When the Liverpool and Manchester Railway was being built following authorisation by the Parliamentary Act of 1826, the decision regarding propulsion had not been made. The options were cable haulage, using a series of stationary steam engines along the line, or the use of self-propelled 'locomotive engines'. 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, and 'Rocket' was the winner. There's a brief description of this period in the post Early Locomotive Design.
The National Railway Museum 'Rocket' replica.
For the opening of the Liverpool and Manchester Railway, a number of locomotives fairly similar to 'Rocket' were built by the Robert Stephenson works.
Experience with the 'Rocket' class suggested a number of technical improvements which were incorporated in the very successful 'Planet' class. The Stephenson works produced four 'Planet' class locomotives by the end of 1830, with a further four in 1831, supplemented by two very similar locomotives manufactured by Fenton, Murray and Company. The design of the 'Planet' class was so successful that, for a number of years, locomotives were essentially derivatives or enlarged versions of 'Planet'.
The 'Planet' replica (with shortened chimney).
Liverpool & Manchester Railway company - Locomotive List, 1829-1834
Click here for larger view.
The above list, produced after a few years operation of the Liverpool and Manchester Railway, is worth studying in detail. It is taken from the book by Clement E. Stretton [reference 1]. The success of the railway is clear from the fact that no less than 36 locomotives appear on the list, headed by No. 1 'Rocket', built in 1929.
The 'Rocket' class
The cylinders on 'Rocket' were 8 inches in diameter, with a 16.5 inch stroke and the driving wheels were 4 feet 8.5 inches diameter. A further seven locomotives (No. 2 - No. 8) were built in 1830 to inaugurate the service. Although the list shows them as 'Rocket' class, there were a number of changes Compared with 'Rocket', the cylinder diameter was increased to 10 inches (on the first four locomotives) and again to 11 inches (on the final three locomotives). There was a small reduction in stroke to 16 inches and the driving wheel diameter was increased to 5 feet. The first four locomotives had a larger number of smaller diameter smoke tubes and a chimney similar to 'Rocket', swelled at the base to join onto the front of the boiler but, thereafter, the chimney was carried on a recognisable 'smokebox'. Note that the cylinders have been lowered from the steeply-inclined position of the original 'Rocket' to an almost-horizontal position to reduce impact on the track. 'Rocket' itself had the same cylinder position modification at some stage. On the last of the 'Rocket' class, No 8 'Northumbrian', illustrated in the Shaw print below, the mature form of the 'Stephensonian' boiler appears with a larger water-jacket firebox integrated with the boiler (which now has 132 smoke tubes of 1 and 5/8 inch diameter).
Shaw: Plate IV The Northumbrian Engine.
The 'Planet' class
The 'Planet' class quickly followed and the Robert Stephenson and Company works produced the first four class members in 1830 - 'Planet', 'Majestic', 'Mercury' and 'Mars' (No. 9 to No. 12). The 11 inch by 16 inch cylinders of the later 'Rocket' class engines were retained, as were the 5 foot diameter driving wheels but the configuration of the class was completely revised from an 0-2-2 to a 2-2-0, as described in the post The Planet Replica.
The diagram below shows the design of the cylinders for the 'Planet' class. Note that both front and rear covers were cast separately from the cylinder. Also note that the steam valve was split into two sections. This arrangement created extra wear and was not perpetuated.
Diagram of 'Planet' class cylinder (from Ahrons book [reference 2], drawing originally published in "The Engineer").
In 1831 the Stephenson works turned out another six 'Planet' engines - 'Jupiter', 'Saturn', 'Sun', 'Venus', 'Etna' and 'Victory'. In the same year Fenton, Murray and Company produced two 'Planet' class locomotives on the recommendation of Robert Stephenson & Co. (using Stephenson drawings), which were given the names 'Vulcan' and 'Fury'. Robert Stephenson & Co. also produced the first 4-coupled engines of the 'Samson' class, described below.
In 1832, another six 'Planet' locomotives were acquired by the Liverpool and Manchester Railway. Robert Stephenson & Co. produced 'Atlas', 'Vesta', Milo, Pluto and 'Ajax', whilst Fenton, Murray and Company built 'Leeds'. Of these six locomotives, only 'Vesta' and 'Leeds' had 11 inch by 16 inch cylinders - 'Atlas', 'Milo' and 'Pluto' had 12 inch by 16 inch cylinders and 'Ajax' was equipped wit 11 inch by 18 inch cylinders! In the same year 'Liver' was supplied by Bury and Galloway & Co. provided 'Caledonian' - something of a 'throwback' with vertical cylinders.
In 1833, Robert Stephenson & Co. supplied another 'Planet' class, 'Firefly', with the 11 inch by 18 inch cylinders which had first appeared on 'Ajax'. But more significant was the supply of a 2-2-2 locomotive - 'Patentee', the first of a new class, described below.
The 'Samson' class
A significant development in 1831 was the emergence of a 4-coupled version of 'Planet', intended for goods and banking duties. Cylinder size was enlarged to 12 x 16 inches. By having four equal-sized wheels and coupling them together, all the weight of the locomotive became adhesive. The crank pins on the trailing wheels were ball joints, to provide flexibility (like 'Rocket') whereas the crank pins on the leading wheels were parallel-sided. The drawing below shows the arrangement. Note that the elevation shows the front of the locomotive to the right, whereas on the plan, the front of the locomotive was on the left.
Elevation and Plan of 'Samson' class (from Ahrons book [reference 2], drawing originally published in "The Engineer").
The 'Patentee' class
Partly to improve riding and partly to facilitate the design of ever-larger locomotives, Robert Stephenson & Co. added a pair of carrying wheels at the rear of the locomotive. In a single-driver (like the 'Planet' class), this produced a 2-2-2, in a four-coupled design (like the 'Samson' class), this produced an 0-4-2. Cylinder size was enlarged to 12 x 18 inches. The design flexibility that this change offered meant that, for some years, locomotive design could be based on 'ringing the changes' on the 'Patentee' configuration.
Related posts in this blog
Early Locomotive Design.
The Planet Replica.
'Planet' at MOSI - The First 21 Years.
Book References
[1] 'The Development of the Locomotive - A Popular History 1803 - 1896' by Clement E. Stretton.
[2] 'The British Steam Railway Locomotive 1825 - 1925' by E. L. Ahrons, reprinted Bracken Books 1987 (ISBN 1 85170 103 6).
[3] 'A Century of Locomotive Building by Robert Stephenson & Co. 1823 - 1923' by J. G. H. Warren, reprinted David & Charles (7153 4378 5).
