Southern Railway N Class
Encyclopedia
The SECR N class was a type of 2-6-0
("mogul") steam locomotive
designed in 1914 by Richard Maunsell
for mixed-traffic
duties on the South Eastern and Chatham Railway
(SECR). Built between 1917 and 1934, it was the first non-Great Western Railway
(GWR) type to use and improve upon the basic design principles established by GWR Chief Mechanical Engineer
(CME) George Jackson Churchward. The N class was based on the GWR 4300 class
design, improved with Midland Railway
concepts.
The N class was mechanically similar to the SECR K class 2-6-4
passenger tank engine, also by Maunsell. It influenced future 2-6-0 development in Britain and provided the basis for the 3-cylinder N1 class
of 1922. Production was delayed by the outbreak of the First World War in 1914, and the first N class rolled out of Ashford Works
in 1917, three years after design work was completed. The class replaced obsolete 0-6-0
s as part of the SECR's fleet standardisation, as they used parts interchangeable with those of other classes.
Eighty N class locomotives were built in three batches between the First and Second World Wars. Fifty were assembled from kits of parts made at the Royal Arsenal
, Woolwich
, giving rise to the nickname of "Woolworths". They operated over most of the Southern Railway (SR) network, and were used by the Southern Region
of British Railways (BR) until the last was withdrawn in 1966. One N class locomotive is preserved on the Watercress Line
in Hampshire, pending overhaul.
(SECR): increased freight and passenger train loadings, poor track quality, and weak, lightly built bridges. An increasing number of passengers used the SECR to reach the cross-Channel ferries at Dover
and Folkestone
between 1910 and 1913, and heavy goods trains between Tonbridge
and Hither Green
marshalling yard stretched the capabilities of existing locomotives and infrastructure. On the lines of the former London, Chatham and Dover Railway
(LCDR), flint beach pebbles on a bed of ash had been used for ballast
. Conventional track ballast has irregular shapes that "lock" together to keep the track in place, whereas the smooth pebbles used by the LCDR failed to prevent track movement under strain. The economies in construction meant that only locomotives with low axle loadings could operate safely on the track. These restrictions meant that the SECR was unable to follow a coherent locomotive strategy that reduced costs and increased serviceability. The railway's Operating Department had to use mismatched classes of underpowered and obsolete 4-4-0
and 0-6-0
locomotives because they could operate within the restrictions imposed by the infrastructure. This meant frequent double-heading
that added to operational costs.
Richard Maunsell was appointed CME of the SECR in 1913, following the retirement of Harry Wainwright
due to ill health. Wainwright left a legacy of competent but unspectacular locomotives that struggled to cope with the increased train lengths and loadings. Maunsell took control of the short-term situation by improving existing designs, and he introduced new engines to progressively replace obsolete classes. New designs could also cut costs on the SECR, as one capable mixed-traffic locomotive could undertake the work of two separate passenger or freight types. The first new design was to become Maunsell's N class 2-6-0.
The N class was designed by Maunsell in 1914 to provide a sturdy mixed-traffic locomotive with high route availability
. Intended to replace several obsolete 0-6-0
types, the N class was the first step in the SECR's fleet standardisation programme, which also included the K class 2-6-4T passenger tank locomotive
. Maunsell enlisted the help of former GWR engineer Harold Holcroft
, who suggested that a 2-6-0 wheel arrangement
would allow the class to operate on the poor-quality track in north Kent
. This arrangement allowed for a longer wheelbase with leading axle to permit greater stability at speed on tight track curves, which had constrained the size of locomotives operating on the SECR. A longer locomotive could also accommodate a larger boiler
than an 0-6-0, giving the N class sufficient power to avoid double-heading of locomotives on heavier trains.
The N class incorporated the principles of power and reliability established by George Churchward
, using a Belpaire firebox
that sloped downwards towards the cab instead of a round-topped version, a regulator located in the smokebox
, long-travel valves for free running up to 70 mph (31.3 m/s), a sharply tapered and domeless
boiler, and a right-hand driving position. These features are attributed to Holcroft, who worked on the GWR 4300 class
before joining the SECR. The boiler was intended to become a standard component for use on future SECR locomotive designs, thereby reducing construction times and improving organisation at the works. The size was constrained by the heavier axle-loading of Maunsell’s proposed 2-6-4
tank locomotive
variant of the N class, the K class, and was consequently smaller than was otherwise possible on the 2-6-0 chassis. The need to reduce overall weight also meant that the latter would feature lightly braced frames
.
Maunsell's Chief Locomotive Draughtsman, James Clayton, brought functional Midland Railway
influences to the design, such as the shape of the cab and the drumhead-type
smokebox, which sat on a saddle that was of wider diameter than the fully lagged and clad boiler. Clayton was also responsible for the tender and chimney designs. Snifting valve
s were provided to prevent vacuum formation in the cylinders when the locomotive was stationary, and the outside Walschaerts valve gear incorporated single slide-bars and piston tail rods. Innovations added by Maunsell's team included steam-powered locomotive brakes, locating the boiler water top feed inside a dome-like cover with external clackboxes
and water feed pipes mounted on either side, and a new type of superheater
that segregated saturated and superheated steam. Maunsell also incorporated a screw reverser to control valve events, which was easier to maintain than the complex steam reverser configuration of previous SECR designs. All components were standardised for interchange with similar locomotive classes to ease maintenance and reduce production costs.
Production of the first batch was delayed by the outbreak of the First World War. Assembly began towards the end of the war and the first locomotive, No. 810, emerged from Ashford Works for proving trials in July 1917, one month after the first K class tank, whose design was derived from the N class. Entering service in August 1917, No. 810 was trialled for three years before another 15 locomotives (Nos. 811–825) were ordered in 1919. These were built between 1920 and 1923; their construction delayed by a backlog of repair work caused by the war. The first left Ashford Works in June 1920, featuring a greater superheating surface area within the boiler as a result of operational experience with No. 810. All locomotives were equipped with 3500 gallons (15,911.3 l) tenders.
In 1922 modifications were made to No. 822 during assembly. This was because production delays at Ashford prevented the construction of a proposed 3-cylinder design drawn-up in 1919. Maunsell and Holcroft revised No. 822's cylinder arrangement to accommodate a third inside cylinder fitted between the frames. The outside cylinders were also reduced to 16 by 26 in (406.4 by 660.4 mm) diameter to accommodate the inside cylinder and its associated valve
linkages. The differences between No. 822 and the rest of the N class meant that this locomotive was re-designated as the 1919 proposal, becoming the prototype of the SR N1 class
when completed in March 1923.
drew up a contract for a second batch to the same specification – to be constructed at the Royal Arsenal
, Woolwich
. The government backing came as part of a proposal to nationalise the railways, which would require a standard fleet of locomotives to promote economies in production and maintenance. The nationalisation proposal was abandoned; instead, the government passed the 1921 Railways Act
, which grouped the railways into the "Big Four
" in 1923. Construction of the second batch went ahead to retain skilled labour at Woolwich, but the fabrication of 119 boilers for allocation to the kits of parts was contracted-out because of limited production capacity at Woolwich and Ashford; the North British Locomotive Company
built 85, Robert Stephenson and Company
20, and Kitson & Co.
14. By 1924, the prefabricated components stored at Woolwich formed 100 complete N class kits for purchase from the government.
The newly created Southern Railway
, which had absorbed the SECR in the 1923 "Grouping", undertook trials in the spring of 1924 to compare the performance of its freight locomotives. Because the Ns were designed to haul both freight and passenger traffic, Maunsell, as the newly-appointed Chief Mechanical Engineer
of the Southern Railway, decided to compare the design with the N1, LSWR S15 and LB&SCR K
classes in trials that involved hauling trains of 65 loaded wagons. Although the S15 was superior in freight haulage capacity and operational economy, the N class’ good all-round performance on passenger and freight meant that the type was adopted as the company's standard mixed-traffic design. The Southern Railway subsequently purchased fifty "Woolwich" kits for assembly at Ashford between June 1924 and August 1925. These were identical to the SECR batch and were given numbers in the series A826–A875. The Midland Great Western Railway
of Ireland bought 12 kits prior to absorption by the Great Southern and Western Railway
, which bought an extra 15. The latter 15 locomotives were divided into eight GSR Class 372 with 5 in 6 in (1.68 m) driving wheels and six GSR Class 393 with 6 in 0 in (1.83 m) driving wheels: the final kit was kept for spares.
The Metropolitan Railway
purchased six kits for conversion to the Metropolitan Railway K Class
2-6-4T tank engines, which were similar in outline to the SECR K class. The remaining 17 complete kits at Woolwich were purchased by the Southern Railway, and formed the basis of later locomotive classes such as the three-cylinder SR W class 2-6-4
tank locomotive. The prototype W class was produced in 1932 from N class parts with the addition of water tanks, a coal bunker, a rear bogie
and a third cylinder between the frames
. Woolwich also stocked a surplus of N class bogie components, and these were bought by the Southern for rebuilding the LB&SCR E1 class
0-6-0
tanks into the E1R class 0-6-2
tanks.
was replaced with the lower-profile version used on the U1 class, which increased route availability by allowing the locomotives to pass under lower bridges and tunnels. Maunsell had began to research smoke deflection techniques to improve driver visibility on the King Arthur class
between 1926 and 1927, which resulted in the adoption of a standard smoke deflector design for the Southern Railway. A smaller version was fitted to Nos. 1400–1414 during construction.
Before entering service, the batch was attached to 4000 gallons (18,184.4 l) tenders to increase operational range over the Southern Railway's long Western section routes. Despite this advantage, tenders fitted to the eight left-hand drive examples were intended for use with right-hand drive locomotives. This resulted in the location of the fireman's fittings on the "wrong" side of the cab. The design also necessitated the addition of a step to the footplate
, as the boiler backhead
was lower than the fall-plate that connected the tender and cab floors. The new batch incorporated a new set of footsteps beneath the front buffer beam, modified slide-bars and the dome
was redesigned to incorporate the regulator to ease access during routine maintenance.
After "The Grouping" in 1923, the N class remained on the former SECR network, which was incorporated into the Southern Railway's Eastern section. Typical services included , Ashford and freights, and Cannon Street to Dover passenger trains. The spring of 1924 saw Nos. A815 and A825 transferred to the former LSWR mainline between Waterloo and Guildford
for trials. These proved successful, and paved the way for the allocation of most of the Woolwich batch to the Southern Railway's Western section. The type regularly replaced Dugald Drummond
's ageing LSWR T9 class 4-4-0s on portions of the Atlantic Coast Express
over the steeply graded mainlines west of Exeter
.
The N class was also successful on the Central section, where they worked along-side Lawson Billinton's
LB&SCR K class
2-6-0s. However the large cylinder and cab sizes of the N class prevented use of the type on the Eastern section's Tonbridge–Hastings line
. The route's narrow bridges and tunnels were unable to accommodate the class, and provided justification for using the narrower 3-cylinder N1 class 2-6-0 on the route. Despite these restrictions, the class was capable of hauling heavy loads at moderate speeds, a useful attribute that was exploited throughout the Second World War. The entire class came into British Railways' ownership in 1948 and could be seen in most areas of the Southern Region
.
The quality of the original design was such that No. A866 was put on display at the British Empire Exhibition
at Wembley
from May to November 1925, and no class-wide modifications were made until 1934. This was when the SECR and Woolwich batches began to receive new domes and front footsteps during overhauls and general repairs. These were the same design as those used on Nos. 1400–1414, and were intended to standardise components between the batches. The SECR and Woolwich batches also received smoke deflectors
to prevent drifting smoke from obscuring the driver's vision ahead. The U1 chimneys replaced the standard N class type on the earlier locomotives, which, along with the removal of the piston tail rods on the earlier batches, created a truly standardised appearance.
In 1937, Maunsell's replacement Oliver Bulleid
saw no need to improve draughting of the class, and spared them from trials with Lemaître
multiple-jet blastpipe
s and wide-diameter chimneys. However, he had Maunsell's smokebox-mounted anti-vacuum snifting valve
s removed at the end of the Second World War in an effort to reduce maintenance. Bulleid also had eight new 4000 gallons (18,184.4 l) tenders constructed specially for the left-hand drive locomotives. In 1947, No. 1831 was given electric lighting and converted to oil-burning as part of government-backed fuel trials in anticipation of a post-war coal shortage, though it was reverted to coal-firing in December 1948.
The class was heavily used by British Railways: 29 locomotives required replacement cylinders between 1955 and 1961 due to excessive wear. Frames
were occasionally replaced due to stress caused by heavy use, and the steam circuit was revised when new cylinders were fitted: the inside steam pipes of Maunsell's original design were replaced by outside steam pipes emerging from the smokebox
, behind the smoke deflectors
. From 1957, some of the locomotives had larger-diameter BR Standard Class 4
chimneys fitted to improve draughting with poor-quality coal, though the decline of steam on the Southern Region precluded use on the entire class. Crew reports maintained that the latter modifications cut fuel and water consumption. The final set of modifications constituted the fitting of new injectors and Automatic Warning System
(AWS) equipment in 1957 and 1959 respectively.
to No. A819 in 1924. The trial was moderately successful, and the pump remained in use until removal in 1927. In June 1930, No. A816 was withdrawn from service for the application of experimental Anderson steam conservation equipment at Eastleigh Works. This was designed by a Scottish marine draughtsman, Mr. A. P. H. Anderson, who proposed the use of a fan system to condense spent steam and improve draughting of the fire on long-distance runs in regions with poor access to water.
No. A816 emerged from Eastleigh in August 1931 for trials, but was stopped when temperature variations within the condensing equipment caused water leakage. Modifications were made to improve the draughting of the locomotive, incorporating a box-like chimney attached to the condenser array by pipes. No. A816 was released for more trials, and produced performances well-below those displayed by the unmodified members of the class. The experiment was ended when the system's developers ran out of money, and the locomotive was subsequently rebuilt to original configuration. No. A816 re-entered service as No. 1816 in August 1936.
The final experiment with performance enhancement began in October 1933, when No. 1850 had its Walschaerts valve gear replaced with J. T. Marshall valve gear
at Eastleigh Works. The engine was trialled on the Western section, where the gear showed promise at slower speeds, with reduced consumption of coal and water. Problems were encountered at speeds over 50 mph (22.4 m/s), at which a severe "knocking" sound was reported by the footplate crew. When trialled on a Basingstoke–Waterloo semi-fast (a high-speed passenger train that stops at selected intermediate stations), the valve gear disintegrated near . After immediate withdrawal from traffic, the locomotive had its Walschaerts valve gear re-fitted and No. 1850 re-entered traffic in April 1934.
in 1959. The reduction of work precipitated a phased reduction of the class that began with the withdrawal of No. 31409 in November 1962. The withdrawal programme intensified after boundary changes on the Southern Region placed the lines west of Salisbury under Western Region
control in 1963. Class members based at Exmouth Junction
shed were withdrawn in 1964, whilst the Southern Region's allocation was gradually replaced by Bulleid's Light Pacifics. The last operational members of the class were Nos. 31405 and 31408; both were withdrawn in June 1966.
on the LSWR
) with black and white lining, primrose yellow numbering and "Southern" on the tender. This livery was first applied to No. 825.
From 1925, the class was repainted in a darker olive green livery, introduced by Maunsell, with plain white lining, black borders and primrose yellow markings. In 1939, shortly after the start of the Second World War, locomotives Nos. 1413 and 1850 were painted in unlined olive green because of labour shortages. In 1941, Nos. 1821, 1825, 1847, 1878 and 1403 were operated in unlined olive green with Bulleid's gilt block lettering. Labour and paint shortages during the Second World War meant that all N class locomotives were painted in plain black by 1945. In 1946, two locomotives, Nos. 1817 and 1854, were repainted in Bulleid's malachite green livery, with yellow and black lining and "Sunshine" yellow lettering.
The 15 locomotives constructed by Ashford Works for the SECR between August 1917 and December 1923 were numbered 810–824. The Royal Arsenal batch of 50 locomotives purchased by the newly formed Southern Railway from 1923 were numbered A825–A875; the numbers followed consecutively from the Ashford batch but with a prefix "A" to denote a locomotive allocated for overhaul at Ashford Works. The prefix was gradually applied to the SECR batch. From 1928, a new system was adopted where all Southern Railway locomotives were renumbered into one sequence. The SECR and Woolwich N class batches became Nos. 1810–1875. The final batch of 15 locomotives, built between 1932 and 1934, were numbered 1400–1414 from new.
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The N class was the first to combine Churchward design principles with the best practices of other railways; it was an important step in the development of the British 2-6-0, providing inspiration for the LMS Hughes Crab
of 1926 and subsequent Maunsell designs. The locomotives were well-received by crews, who nicknamed them "Woolworths", because the majority were fabricated from cheaply produced parts from Woolwich. The robustness and reliability of the design ensured that their sphere of operation was expanded to cover most of the Southern Railway network. The utility of the N class as capable mixed-traffic locomotives ensured their continued use until withdrawal in 1966.
One member of the class is preserved, No. 31874, which was rescued in March 1974 from the Woodham Brothers scrapyard in Barry, Vale of Glamorgan, South Wales
. One of the "Woolwich" batch, this locomotive was purchased and restored for use on the Mid-Hants Railway
; it was steamed for the first time in preservation in 1977, and was operational at the railway's re-opening as a heritage attraction in April 1977. The locomotive was withdrawn in 1998 due to problems that require firebox reconstruction, and as of 2009 is stored pending overhaul.
2-6-0
Under the Whyte notation for the classification of steam locomotives, 2-6-0 represents the wheel arrangement of two leading wheels on one axle, usually in a leading truck, six powered and coupled driving wheels on three axles, and no trailing wheels. This arrangement is commonly called a Mogul...
("mogul") 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...
designed in 1914 by Richard Maunsell
Richard Maunsell
Richard Edward Lloyd Maunsell held the post of Chief Mechanical Engineer of the South Eastern and Chatham Railway from 1913 until the 1923 Grouping and then the post of CME of the Southern Railway in England until 1937....
for mixed-traffic
Mixed-traffic locomotive
A mixed-traffic locomotive is one designed to be capable of hauling both passenger trains and freight trains. The term is mostly used in the United Kingdom and those nations following British practice...
duties on the South Eastern and Chatham Railway
South Eastern and Chatham Railway
The South Eastern and Chatham Railway Companies Joint Management Committee , known by its shorter name of the South Eastern and Chatham Railway was a working union of two neighbouring rival railways, the South Eastern Railway and London, Chatham and Dover Railway , that operated services between...
(SECR). Built between 1917 and 1934, it was the first non-Great Western Railway
Great Western Railway
The Great Western Railway was a British railway company that linked London with the south-west and west of England and most of Wales. It was founded in 1833, received its enabling Act of Parliament in 1835 and ran its first trains in 1838...
(GWR) type to use and improve upon the basic design principles established by GWR Chief Mechanical Engineer
Chief Mechanical Engineer
Chief Mechanical Engineer and Locomotive Superintendent are titles applied by British, Australian, and New Zealand railway companies to the person ultimately responsible to the board of the company for the building and maintaining of the locomotives and rolling stock...
(CME) George Jackson Churchward. The N class was based on the GWR 4300 class
GWR 4300 Class
The Great Western Railway 4300 Class is a class of 2-6-0 steam locomotive.- Overview :The class was introduced in 1911 to a G.J. Churchward design. 342 were built until 1932...
design, improved with Midland Railway
Midland Railway
The Midland Railway was a railway company in the United Kingdom from 1844 to 1922, when it became part of the London, Midland and Scottish Railway....
concepts.
The N class was mechanically similar to the SECR K class 2-6-4
2-6-4
Under the Whyte notation for the classification of steam locomotives, a 2-6-4 locomotive has two leading wheels, six coupled driving wheels and four trailing wheels...
passenger tank engine, also by Maunsell. It influenced future 2-6-0 development in Britain and provided the basis for the 3-cylinder N1 class
SR N1 Class
The SECR N1 class was a type of 3-cylinder 2-6-0 steam locomotive designed by Richard Maunsell for mixed traffic duties, initially on the South Eastern and Chatham Railway , and later operated for the Southern Railway...
of 1922. Production was delayed by the outbreak of the First World War in 1914, and the first N class rolled out of Ashford Works
Ashford railway works
Ashford railway works was in the town of Ashford in the county of Kent in England.-South Eastern Railway:Ashford locomotive works was built by the South Eastern Railway on a new site in 1847, replacing an earlier locomotive repair facility at New Cross in London...
in 1917, three years after design work was completed. The class replaced obsolete 0-6-0
0-6-0
Under the Whyte notation for the classification of steam locomotives, 0-6-0 represents the wheel arrangement of no leading wheels, six powered and coupled driving wheels on three axles, and no trailing wheels...
s as part of the SECR's fleet standardisation, as they used parts interchangeable with those of other classes.
Eighty N class locomotives were built in three batches between the First and Second World Wars. Fifty were assembled from kits of parts made at the Royal Arsenal
Royal Arsenal
The Royal Arsenal, Woolwich, originally known as the Woolwich Warren, carried out armaments manufacture, ammunition proofing and explosives research for the British armed forces. It was sited on the south bank of the River Thames in Woolwich in south-east London, England.-Early history:The Warren...
, Woolwich
Woolwich
Woolwich is a district in south London, England, located in the London Borough of Greenwich. The area is identified in the London Plan as one of 35 major centres in Greater London.Woolwich formed part of Kent until 1889 when the County of London was created...
, giving rise to the nickname of "Woolworths". They operated over most of the Southern Railway (SR) network, and were used by the Southern Region
Southern Region of British Railways
The Southern Region was a region of British Railways from 1948. The region ceased to be an operating unit in its own right in the 1980s and was wound up at the end of 1992. The region covered south London, southern England and the south coast, including the busy commuter belt areas of Kent, Sussex...
of British Railways (BR) until the last was withdrawn in 1966. One N class locomotive is preserved on the Watercress Line
Watercress Line
The Watercress Line is the marketing name of the Mid-Hants Railway, a heritage railway in Hampshire, England, running from New Alresford to Alton where it connects to the National Rail network. The line gained its popular name in the days that it was used to transport locally grown watercress to...
in Hampshire, pending overhaul.
Background
Three factors dictated the type of locomotive that could operate on the South Eastern and Chatham RailwaySouth Eastern and Chatham Railway
The South Eastern and Chatham Railway Companies Joint Management Committee , known by its shorter name of the South Eastern and Chatham Railway was a working union of two neighbouring rival railways, the South Eastern Railway and London, Chatham and Dover Railway , that operated services between...
(SECR): increased freight and passenger train loadings, poor track quality, and weak, lightly built bridges. An increasing number of passengers used the SECR to reach the cross-Channel ferries at Dover
Dover
Dover is a town and major ferry port in the home county of Kent, in South East England. It faces France across the narrowest part of the English Channel, and lies south-east of Canterbury; east of Kent's administrative capital Maidstone; and north-east along the coastline from Dungeness and Hastings...
and Folkestone
Folkestone
Folkestone is the principal town in the Shepway District of Kent, England. Its original site was in a valley in the sea cliffs and it developed through fishing and its closeness to the Continent as a landing place and trading port. The coming of the railways, the building of a ferry port, and its...
between 1910 and 1913, and heavy goods trains between Tonbridge
Tonbridge
Tonbridge is a market town in the English county of Kent, with a population of 30,340 in 2007. It is located on the River Medway, approximately 4 miles north of Tunbridge Wells, 12 miles south west of Maidstone and 29 miles south east of London...
and Hither Green
Hither Green
Hither Green is a district in south east London, England, located in the London Borough of Lewisham. It is situated 6.6 miles south east of Charing Cross, and on the Prime Meridian....
marshalling yard stretched the capabilities of existing locomotives and infrastructure. On the lines of the former London, Chatham and Dover Railway
London, Chatham and Dover Railway
The London, Chatham and Dover Railway was a railway company in south-eastern England from 1859 until the 1923 grouping which united it with other companies to form the Southern Railway. Its lines ran through London and northern and eastern Kent to form a significant part of the Greater London...
(LCDR), flint beach pebbles on a bed of ash had been used for ballast
Track ballast
Track ballast forms the trackbed upon which railway sleepers or railroad ties are laid. It is packed between, below, and around the ties. It is used to facilitate drainage of water, to distribute the load from the railroad ties, and also to keep down vegetation that might interfere with the track...
. Conventional track ballast has irregular shapes that "lock" together to keep the track in place, whereas the smooth pebbles used by the LCDR failed to prevent track movement under strain. The economies in construction meant that only locomotives with low axle loadings could operate safely on the track. These restrictions meant that the SECR was unable to follow a coherent locomotive strategy that reduced costs and increased serviceability. The railway's Operating Department had to use mismatched classes of underpowered and obsolete 4-4-0
4-4-0
Under the Whyte notation for the classification of steam locomotives, 4-4-0 represents the wheel arrangement of four leading wheels on two axles , four powered and coupled driving wheels on two axles, and no trailing wheels...
and 0-6-0
0-6-0
Under the Whyte notation for the classification of steam locomotives, 0-6-0 represents the wheel arrangement of no leading wheels, six powered and coupled driving wheels on three axles, and no trailing wheels...
locomotives because they could operate within the restrictions imposed by the infrastructure. This meant frequent double-heading
Double-heading
In railroad terminology, double-heading or double heading indicates the use of two locomotives at the front of a train, each operated individually by its own crew. The practice of triple-heading involves the use of three locomotives....
that added to operational costs.
Richard Maunsell was appointed CME of the SECR in 1913, following the retirement of Harry Wainwright
Harry Wainwright
Harry Smith Wainwright was the Locomotive, Carriage and Wagon Superintendent of the South Eastern and Chatham Railway from 1899 to 1913. He is best known for a series of simple but competent locomotives produced under his direction at the company's Ashford railway works in the early years of the...
due to ill health. Wainwright left a legacy of competent but unspectacular locomotives that struggled to cope with the increased train lengths and loadings. Maunsell took control of the short-term situation by improving existing designs, and he introduced new engines to progressively replace obsolete classes. New designs could also cut costs on the SECR, as one capable mixed-traffic locomotive could undertake the work of two separate passenger or freight types. The first new design was to become Maunsell's N class 2-6-0.
Design and construction
- For detailed information on numbering variations, see: Livery and numbering
The N class was designed by Maunsell in 1914 to provide a sturdy mixed-traffic locomotive with high route availability
Route availability
Route Availability is the system by which the permanent way and supporting works of the National Rail network of Great Britain are graded. All routes are allocated an RA number between 1 and 10....
. Intended to replace several obsolete 0-6-0
0-6-0
Under the Whyte notation for the classification of steam locomotives, 0-6-0 represents the wheel arrangement of no leading wheels, six powered and coupled driving wheels on three axles, and no trailing wheels...
types, the N class was the first step in the SECR's fleet standardisation programme, which also included the K class 2-6-4T passenger tank locomotive
Tank locomotive
A tank locomotive or tank engine is a steam locomotive that carries its water in one or more on-board water tanks, instead of pulling it behind it in a tender. It will most likely also have some kind of bunker to hold the fuel. There are several different types of tank locomotive dependent upon...
. Maunsell enlisted the help of former GWR engineer Harold Holcroft
Harold Holcroft
Harold Holcroft was a British railway and mechanical engineer who worked for the Great Western Railway , the South Eastern and Chatham Railway and the Southern Railway...
, who suggested that a 2-6-0 wheel arrangement
Whyte notation
The Whyte notation for classifying steam locomotives by wheel arrangement was devised by Frederick Methvan Whyte and came into use in the early twentieth century encouraged by an editorial in American Engineer and Railroad Journal...
would allow the class to operate on the poor-quality track in north Kent
Kent
Kent is a county in southeast England, and is one of the home counties. It borders East Sussex, Surrey and Greater London and has a defined boundary with Essex in the middle of the Thames Estuary. The ceremonial county boundaries of Kent include the shire county of Kent and the unitary borough of...
. This arrangement allowed for a longer wheelbase with leading axle to permit greater stability at speed on tight track curves, which had constrained the size of locomotives operating on the SECR. A longer locomotive could also accommodate a larger boiler
Fire-tube boiler
A fire-tube boiler is a type of boiler in which hot gases from a fire pass through one or more tubes running through a sealed container of water...
than an 0-6-0, giving the N class sufficient power to avoid double-heading of locomotives on heavier trains.
The N class incorporated the principles of power and reliability established by George Churchward
George Jackson Churchward
George Jackson Churchward CBE was Chief Mechanical Engineer of the Great Western Railway in the United Kingdom from 1902 to 1922.-Early career:...
, using a Belpaire firebox
Belpaire firebox
The Belpaire firebox is a type of firebox used on steam locomotives. It was invented by Alfred Belpaire of Belgium. It has a greater surface area at the top of the firebox, improving heat transfer and steam production...
that sloped downwards towards the cab instead of a round-topped version, a regulator located in the smokebox
Smokebox
A smokebox is one of the major basic parts of a Steam locomotive exhaust system. Smoke and hot gases pass from the firebox through tubes where they pass heat to the surrounding water in the boiler. The smoke then enters the smokebox, and is exhausted to the atmosphere through the chimney .To assist...
, long-travel valves for free running up to 70 mph (31.3 m/s), a sharply tapered and domeless
Steam dome
A Steam dome is a vessel fitted to the top of the boiler of a steam locomotive. It contains the opening to the main steam pipe and its purpose is to allow this opening to be kept well above the water level in the boiler...
boiler, and a right-hand driving position. These features are attributed to Holcroft, who worked on the GWR 4300 class
GWR 4300 Class
The Great Western Railway 4300 Class is a class of 2-6-0 steam locomotive.- Overview :The class was introduced in 1911 to a G.J. Churchward design. 342 were built until 1932...
before joining the SECR. The boiler was intended to become a standard component for use on future SECR locomotive designs, thereby reducing construction times and improving organisation at the works. The size was constrained by the heavier axle-loading of Maunsell’s proposed 2-6-4
2-6-4
Under the Whyte notation for the classification of steam locomotives, a 2-6-4 locomotive has two leading wheels, six coupled driving wheels and four trailing wheels...
tank locomotive
Tank locomotive
A tank locomotive or tank engine is a steam locomotive that carries its water in one or more on-board water tanks, instead of pulling it behind it in a tender. It will most likely also have some kind of bunker to hold the fuel. There are several different types of tank locomotive dependent upon...
variant of the N class, the K class, and was consequently smaller than was otherwise possible on the 2-6-0 chassis. The need to reduce overall weight also meant that the latter would feature lightly braced frames
Locomotive frame
A locomotive frame is the structure that forms the backbone of the railway locomotive, giving it strength and supporting the superstructure elements such as a cab, boiler or bodywork. The vast majority of locomotives have had a frame structure of some kind...
.
Maunsell's Chief Locomotive Draughtsman, James Clayton, brought functional Midland Railway
Midland Railway
The Midland Railway was a railway company in the United Kingdom from 1844 to 1922, when it became part of the London, Midland and Scottish Railway....
influences to the design, such as the shape of the cab and the drumhead-type
Drumhead
A drumhead is a membrane stretched over one or both of the open ends of a drum. The drumhead is struck with sticks, mallets, or hands so that it vibrates and the sound resonates through the drum.-History:...
smokebox, which sat on a saddle that was of wider diameter than the fully lagged and clad boiler. Clayton was also responsible for the tender and chimney designs. Snifting valve
Snifting valve
A snifting valve is an automatic anti-vacuum valve used in a steam locomotive when coasting. The word Snift imitates the sound made by the valve....
s were provided to prevent vacuum formation in the cylinders when the locomotive was stationary, and the outside Walschaerts valve gear incorporated single slide-bars and piston tail rods. Innovations added by Maunsell's team included steam-powered locomotive brakes, locating the boiler water top feed inside a dome-like cover with external clackboxes
Check valve
A check valve, clack valve, non-return valve or one-way valve is a mechanical device, a valve, which normally allows fluid to flow through it in only one direction....
and water feed pipes mounted on either side, and a new type of superheater
Superheater
A superheater is a device used to convert saturated steam or wet steam into dry steam used for power generation or processes. There are three types of superheaters namely: radiant, convection, and separately fired...
that segregated saturated and superheated steam. Maunsell also incorporated a screw reverser to control valve events, which was easier to maintain than the complex steam reverser configuration of previous SECR designs. All components were standardised for interchange with similar locomotive classes to ease maintenance and reduce production costs.
SECR batch
- For a detailed examination of the modifications made to No. 822, see: SR N1 classSR N1 ClassThe SECR N1 class was a type of 3-cylinder 2-6-0 steam locomotive designed by Richard Maunsell for mixed traffic duties, initially on the South Eastern and Chatham Railway , and later operated for the Southern Railway...
.
Production of the first batch was delayed by the outbreak of the First World War. Assembly began towards the end of the war and the first locomotive, No. 810, emerged from Ashford Works for proving trials in July 1917, one month after the first K class tank, whose design was derived from the N class. Entering service in August 1917, No. 810 was trialled for three years before another 15 locomotives (Nos. 811–825) were ordered in 1919. These were built between 1920 and 1923; their construction delayed by a backlog of repair work caused by the war. The first left Ashford Works in June 1920, featuring a greater superheating surface area within the boiler as a result of operational experience with No. 810. All locomotives were equipped with 3500 gallons (15,911.3 l) tenders.
In 1922 modifications were made to No. 822 during assembly. This was because production delays at Ashford prevented the construction of a proposed 3-cylinder design drawn-up in 1919. Maunsell and Holcroft revised No. 822's cylinder arrangement to accommodate a third inside cylinder fitted between the frames. The outside cylinders were also reduced to 16 by 26 in (406.4 by 660.4 mm) diameter to accommodate the inside cylinder and its associated valve
Valve gear
The valve gear of a steam engine is the mechanism that operates the inlet and exhaust valves to admit steam into the cylinder and allow exhaust steam to escape, respectively, at the correct points in the cycle...
linkages. The differences between No. 822 and the rest of the N class meant that this locomotive was re-designated as the 1919 proposal, becoming the prototype of the SR N1 class
SR N1 Class
The SECR N1 class was a type of 3-cylinder 2-6-0 steam locomotive designed by Richard Maunsell for mixed traffic duties, initially on the South Eastern and Chatham Railway , and later operated for the Southern Railway...
when completed in March 1923.
"Woolwich" batch
The first batch of the N class proved successful in service, and few problems were encountered after settling-in. The Ministry of SupplyMinistry of Supply
The Ministry of Supply was a department of the UK Government formed in 1939 to co-ordinate the supply of equipment to all three British armed forces, headed by the Minister of Supply. There was, however, a separate ministry responsible for aircraft production and the Admiralty retained...
drew up a contract for a second batch to the same specification – to be constructed at the Royal Arsenal
Royal Arsenal
The Royal Arsenal, Woolwich, originally known as the Woolwich Warren, carried out armaments manufacture, ammunition proofing and explosives research for the British armed forces. It was sited on the south bank of the River Thames in Woolwich in south-east London, England.-Early history:The Warren...
, Woolwich
Woolwich
Woolwich is a district in south London, England, located in the London Borough of Greenwich. The area is identified in the London Plan as one of 35 major centres in Greater London.Woolwich formed part of Kent until 1889 when the County of London was created...
. The government backing came as part of a proposal to nationalise the railways, which would require a standard fleet of locomotives to promote economies in production and maintenance. The nationalisation proposal was abandoned; instead, the government passed the 1921 Railways Act
Railways Act 1921
The Railways Act 1921, also known as the Grouping Act, was an enactment by the British government of David Lloyd George intended to stem the losses being made by many of the country's 120 railway companies, move the railways away from internal competition, and to retain some of the benefits which...
, which grouped the railways into the "Big Four
Big Four British railway companies
The Big Four was a name used to describe the four largest railway companies in the United Kingdom in the period 1923-1947. The name was coined by the Railway Magazine in its issue of February 1923: "The Big Four of the New Railway Era".The Big Four were:...
" in 1923. Construction of the second batch went ahead to retain skilled labour at Woolwich, but the fabrication of 119 boilers for allocation to the kits of parts was contracted-out because of limited production capacity at Woolwich and Ashford; the North British Locomotive Company
North British Locomotive Company
The North British Locomotive Company was created in 1903 through the merger of three Glasgow locomotive manufacturing companies; Sharp Stewart and Company , Neilson, Reid and Company and Dübs and Company , creating the largest locomotive manufacturing company in Europe.Its main factories were...
built 85, Robert Stephenson and Company
Robert Stephenson and Company
Robert Stephenson and Company was a locomotive manufacturing company founded in 1823. It was the first company set up specifically to build railway engines.- Foundation and early success :...
20, and Kitson & Co.
Kitson & Co.
Kitson and Company was a locomotive manufacturer based in Hunslet, Leeds, West Yorkshire, England.-Early history:The company started as James Kitson at the Airedale Foundry, off Pearson Street, Hunslet in 1835 with Charles Todd as a partner...
14. By 1924, the prefabricated components stored at Woolwich formed 100 complete N class kits for purchase from the government.
The newly created Southern Railway
Southern Railway (Great Britain)
The Southern Railway was a British railway company established in the 1923 Grouping. It linked London with the Channel ports, South West England, South coast resorts and Kent...
, which had absorbed the SECR in the 1923 "Grouping", undertook trials in the spring of 1924 to compare the performance of its freight locomotives. Because the Ns were designed to haul both freight and passenger traffic, Maunsell, as the newly-appointed Chief Mechanical Engineer
Chief Mechanical Engineer
Chief Mechanical Engineer and Locomotive Superintendent are titles applied by British, Australian, and New Zealand railway companies to the person ultimately responsible to the board of the company for the building and maintaining of the locomotives and rolling stock...
of the Southern Railway, decided to compare the design with the N1, LSWR S15 and LB&SCR K
LB&SCR K class
London Brighton and South Coast Railway Class K were powerful 2-6-0 mixed traffic locomotives designed by L. B. Billinton for the London Brighton and South Coast Railway in 1913. They appeared shortly before the First World War and the first ten examples of the class did prodigious work during...
classes in trials that involved hauling trains of 65 loaded wagons. Although the S15 was superior in freight haulage capacity and operational economy, the N class’ good all-round performance on passenger and freight meant that the type was adopted as the company's standard mixed-traffic design. The Southern Railway subsequently purchased fifty "Woolwich" kits for assembly at Ashford between June 1924 and August 1925. These were identical to the SECR batch and were given numbers in the series A826–A875. The Midland Great Western Railway
Midland Great Western Railway
The Midland Great Western Railway was the third largest Irish gauge railway company in Ireland. It was incorporated in 1845 and absorbed into the Great Southern Railway in 1924. It served part of Leinster, County Cavan in Ulster and much of Connaught...
of Ireland bought 12 kits prior to absorption by the Great Southern and Western Railway
Great Southern and Western Railway
The Great Southern and Western Railway was the largest Irish gauge railway company in Ireland in the late 19th and early 20th centuries...
, which bought an extra 15. The latter 15 locomotives were divided into eight GSR Class 372 with 5 in 6 in (1.68 m) driving wheels and six GSR Class 393 with 6 in 0 in (1.83 m) driving wheels: the final kit was kept for spares.
The Metropolitan Railway
Metropolitan railway
Metropolitan Railway can refer to:* Metropolitan line, part of the London Underground* Metropolitan Railway, the first underground railway to be built in London...
purchased six kits for conversion to the Metropolitan Railway K Class
Metropolitan Railway K Class
The Metropolitan Railway K class consisted of six 2-6-4T steam locomotives, numbered 111 to 116. They were built by Armstrong Whitworth in 1925 using parts manufactured at the Royal Arsenal, Woolwich, to the design of the South Eastern and Chatham Railway N Class 2-6-0 locomotives...
2-6-4T tank engines, which were similar in outline to the SECR K class. The remaining 17 complete kits at Woolwich were purchased by the Southern Railway, and formed the basis of later locomotive classes such as the three-cylinder SR W class 2-6-4
2-6-4
Under the Whyte notation for the classification of steam locomotives, a 2-6-4 locomotive has two leading wheels, six coupled driving wheels and four trailing wheels...
tank locomotive. The prototype W class was produced in 1932 from N class parts with the addition of water tanks, a coal bunker, a rear bogie
Bogie
A bogie is a wheeled wagon or trolley. In mechanics terms, a bogie is a chassis or framework carrying wheels, attached to a vehicle. It can be fixed in place, as on a cargo truck, mounted on a swivel, as on a railway carriage/car or locomotive, or sprung as in the suspension of a caterpillar...
and a third cylinder between the frames
Locomotive frame
A locomotive frame is the structure that forms the backbone of the railway locomotive, giving it strength and supporting the superstructure elements such as a cab, boiler or bodywork. The vast majority of locomotives have had a frame structure of some kind...
. Woolwich also stocked a surplus of N class bogie components, and these were bought by the Southern for rebuilding the LB&SCR E1 class
LB&SCR E1 class
The London, Brighton and South Coast Railway E1 Class were 0-6-0T steam locomotives designed by William Stroudley in 1874 for short-distance goods and piloting duties. They were originally classified E, and generally known as "E-tanks"; They were reclassified E1 in the time of D. E...
0-6-0
0-6-0
Under the Whyte notation for the classification of steam locomotives, 0-6-0 represents the wheel arrangement of no leading wheels, six powered and coupled driving wheels on three axles, and no trailing wheels...
tanks into the E1R class 0-6-2
0-6-2
Under the Whyte notation for the classification of steam locomotives, 0-6-2 represents the wheel arrangement of no leading wheels, six powered and coupled driving wheels on three axles, and two trailing wheels on one axle...
tanks.
Southern Railway batch
In 1932, the Southern Railway ordered a final batch of 15 locomotives (Nos. 1400–1414) to expand class availability on the Southern Railway's network. These were constructed at Ashford works and differed from the previous 65 in a number of ways. The cabs of the final eight locomotives (Nos. 1407–1414) were fitted for left-hand driving, which was adopted as standard by the Southern Railway. The original N class chimneyChimney
A chimney is a structure for venting hot flue gases or smoke from a boiler, stove, furnace or fireplace to the outside atmosphere. Chimneys are typically vertical, or as near as possible to vertical, to ensure that the gases flow smoothly, drawing air into the combustion in what is known as the...
was replaced with the lower-profile version used on the U1 class, which increased route availability by allowing the locomotives to pass under lower bridges and tunnels. Maunsell had began to research smoke deflection techniques to improve driver visibility on the King Arthur class
LSWR N15 Class
The LSWR N15 class was a British 2–cylinder 4-6-0 express passenger steam locomotive designed by Robert W. Urie. The class has a complex build history spanning three sub-classes and eight years of construction from 1919 to 1926...
between 1926 and 1927, which resulted in the adoption of a standard smoke deflector design for the Southern Railway. A smaller version was fitted to Nos. 1400–1414 during construction.
Before entering service, the batch was attached to 4000 gallons (18,184.4 l) tenders to increase operational range over the Southern Railway's long Western section routes. Despite this advantage, tenders fitted to the eight left-hand drive examples were intended for use with right-hand drive locomotives. This resulted in the location of the fireman's fittings on the "wrong" side of the cab. The design also necessitated the addition of a step to the footplate
Footplate
The footplate of a steam locomotive is a large metal plate that rests on top of the frames and is normally covered with wooden floorboards. It is usually the full width of the locomotive and extends from the front of the cab to the rear of cab or coal bunker just above the buffer beam. The...
, as the boiler backhead
Backhead
In rail terminology, backhead refers to the wall of a steam locomotive's firebox in the cab of the locomotive. The locomotive's controls are mounted on the backhead....
was lower than the fall-plate that connected the tender and cab floors. The new batch incorporated a new set of footsteps beneath the front buffer beam, modified slide-bars and the dome
Steam dome
A Steam dome is a vessel fitted to the top of the boiler of a steam locomotive. It contains the opening to the main steam pipe and its purpose is to allow this opening to be kept well above the water level in the boiler...
was redesigned to incorporate the regulator to ease access during routine maintenance.
N class construction history
| Year | Batch | Quantity | SECR/SR numbers | Notes |
|---|---|---|---|---|
| 1917, 1920–23 | |
|
810, 811–824 | Locomotive No. 822 modified during construction to 3-cylinder arrangement, became SECR N1 class prototype |
| 1924 | |
|
|
Purchased by Southern Railway Southern Railway (Great Britain) The Southern Railway was a British railway company established in the 1923 Grouping. It linked London with the Channel ports, South West England, South coast resorts and Kent... |
| 1924 | (outside purchaser) |
|
33 sold, 17 spare for future projects | |
| 1932–34 | Southern Railway (Great Britain) The Southern Railway was a British railway company established in the 1923 Grouping. It linked London with the Channel ports, South West England, South coast resorts and Kent... |
|
|
|
Operational details
The N class was used to haul services over most of the SECR network and became a familiar sight on the difficult cross-country route between and , on which the steep gradients had taxed the company's 4-4-0 and 0-6-0 designs. The success of the 2-6-0 in traversing this route was due to their higher-capacity tapered boilers that produced an ample supply of steam, and the small 5 ft 6 in (1.68 m) driving wheels that delivered considerable tractive effort when climbing gradients such as the 1 in 100 between and .After "The Grouping" in 1923, the N class remained on the former SECR network, which was incorporated into the Southern Railway's Eastern section. Typical services included , Ashford and freights, and Cannon Street to Dover passenger trains. The spring of 1924 saw Nos. A815 and A825 transferred to the former LSWR mainline between Waterloo and Guildford
Guildford (Surrey) railway station
Guildford railway station is an important railway junction on the Portsmouth Direct Line serving the town of Guildford in Surrey, England. It is 30.3 miles from London Waterloo....
for trials. These proved successful, and paved the way for the allocation of most of the Woolwich batch to the Southern Railway's Western section. The type regularly replaced Dugald Drummond
Dugald Drummond
Dugald Drummond was a Scottish steam locomotive engineer. He had a career with the North British Railway, LB&SCR, Caledonian Railway and London and South Western Railway...
's ageing LSWR T9 class 4-4-0s on portions of the Atlantic Coast Express
Atlantic Coast Express
The Atlantic Coast Express was an express passenger train in England between Waterloo station, London and seaside resorts in the south-west...
over the steeply graded mainlines west of Exeter
Exeter
Exeter is a historic city in Devon, England. It lies within the ceremonial county of Devon, of which it is the county town as well as the home of Devon County Council. Currently the administrative area has the status of a non-metropolitan district, and is therefore under the administration of the...
.
The N class was also successful on the Central section, where they worked along-side Lawson Billinton's
L. B. Billinton
Lawson Boskovsky Billinton was the locomotive engineer of the London, Brighton and South Coast Railway from 1912 for ten years until his retirement in 1922....
LB&SCR K class
LB&SCR K class
London Brighton and South Coast Railway Class K were powerful 2-6-0 mixed traffic locomotives designed by L. B. Billinton for the London Brighton and South Coast Railway in 1913. They appeared shortly before the First World War and the first ten examples of the class did prodigious work during...
2-6-0s. However the large cylinder and cab sizes of the N class prevented use of the type on the Eastern section's Tonbridge–Hastings line
Hastings Line
The Hastings Line is a railway line in Kent and East Sussex linking Hastings with the main town of Tunbridge Wells, and from there into London via Sevenoaks.-Openings:The line was opened by the South Eastern Railway in main three stages: – :...
. The route's narrow bridges and tunnels were unable to accommodate the class, and provided justification for using the narrower 3-cylinder N1 class 2-6-0 on the route. Despite these restrictions, the class was capable of hauling heavy loads at moderate speeds, a useful attribute that was exploited throughout the Second World War. The entire class came into British Railways' ownership in 1948 and could be seen in most areas of the Southern Region
Southern Region of British Railways
The Southern Region was a region of British Railways from 1948. The region ceased to be an operating unit in its own right in the 1980s and was wound up at the end of 1992. The region covered south London, southern England and the south coast, including the busy commuter belt areas of Kent, Sussex...
.
Performance of the class and modifications
When introduced in 1917, the N class proved adept at hauling both passenger and freight services on the SECR. They were well liked by crews who appreciated the general robustness of the design, although the lightly constructed frames caused excessive vibration and rough riding on the footplate when worked hard. Despite there being little wrong with the original design, the N class’ full steaming potential was not realised because of the failure to capitalise upon a larger boiler, which was a direct consequence of Maunsell’s standardisation policy. Instead, the SECR batch was trial-fitted with "stovepipe" chimneys in an attempt to improve draughting. This was initially applied to No. 812 in 1921, although two more were fitted to Nos. 817 and 819 during construction because of a shortage of chimneys at Ashford Works. The chimney fitted to No. 819 was transferred to No. 818 sometime between 1921 and 1924, though all "stovepipes" had been replaced with the standard N class type by April 1927. Another trial saw the addition of a second slidebar to No. 825, which gave better support to the valve gear and helped protect it from spillage from the driving wheel sander fillers.The quality of the original design was such that No. A866 was put on display at the British Empire Exhibition
British Empire Exhibition
The British Empire Exhibition was a colonial exhibition held at Wembley, Middlesex in 1924 and 1925.-History:It was opened by King George V on St George's Day, 23 April 1924. The British Empire contained 58 countries at that time, and only Gambia and Gibraltar did not take part...
at Wembley
Wembley
Wembley is an area of northwest London, England, and part of the London Borough of Brent. It is home to the famous Wembley Stadium and Wembley Arena...
from May to November 1925, and no class-wide modifications were made until 1934. This was when the SECR and Woolwich batches began to receive new domes and front footsteps during overhauls and general repairs. These were the same design as those used on Nos. 1400–1414, and were intended to standardise components between the batches. The SECR and Woolwich batches also received smoke deflectors
Smoke deflectors
Smoke deflectors are vertical plates attached to the front of a steam locomotive on each side of the smokebox. They are designed to lift smoke away from the locomotive at speed so that the driver has better visibility unimpaired by drifting smoke....
to prevent drifting smoke from obscuring the driver's vision ahead. The U1 chimneys replaced the standard N class type on the earlier locomotives, which, along with the removal of the piston tail rods on the earlier batches, created a truly standardised appearance.
In 1937, Maunsell's replacement Oliver Bulleid
Oliver Bulleid
Oliver Vaughan Snell Bulleid was a British railway and mechanical engineer best known as the Chief Mechanical Engineer of the Southern Railway between 1937 and the 1948 nationalisation, developing many well-known locomotives.- Early life and Great Northern Railway :He was born in Invercargill,...
saw no need to improve draughting of the class, and spared them from trials with Lemaître
Jean Lemaître
Jean Lemaître was a mechanical engineer from the Nord Belge Railway, who developed a Steam locomotive exhaust system.The Lemaître Exhaust featured 5 nozzles in a circular pattern exhausting up a large-diameter stack, with a variable area nozzle exhausting up the center, and improved efficiency by...
multiple-jet blastpipe
Blastpipe
The blastpipe is part of the exhaust system of a steam locomotive that discharges exhaust steam from the cylinders into the smokebox beneath the chimney in order to increase the draught through the fire.- History :...
s and wide-diameter chimneys. However, he had Maunsell's smokebox-mounted anti-vacuum snifting valve
Snifting valve
A snifting valve is an automatic anti-vacuum valve used in a steam locomotive when coasting. The word Snift imitates the sound made by the valve....
s removed at the end of the Second World War in an effort to reduce maintenance. Bulleid also had eight new 4000 gallons (18,184.4 l) tenders constructed specially for the left-hand drive locomotives. In 1947, No. 1831 was given electric lighting and converted to oil-burning as part of government-backed fuel trials in anticipation of a post-war coal shortage, though it was reverted to coal-firing in December 1948.
The class was heavily used by British Railways: 29 locomotives required replacement cylinders between 1955 and 1961 due to excessive wear. Frames
Locomotive frame
A locomotive frame is the structure that forms the backbone of the railway locomotive, giving it strength and supporting the superstructure elements such as a cab, boiler or bodywork. The vast majority of locomotives have had a frame structure of some kind...
were occasionally replaced due to stress caused by heavy use, and the steam circuit was revised when new cylinders were fitted: the inside steam pipes of Maunsell's original design were replaced by outside steam pipes emerging from the smokebox
Smokebox
A smokebox is one of the major basic parts of a Steam locomotive exhaust system. Smoke and hot gases pass from the firebox through tubes where they pass heat to the surrounding water in the boiler. The smoke then enters the smokebox, and is exhausted to the atmosphere through the chimney .To assist...
, behind the smoke deflectors
Smoke deflectors
Smoke deflectors are vertical plates attached to the front of a steam locomotive on each side of the smokebox. They are designed to lift smoke away from the locomotive at speed so that the driver has better visibility unimpaired by drifting smoke....
. From 1957, some of the locomotives had larger-diameter BR Standard Class 4
BR standard class 4 4-6-0
The British Railways Standard Class 4 4-6-0 is a class of steam locomotives, 80 of which were built during the 1950s. Six have been preserved.-Background:...
chimneys fitted to improve draughting with poor-quality coal, though the decline of steam on the Southern Region precluded use on the entire class. Crew reports maintained that the latter modifications cut fuel and water consumption. The final set of modifications constituted the fitting of new injectors and Automatic Warning System
Automatic Warning System
The Automatic Warning System is a form of limited cab signalling and train protection system introduced in 1956 in the United Kingdom to help train drivers observe and obey signals. It was based on a 1930 system developed by Alfred Ernest Hudd and marketed as the "Strowger-Hudd" system...
(AWS) equipment in 1957 and 1959 respectively.
Experiments
Although sufficient for the Southern Railway's needs, the N class was an ideal test-bed for experiments with new steam technology. The first experiment entailed fitting a Worthington feed pumpHenry Rossiter Worthington
Henry Rossiter Worthington was an American mechanical engineer. He had several inventions leading to the perfection of the direct steam pump , patented the duplex steam pump , and built the first duplex waterworks engine, widely adopted and used for more than 75 years...
to No. A819 in 1924. The trial was moderately successful, and the pump remained in use until removal in 1927. In June 1930, No. A816 was withdrawn from service for the application of experimental Anderson steam conservation equipment at Eastleigh Works. This was designed by a Scottish marine draughtsman, Mr. A. P. H. Anderson, who proposed the use of a fan system to condense spent steam and improve draughting of the fire on long-distance runs in regions with poor access to water.
No. A816 emerged from Eastleigh in August 1931 for trials, but was stopped when temperature variations within the condensing equipment caused water leakage. Modifications were made to improve the draughting of the locomotive, incorporating a box-like chimney attached to the condenser array by pipes. No. A816 was released for more trials, and produced performances well-below those displayed by the unmodified members of the class. The experiment was ended when the system's developers ran out of money, and the locomotive was subsequently rebuilt to original configuration. No. A816 re-entered service as No. 1816 in August 1936.
The final experiment with performance enhancement began in October 1933, when No. 1850 had its Walschaerts valve gear replaced with J. T. Marshall valve gear
James Thompson Marshall
James Thompson Marshall was a British railway and mechanical engineer known for inventing the 'Marshall valve gear' for steam locomotive use.-Career and 'Marshall valve gear':...
at Eastleigh Works. The engine was trialled on the Western section, where the gear showed promise at slower speeds, with reduced consumption of coal and water. Problems were encountered at speeds over 50 mph (22.4 m/s), at which a severe "knocking" sound was reported by the footplate crew. When trialled on a Basingstoke–Waterloo semi-fast (a high-speed passenger train that stops at selected intermediate stations), the valve gear disintegrated near . After immediate withdrawal from traffic, the locomotive had its Walschaerts valve gear re-fitted and No. 1850 re-entered traffic in April 1934.
Withdrawal
Suitable work for the class began to decline after completion of the Kent Coast route electrificationRailway electrification system
A railway electrification system supplies electrical energy to railway locomotives and multiple units as well as trams so that they can operate without having an on-board prime mover. There are several different electrification systems in use throughout the world...
in 1959. The reduction of work precipitated a phased reduction of the class that began with the withdrawal of No. 31409 in November 1962. The withdrawal programme intensified after boundary changes on the Southern Region placed the lines west of Salisbury under Western Region
Western Region of British Railways
The Western Region was a region of British Railways from 1948. The region ceased to be an operating unit in its own right in the 1980s and was wound up at the end of 1992...
control in 1963. Class members based at Exmouth Junction
Exmouth Junction
Exmouth Junction is the railway junction where the Exmouth branch line diverges from the London Waterloo to Exeter main line in Exeter, Devon, England. It was for many years the location for one of the largest engine sheds in the former London and South Western Railway...
shed were withdrawn in 1964, whilst the Southern Region's allocation was gradually replaced by Bulleid's Light Pacifics. The last operational members of the class were Nos. 31405 and 31408; both were withdrawn in June 1966.
SECR and Southern Railway
N class locomotives were initially painted in an unlined dark grey livery with white lettering and numbering. This Maunsell grey livery was introduced by the SECR as a wartime economy measure. After Grouping in 1923, the Southern Railway replaced the different liveries of the constituent companies with a standard sage green livery (the colour was that previously used by Robert UrieRobert Urie
Robert Wallace Urie was a Scottish locomotive engineer who was the last chief mechanical engineer of the London and South Western Railway....
on the LSWR
London and South Western Railway
The London and South Western Railway was a railway company in England from 1838 to 1922. Its network extended from London to Plymouth via Salisbury and Exeter, with branches to Ilfracombe and Padstow and via Southampton to Bournemouth and Weymouth. It also had many routes connecting towns in...
) with black and white lining, primrose yellow numbering and "Southern" on the tender. This livery was first applied to No. 825.
From 1925, the class was repainted in a darker olive green livery, introduced by Maunsell, with plain white lining, black borders and primrose yellow markings. In 1939, shortly after the start of the Second World War, locomotives Nos. 1413 and 1850 were painted in unlined olive green because of labour shortages. In 1941, Nos. 1821, 1825, 1847, 1878 and 1403 were operated in unlined olive green with Bulleid's gilt block lettering. Labour and paint shortages during the Second World War meant that all N class locomotives were painted in plain black by 1945. In 1946, two locomotives, Nos. 1817 and 1854, were repainted in Bulleid's malachite green livery, with yellow and black lining and "Sunshine" yellow lettering.
The 15 locomotives constructed by Ashford Works for the SECR between August 1917 and December 1923 were numbered 810–824. The Royal Arsenal batch of 50 locomotives purchased by the newly formed Southern Railway from 1923 were numbered A825–A875; the numbers followed consecutively from the Ashford batch but with a prefix "A" to denote a locomotive allocated for overhaul at Ashford Works. The prefix was gradually applied to the SECR batch. From 1928, a new system was adopted where all Southern Railway locomotives were renumbered into one sequence. The SECR and Woolwich N class batches became Nos. 1810–1875. The final batch of 15 locomotives, built between 1932 and 1934, were numbered 1400–1414 from new.
British Railways
The class was absorbed by British Railways in 1948, and initially given the power classification 4MT in 1949. Under British Railways ownership, the class was reclassified from 4MT to 4P5FB in 1953; the "B" denoting the brake power rating when used on unfitted (non-vacuum braked) goods trains. The locomotives at first retained their Southern Railway livery, but with "British Railways" painted on the tender in Bulleid block lettering. Eight locomotives had light repairs prior to 1950 and were given an "S" prefix to the Southern number (e.g. s1405). From 1949 to 1950 N class locomotives were repainted in the British Railways mixed-traffic lined black livery with red, cream and grey lining and the British Railways crest on the tender. Numbering was changed to the British Railways standard numbering system: the series 31810–31875 was allocated to the earlier locomotives, and 31400–31414 to the final 15.Operational assessment and preservation
LMS Hughes Crab
The London Midland and Scottish Railway Hughes Crab or Horwich Mogul is a class of mixed traffic 2-6-0 steam locomotive built between 1926 and 1932. They are noted for their appearance with large highly-angled cylinders caused by restricted loading gauge...
of 1926 and subsequent Maunsell designs. The locomotives were well-received by crews, who nicknamed them "Woolworths", because the majority were fabricated from cheaply produced parts from Woolwich. The robustness and reliability of the design ensured that their sphere of operation was expanded to cover most of the Southern Railway network. The utility of the N class as capable mixed-traffic locomotives ensured their continued use until withdrawal in 1966.
One member of the class is preserved, No. 31874, which was rescued in March 1974 from the Woodham Brothers scrapyard in Barry, Vale of Glamorgan, South Wales
South Wales
South Wales is an area of Wales bordered by England and the Bristol Channel to the east and south, and Mid Wales and West Wales to the north and west. The most densely populated region in the south-west of the United Kingdom, it is home to around 2.1 million people and includes the capital city of...
. One of the "Woolwich" batch, this locomotive was purchased and restored for use on the Mid-Hants Railway
Watercress Line
The Watercress Line is the marketing name of the Mid-Hants Railway, a heritage railway in Hampshire, England, running from New Alresford to Alton where it connects to the National Rail network. The line gained its popular name in the days that it was used to transport locally grown watercress to...
; it was steamed for the first time in preservation in 1977, and was operational at the railway's re-opening as a heritage attraction in April 1977. The locomotive was withdrawn in 1998 due to problems that require firebox reconstruction, and as of 2009 is stored pending overhaul.