Jenny Lind locomotive
|Builder||E. B. Wilson and Company|
|UIC classification||1A1 n2|
|Gauge||4 ft 8 1⁄2 in (1,435 mm)|
|4 ft 0 in (1.219 m)|
|Driver diameter||6 ft 0 in (1.829 m)|
|4 ft 0 in (1.219 m)|
|Boiler pressure||120 lbf/in² (827 kPa)|
|800 sq ft (74 m2)|
|Cylinder size||15 × 20 in (381 × 508 mm)|
|Tractive effort||6,375 lbf (28.36 kN)|
|Railroad(s)||London and Brighton Railway|
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. The general design proved to be very successful that the manufacturers adopted it for use on other railways, and it became the first mass-produced locomotive type. The 'Jenny Lind' type was also widely copied during the late 1840s and 1850s, and into the 1860s.
David Joy, the Chief Draughtsman of E. B. Wilson and Company, 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. 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 like 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 wrought iron coupling rods to break especially at speed. Thus four and six-coupled locomotives were used for freight trains.
Joy and Fenton settled on a medium sized boiler, 800 sq ft (74 m2) heated surface area, with a pressure of 120 lbf/in² (827 kPa) and concentrated on its steaming abilities. In this, James Fenton had particular expertise. The engine had 15-by-20-inch (380 × 510 mm) inside cylinders and 6-foot-0-inch-diameter (1.83 m) 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 4-foot-0-inch-diameter (1.22 m) 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 minimized the overhang at each end.
After 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.
Jenny Lind type
The new class proved to be so successful that the design was used by Wilson's as their standard design and more than seventy examples 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'.
Other manufacturers and railways also adopted the type. John Chester Craven, Kirtley's successor at Brighton, built a class of five similar 'Jenny Lind singles' in 1853-4. An enlarged type was also built by Beyer, Peacock and Company in 1860 to the Portuguese South Western Railway.
- Hamilton Ellis, C. (1971). The London Brighton and South Coast Railway. Ian Allan. ISBN 0-7110-0269-X. p.38-9.
- * 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
- Lowe.J.W. (1975) British Steam Locomotive Builders. London: Guild Publishing
- Bradley, D.L. (1971). Locomotives of the London Brighton and South Coast Railway. Part 1. Railway Correspondence and Travel Society. p.52.
- Hamilton Ellis, The pictorial history of railways, Hamlyn, 1968, p.58.