Jenny Lind locomotive

From Wikipedia, the free encyclopedia

The Jenny Lind locomotive was the first of a class of ten steam locomotives built in 1847 for the London Brighton and South Coast Railway by E.B.Wilson and Company of Leeds, named after Jenny Lind who was a famous opera singer of the period.

David Joy, the Chief Draughtsman of E.B.Wilson, was asked to visit Brighton railway works to make tracings of the drawings of a 2-2-2 locomotive designed by John Gray for the railway so that ten further examples could be built. However, before he had completed the task, Gray had been dismissed from his post of Locomotive Superintendent, and his successor Thomas Kirtley did not favour Gray's complicated horse-leg motion. As a result it was left to Joy and James Fenton the works manager at E.B. Wilson to adapt the design.^[1] Joy had spent his formative years studying all the locomotives he came across, sketching them, making notes, and interrogating their owners and crews - and, if he could, getting rides on them.

As is usual in engineering, there were a number of trade-offs to be made in steam locomotive design. There is a limit to the rate that steam can be delivered to the pistons, therefore higher speed was obtained with larger driving wheels. These however limited the size of the boiler, since it needed to fit between them, particularly with the preoccupation of the time with a lower centre of gravity. The tendency had been to lengthen the boilers with supporting wheels front and rear. Thus passenger engines, such as the so-called Long Boiler locomotives were usually of a 4-2-0 wheel arrangement. However too long a boiler also created instability. Some locomotives improved adhesion for heavier loads by coupling pairs of driving wheels, however there was a tendency for the cast iron coupling rods to break especially at speed. Thus four-coupled locomotives were used for freight trains.

Joy and Fenton settled on a medium sized boiler, 800 sq ft (74 m²) capacity, and concentrated on its steaming abilities. In this, James Fenton had particular expertise. The engine had 15-inch (380 mm) by 20-inch (510 mm) inside cylinders and 6-foot (1.8 m) diameter driving wheels. Gray's so-called 'mixed' frame had an inside frame for the cylinders and driving wheels, with inside bearings, and an outside frame for the four foot diameter leading and trailing wheels, using outside bearings. The inside frame stopped at the firebox, so that the latter was as wide as the wheels would allow. By this means he minimised the overhang at each end.

After some strengthening of various members, the engine was three tons heavier than expected. However, it steamed freely and was economical on fuel. It was to this that its success was attributed, along with the increase in boiler pressure that had become possible over the years. However credit must be given to Joy's suspension arrangements that made it extremely smooth-running and stable.

The name 'Jenny Lind' was given to the first one delivered to the London Brighton and South Coast Railway, but the design was such a success that it became the name for the whole class of which seventy were built for various railways, including twenty-four for the Midland Railway. It could be said to be the first to be mass-produced to a consistent pattern. Indeed the manufacturers charged a hefty premium for variations, although in response to pressure, they later built a number of 'large jennies'.

John Chester Craven, Kirtley's successor at Brighton, later built a class of five similar 'Jenny Lind singles' in 1853-4.^[2]

[edit] References

• Sekon, G.A., (1908) Some Links in the Evolution of the Locomotive: the particulars extracted from the Diaries of the Late David Joy; Railway Magazine Volumes 22 & 23. Archived on "Steam Index" website

[edit] Picture Links

• "Science and Society" view of locomotive
• "Science and Society" pen drawing of side elevation