Friday 12 January 2007

Early Locomotive Design

This post is based on a talk given by Jan Ford at the Museum of Science and Industry in Manchester.

In the eighteen twenties, Manchester was already a thriving city with a business class of prosperous, imaginative entrepreneurs. Landlocked, Manchester looked to Liverpool, both for the import of raw materials and for the export of finished products. But communications with Liverpool, by road and canal, were inconvenient and slow.

One of the most successful early railways was the Stockton and Darlington Railway opened in 1825 in the North East of England. Although it was a mineral line and speeds were slow, it proved that steam locomotives offered a practical method of shifting heavy loads on a regular basis. With this inspiration, the Manchester businessmen looked to build a railway line from Manchester to Liverpool. Passenger carrying was envisaged from the start. The promoters’ dream was to travel from Manchester to Liverpool, transact their business and return to Manchester in time for dinner the same day!

There were vested interests who opposed the railway and the first attempt at securing the necessary Act of Parliament failed. Better prepared for the second attempt, the Act was secured. George Stephenson became involved in the project and the route decided upon included gradients (‘inclined planes’) gentle enough to allow the use of steam locomotives on the main part of the route. But the matter was not cut-and-dried. Locomotive design was still in its infancy and the possibility of fixed steam engines with cable haulage was seriously entertained.

A stationary engine could, if required, be large and fed from a generously-proportioned boiler. Permanent arrangements for the supply of water and fuel could be made. In contrast, locomotive engines had to fit the boiler and all the mechanism of the steam engine together with supplies of coal and water on a wheeled carriage which then proceeded to shake itself to pieces whilst breaking the rails upon which it ran. Materials were of generally poor quality and production techniques, such as involved in the casting and boring of cylinders, were still primitive. Essentially, locomotive building was blacksmith’s work.

The Directors of the Liverpool and Manchester Railway decided upon a competition, with a £500 prize to the winner, to find the best steam locomotive design before finally deciding upon the method of traction for their line. In 1929, the Rainhill Trials were held, amid massive public interest. The watching spectators viewed the event like a horse race, but the Directors had a more serious intent, seeking a locomotive which could haul a significant load and prove reliable but was not so heavy as to damage the track. The competitors who made an appearance represented a variety of approaches to the problems.

‘Cycloped’ was an ingenious way of utilising the power of a horse on a railway but it represented a dead-end.

‘Novelty’ was the entrant which caught the eye of the crowd, dashing around at spectacular speeds. The design was derived from the reasonably-successful steam carriage but 'Novelty' was plagued with problems and the design would have been difficult to extend into a larger, more powerful machine.

'Perseverance' was another 'steam carriage' design but here the problems were so severe that she was withdrawn from the competition without running.

There were two contenders from the North East. The Stephensons, father and son, produced ‘Rocket’, the eventual winner. Timothy Hackworth competed with ‘Sans Pareil’. The similarities and differences between these locomotives illustrate the essentials of an effective locomotive design and we’ll study these competitors in greater detail in a later article.

Although ‘Rocket’ won the Rainhill Trials and the Stephensons produced a number of copies for the Liverpool and Manchester in the 1830s, they were rather lightweight machines. The fairly similar ‘Northumbrian’ class quickly followed. But, in very short order, the Stephensons produced the ‘Planet’ which, in its own way, was as revolutionary as ‘Rocket’ had been.

Having put the essentials in place, design evolved in a less spectacular manner. To allow a larger locomotive, an extra pair of wheels was added and the 2-2-2 wheel arrangement of the ‘Patentee’ was copied by a number of manufacturers. For goods engines requiring additional traction, the leading pair of wheels was replaced by a coupled axle, giving an 0-4-2 wheel arrangement. In 1838, when the short-lived partnership of Todd, Kitson and Laird built ‘Lion’ for the Liverpool and Manchester Railway, they produced an 0-4-2 of distinctly Stephenson appearance.

As materials improved, bar or plate frames tended to replace the use of sandwich frames (or simply hanging parts on the boiler itself) but the general layout of locomotives of this period, with horizontal boiler and more-or-less horizontal cylinders inside or outside the framing was retained for the next century.