905-1912 and 1912 onward. Separate instruction books and parts lists were published for each type. Ray Hooley possesses copies of all publications issued. Ray also holds the records of all engines sold by Hornsbys.