LNWR 2-2-2 3020 Cornwall
Encyclopedia
London & North Western Railway 2-2-2
No. 3020 Cornwall is a preserved steam locomotive
. She was built at Crewe
in 1847. She was originally a 4-2-2
in 1847, but was extensively rebuilt, and converted to a 2-2-2 in 1858.
Later on, increasing engine power would require better adhesion than could be achieved with single driving wheels, but that was not yet a problem at this time.
Along with needing large wheels for speed, stability required a low centre of gravity, and thus a low-slung boiler. The difficulty is that both of these needs are in conflict, requiring the driving axle position to overlap the boiler position.
One solution to this was the Crampton
design, where the driving axle was moved behind the boiler's firebox
. These engines were relatively long in comparison to their contemporaries and had long rigid frames, sometimes with as many as three carrying axles ahead of the driving axle, for a 6-2-0
wheel arrangement. Cramptons were most popular in France and Germany, but some were also used in England, by companies including the London & North Western Railway (LNWR).
One of these LNWR Cramptons, "Liverpool" was notably long, with an eight-wheeler (6-2-0) layout and rigid wheelbase of 18' 6". Although fast and capable of working heavy trains for long distances, it damaged the roadbed owing to the long rigid frame.
Francis Trevithick
had a notable pedigree as a locomotive engineer, being the son of Richard
. He had moved North to become resident engineer, then Locomotive Superintendent of the Grand Junction Railway
(GJR) (later formed into the LNWR). "Cornwall" was named after the county of his birth.
"Cornwall" was an attempt to avoid the damaging long wheelbase of the Cramptons, whilst still permitting large driving wheels. By moving the driving axle ahead of the firebox, one of the carrying axles could be moved backwards, giving a shorter overall wheelbase. The difficulty of how to fit the axles past the boiler recurred, to which Trevithick provided an "extremely complicated" solution. The boiler was placed entirely underneath the driving axle. Even then, it was necessary to recess a transverse channel across the top of the boiler, so as to provide clearance for the driving axle. The trailing carrying axle passed through a crosswise tube through the middle of the firebox. This made assembly difficult, but as it was only a straight carrying axle rather than a cranked driving axle, the tube diameter required was manageable. This use of a cross-firebox axle tube was part of Crampton's patent of 1842. As completed in 1847, and first numbered 173, 'Cornwall' was a 4-2-2
with 8' 6" drivers, paired leading wheels of 3' 6", single trailing wheels of 4' and an overall wheelbase of 16' 6". This is the condition in which she was exhibited at The Great Exhibition
of 1851.
The Railway Gazette , cited in , suggests that there was an even earlier design for 'Cornwall', as a 2-2-2
with single 4' wheels both forward and back. It's uncertain if 'Cornwall' was ever built in this form. The drawing does show a considerable front overhang, with a high load placed on the front axle. If constructed like this, the likelihood is that it would suffer the same problems as its contemporary, Gooch
's first 2-2-2 'Great Western' class of 1846, where a broken front axle led to re-design as a 4-2-2.
A typical Crampton feature, previously used on 'Liverpool', was the large diameter of the outside eccentrics used to drive the valve gear. These were so large as to be larger than the driving cranks, thus avoiding the need for an overhung (and potentially weak) crank. The 17½" × 24" cylinders were horizontal, fed by inclined steam chests above them.
In 1858, Ramsbottom
redesigned Cornwall almost completely. Little survived unchanged, other than the outside frames and the centres of the drivers. The boiler was now moved entirely above the driving axle, without any notches, channels or tubes, to what would now be regarded as conventional practice.
New cylinders and valve gear were provided, fractionally smaller at 17¼" × 24". Wheel arrangement was now 2-2-2, shortening the wheelbase still further to 14' 10". Ramsbottom also included his newly designed tamper-proof safety valve
.
Another minor rebuild in the 1870s provided a typically LNWR style of cab, with a short roof and semi-open sides. She was given her current number, 3020, in June 1886.
On final retirement, 'Cornwall' was deliberately preserved, one of the first locomotives to be so treated.
and resides at Locomotion
.
2-2-2
Under the Whyte notation for the classification of steam locomotives, 2-2-2 represents the wheel arrangement of two leading wheels on one axle two powered driving wheels on one axle, and two trailing wheels on one axle. The wheel arrangement both provided more stability and enabled a larger firebox...
No. 3020 Cornwall is a preserved steam locomotive
Steam locomotive
A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...
. She was built at Crewe
Crewe Works
Crewe railway works is a British railway engineering facility built in 1840 by the Grand Junction Railway. It is located in the town of Crewe, in the county of Cheshire....
in 1847. She was originally a 4-2-2
4-2-2
Under the Whyte notation for the classification of steam locomotives, 4-2-2 represents the wheel arrangement of four leading wheels on two axles, two powered driving wheels on one axle, and two trailing wheels on one axle....
in 1847, but was extensively rebuilt, and converted to a 2-2-2 in 1858.
Early high-speed locomotive design
In the 1840s, express passenger locomotive design was focussed on the need for single large-diameter driving wheels of around 8 foot (96"). The wheel diameter is effectively the "gearbox ratio" of a steam engine. Large driving wheels deliver the high linear tyre speed needed for fast locomotives, whilst keeping the axle bearing and piston speeds low enough to remain within the technology limits of the day.Later on, increasing engine power would require better adhesion than could be achieved with single driving wheels, but that was not yet a problem at this time.
Along with needing large wheels for speed, stability required a low centre of gravity, and thus a low-slung boiler. The difficulty is that both of these needs are in conflict, requiring the driving axle position to overlap the boiler position.
One solution to this was the Crampton
Crampton locomotive
A Crampton locomotive is a type of steam locomotive designed by Thomas Russell Crampton and built by various firms from 1846. The main British builders were Tulk and Ley and Robert Stephenson and Company....
design, where the driving axle was moved behind the boiler's firebox
Firebox
In a steam engine, the firebox is the area where the fuel is burned, producing heat to boil the water in the boiler. Most are somewhat box-shaped, hence the name.-Railway locomotive firebox :...
. These engines were relatively long in comparison to their contemporaries and had long rigid frames, sometimes with as many as three carrying axles ahead of the driving axle, for a 6-2-0
6-2-0
In the Whyte notation, a 6-2-0 is a railroad steam locomotive that has an unpowered three-axle leading truck followed by a single powered driving axle...
wheel arrangement. Cramptons were most popular in France and Germany, but some were also used in England, by companies including the London & North Western Railway (LNWR).
One of these LNWR Cramptons, "Liverpool" was notably long, with an eight-wheeler (6-2-0) layout and rigid wheelbase of 18' 6". Although fast and capable of working heavy trains for long distances, it damaged the roadbed owing to the long rigid frame.
1847 design by Trevithick
Francis Trevithick
Francis Trevithick , from Camborne, Cornwall, was one of the first locomotive engineers of the London and North Western Railway .- Life :...
had a notable pedigree as a locomotive engineer, being the son of Richard
Richard Trevithick
Richard Trevithick was a British inventor and mining engineer from Cornwall. His most significant success was the high pressure steam engine and he also built the first full-scale working railway steam locomotive...
. He had moved North to become resident engineer, then Locomotive Superintendent of the Grand Junction Railway
Grand Junction Railway
The Grand Junction Railway was an early railway company in the United Kingdom, which existed between 1833 and 1846 when it was merged into the London and North Western Railway...
(GJR) (later formed into the LNWR). "Cornwall" was named after the county of his birth.
"Cornwall" was an attempt to avoid the damaging long wheelbase of the Cramptons, whilst still permitting large driving wheels. By moving the driving axle ahead of the firebox, one of the carrying axles could be moved backwards, giving a shorter overall wheelbase. The difficulty of how to fit the axles past the boiler recurred, to which Trevithick provided an "extremely complicated" solution. The boiler was placed entirely underneath the driving axle. Even then, it was necessary to recess a transverse channel across the top of the boiler, so as to provide clearance for the driving axle. The trailing carrying axle passed through a crosswise tube through the middle of the firebox. This made assembly difficult, but as it was only a straight carrying axle rather than a cranked driving axle, the tube diameter required was manageable. This use of a cross-firebox axle tube was part of Crampton's patent of 1842. As completed in 1847, and first numbered 173, 'Cornwall' was a 4-2-2
4-2-2
Under the Whyte notation for the classification of steam locomotives, 4-2-2 represents the wheel arrangement of four leading wheels on two axles, two powered driving wheels on one axle, and two trailing wheels on one axle....
with 8' 6" drivers, paired leading wheels of 3' 6", single trailing wheels of 4' and an overall wheelbase of 16' 6". This is the condition in which she was exhibited at The Great Exhibition
The Great Exhibition
The Great Exhibition of the Works of Industry of all Nations or The Great Exhibition, sometimes referred to as the Crystal Palace Exhibition in reference to the temporary structure in which it was held, was an international exhibition that took place in Hyde Park, London, from 1 May to 15 October...
of 1851.
The Railway Gazette , cited in , suggests that there was an even earlier design for 'Cornwall', as a 2-2-2
2-2-2
Under the Whyte notation for the classification of steam locomotives, 2-2-2 represents the wheel arrangement of two leading wheels on one axle two powered driving wheels on one axle, and two trailing wheels on one axle. The wheel arrangement both provided more stability and enabled a larger firebox...
with single 4' wheels both forward and back. It's uncertain if 'Cornwall' was ever built in this form. The drawing does show a considerable front overhang, with a high load placed on the front axle. If constructed like this, the likelihood is that it would suffer the same problems as its contemporary, Gooch
Daniel Gooch
Sir Daniel Gooch, 1st Baronet was an English railway and transatlantic cable engineer and Conservative politician who sat in the House of Commons from 1865 to 1885...
's first 2-2-2 'Great Western' class of 1846, where a broken front axle led to re-design as a 4-2-2.
A typical Crampton feature, previously used on 'Liverpool', was the large diameter of the outside eccentrics used to drive the valve gear. These were so large as to be larger than the driving cranks, thus avoiding the need for an overhung (and potentially weak) crank. The 17½" × 24" cylinders were horizontal, fed by inclined steam chests above them.
1858 rebuilding by Ramsbottom
John Ramsbottom (engineer)
John Ramsbottom was an English mechanical engineer who created many inventions for railways, including the piston ring, the Ramsbottom safety valve, the displacement lubricator, and the water trough.- Biography :...
redesigned Cornwall almost completely. Little survived unchanged, other than the outside frames and the centres of the drivers. The boiler was now moved entirely above the driving axle, without any notches, channels or tubes, to what would now be regarded as conventional practice.
New cylinders and valve gear were provided, fractionally smaller at 17¼" × 24". Wheel arrangement was now 2-2-2, shortening the wheelbase still further to 14' 10". Ramsbottom also included his newly designed tamper-proof safety valve
Safety valve
A safety valve is a valve mechanism for the automatic release of a substance from a boiler, pressure vessel, or other system when the pressure or temperature exceeds preset limits....
.
Another minor rebuild in the 1870s provided a typically LNWR style of cab, with a short roof and semi-open sides. She was given her current number, 3020, in June 1886.
In service
'Cornwall' was a famously successful high-speed passenger express engine of its period. Charles Rous-Marten (cited in ) reported an 1884 run from Crewe to Chester behind 'Cornwall' (now far from new, and of antiquated design) at an average speed of 50.7 mph, reaching 70 mph down Whitmore bank. It remained in express service on the Liverpool-Manchester route until withdrawn in 1902. In 1925, Ahrons reports that it was still in service hauling the Mechanical Engineer's inspection coach.On final retirement, 'Cornwall' was deliberately preserved, one of the first locomotives to be so treated.
Preservation today
She is owned by the National Railway MuseumNational Railway Museum
The National Railway Museum is a museum in York forming part of the British National Museum of Science and Industry and telling the story of rail transport in Britain and its impact on society. It has won many awards, including the European Museum of the Year Award in 2001...
and resides at Locomotion
Shildon Locomotion Museum
Shildon Locomotion Museum is a railway museum in Shildon, County Durham, England. The museum is a branch of the National Railway Museum , which is part of the National Museum of Science and Industry...
.
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