SECR K class
Encyclopedia
The SECR K class was a type of 2-6-4
tank locomotive
designed in 1914 by Richard Maunsell
for express passenger duties on the South Eastern and Chatham Railway
(SECR). The Southern Railway (SR) K1 class was a three-cylinder variant of the K class, designed in 1925 to suit a narrower loading gauge
. They were among the first non-Great Western Railway
(GWR) types to use and improve upon the basic design principles of power and standardisation established by GWR Chief Mechanical Engineer
(CME) George Jackson Churchward
. The locomotives were based on the GWR 4300 class
, improved by the Midland Railway
's ideals of simplicity and ease of maintenance.
The K class was designed to be mechanically similar to the SECR N class 2-6-0
mixed-traffic locomotives. The class was the earliest large-scale use of the 2-6-4 wheel arrangement in Britain. Production began towards the end of the First World War, and the prototype rolled out of Ashford Works
three years after design work was completed due to wartime production constraints. The class replaced obsolete 4-4-0
passenger locomotives in an SECR fleet standardisation programme.
Twenty-one locomotives were built: twenty K class (two cylinders) and one K1 class (three cylinders), the first in 1917 and the remainder between 1925 and 1926. They operated over the Eastern section of the Southern Railway network and were given the names of rivers, being referred as the River class from 1925. Crews referred to the K and K1 classes as "Rolling Rivers" because of their instability when travelling at speed. They were rebuilt as 2-cylinder SR U class and 3-cylinder SR U1 class 2-6-0s (respectively) following a railway accident at Sevenoaks, Kent
in 1927. They continued in service with British Railways (BR) until the last was withdrawn in 1966. One K class rebuild is preserved on the Watercress Line
in Hampshire and as of 2009 was being overhauled.
(SECR): the heavy passenger train loadings; the poor track quality; and the weak, lightly built bridges. On the lines of the former London, Chatham and Dover Railway
(LCDR) – inherited by the SECR in 1899 – beach pebbles had been used for ballast
instead of conventional ballast, which has irregular shapes that lock together to keep the track in place. These economies in construction meant that only locomotives with low axle loadings could operate safely over the track. The SECR was therefore unable to follow a coherent strategy to reduce the number of locomotive types inherited from the two constituent railways. Despite increased passenger and freight traffic between and the Kent
ish coast during the first decades of the 20th century, the Operating Department had to use mismatched classes of underpowered and obsolete 4-4-0
and 0-6-0
locomotives, which could operate within the restrictions imposed by the infrastructure. This resulted in frequent double-heading
, adding to operational costs.
Richard Maunsell was appointed CME of the SECR in 1913, following the enforced retirement of Harry Wainwright
, who had left a range of competent but unspectacular locomotive classes that struggled to cope with the increased train lengths and loadings. Maunsell reviewed the situation and planned to introduce six standard classes – using only two boiler designs – which would work the entire traffic of the railway. The first of these was the N class 2-6-0
, which gave the SECR a capable mixed-traffic locomotive
. For the express passenger design that could cope with the heavy boat train
s, Maunsell wanted to enlarge the existing L class
4-4-0
with Walschaerts valve gear and an enlarged superheater
, but this design would have resulted in a too heavy axle loading. Maunsell's newly recruited assistants, G.H. Pearson and Harold Holcroft
from the Great Western Railway
at Swindon and James Clayton from the Midland Railway
at Derby, had recently been involved in the design of large passenger tank engines and persuaded him to use the 2-6-4
wheel arrangement
, which would allow the class to operate at high speeds on the poor-quality track in north Kent.
locomotives in Britain, on the Great Central Railway
's 1B class
freight locomotives of 1914. However, the configuration was ideal for the SECR, because of its shorter mainlines, and allowed for a long wheelbase with a leading axle to permit greater stability at speed on track curves. The tightness of the curves on the former LCDR mainlines had constrained the size of locomotives operating on the SECR, as they had been hastily erected during the nineteenth century to compete with those of the South Eastern Railway
(SER). The longer locomotive could also accommodate a larger boiler
than a 4-4-0, giving sufficient power to avoid double-heading of locomotives on heavier trains.
The K class design used a "Bissel bogie
" leading axle and a plain trailing bogie
. The trailing bogie permitted the use of a large coal bunker that was capable of sustaining the locomotive over the run between London Charing Cross and , and side water tanks of 2000 imp gal (9,092.2 l) capacity were used, negating the need for a tender. The coupled wheelbase between the rear and centre driving wheels was reduced from that used on the mechanically identical N class to 7 in 9 in (2.36 m) to accommodate the bogie. The cab was fully enclosed, although the set of four small front spectacle plates (the windows on the front face of the cab for forward visibility) were the same as those used on the N class.
The K class was designed by Maunsell's team in 1914 as part of his proposed standardisation programme following the N class, but the designs were not shown to the railway directors until early 1915 to enable all six designs to be shown at once. The design 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 at high speeds, a sharply tapered and domeless
boiler, and a right-hand driving position. The inclusion of these features is attributed to Holcroft, Maunsell's personal assistant, who had worked on the GWR 4300 class
and the N class. James Clayton, Maunsell's Chief Locomotive Draughtsman, brought simpler and more 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. The latter was fitted with Ross pop safety valve
s and pressed to 200 psi (1.38 MPa).
Other innovations by Maunsell's team included greater superheating
surface area, locating the boiler water top feed inside a dome-like cover with external clackboxes
and water feed pipes mounted on either side, outside Walschaerts valve gear, and parts that could be shared with similar locomotive classes to reduce maintenance costs. The firebox was narrower towards the rear and featured a continuously sloping grate, whilst the ashpan was fitted with front and rear damper doors, the latter adjusted to clear the rear driving axle. The lower part of the coal bunker incorporated a water tank of 760 imp gal (3,455 l) capacity. This was connected to two 620 imp gal (2,818.6 l) side tanks
by two rectangular pipes on either side of the locomotive that also formed supports for the cab footplate
.
for wartime armaments manufacture. Assembly began in 1917 and the first, No. 790, emerged in July of that year. It was based at Bricklayers Arms depot, preceding the earlier N class design into service by one month. Further construction was deferred until after Ashford had caught up with the maintenance backlog caused by the war.
Ten more locomotives were ordered by the SECR from Ashford works in June 1920, and to speed delivery the construction of frames
, cylinders and side tanks was subcontracted to the Royal Arsenal
at Woolwich
. However, further severe delays at Ashford caused by the backlog of repair work meant that the boilers had to be supplied by the North British Locomotive Company
. Construction of these locomotives had not begun by 1 January 1923, when the Railways Act 1921
merged the SECR with other railways in southern England to form the Southern Railway
.
Maunsell was appointed CME of the newly formed Southern Railway in 1923, and inherited the 1920 SECR order for ten K class locomotives. The order was still outstanding in 1924, although most of the component parts had been made. On 14 January 1925, Maunsell ordered No. 790 to be overhauled and trialled on the Central section. As the locomotive proved suitable for the operating conditions of this section, the Southern Railway's Locomotive Committee proceeded with the assembly of the K class parts using outside contractors. Nine sets of parts (Nos. A791–A799) were conveyed to Armstrong Whitworth
for assembly and the finished locomotives delivered in May and June 1925. These were dual-fitted with vacuum
and Westinghouse
(air) brakes for use with the former London, Brighton and South Coast Railway
(LBSCR) rolling stock on the Central section. Other differences from the prototype included the relocation of the regulator to the dome and an increase in superheater area. The tenth set of parts was retained by Ashford and used for the first member of the K1 class later that year.
In May 1925 Maunsell ordered a further ten locomotives from Brighton works
(Nos. A800–A809), which only had vacuum brakes for the SECR stock on the Eastern section. They were delivered between July and December 1926. This group had modified suspension on the bogie and leading axle, in an attempt to address complaints from the crews of rough riding experienced with earlier members of the class. A further 20 members of the class were ordered in March 1926 (ten each from Ashford and Brighton works), despite strong reservations expressed by the Operating Department concerning "the wisdom or desirability of placing so many large passenger tanks in service". These were allocated the numbers A610–A629, and work had begun on building the frames and cylinders when the order was cancelled following an accident at Sevenoaks in 1927
involving locomotive No. A800. These numbers were later allocated to the first production batch of U class locomotives.
wheel arrangement for heavy shunting of freight wagons. They were to use the same boiler as the K and N classes and the general layout was similar to designs used by the GWR in South Wales. Nothing came of this proposal because of other commitments and the absorption of the SECR into the Southern Railway. In 1922, Holcroft suggested that 3-cylinder 2-6-0 tender locomotives with 6 ft (1,828.8 mm) driving wheels should be built instead of tank locomotives. Despite the benefit of a greater operational range, Holcroft's immediate superior, Clayton, refused to pass this suggestion on to Maunsell. The 3-cylinder principle was therefore applied to the K class.
At the Southern Railway’s January 1925 Locomotive Committee meeting, when it was decided to use outside contractors to build the K class, Maunsell received authority to retain one set of parts at Ashford works to construct a prototype 3-cylinder 2-6-4 tank. The modification was based upon that used on N class No. 822 to produce a 3-cylinder locomotive in 1922, although it retained the 6 ft (1,828.8 mm) driving wheels and shorter wheelbase of the K class. The modification was the inclusion of an additional (inside) cylinder between the frames, and a crank axle was fitted to the middle driving wheels. The axle was connected to the inside cylinder assembly by a connecting rod
inclined at 1 in 8 to clear the front driving axle. This arrangement was supplemented by two smaller-diameter outside cylinders with 16 in (406.4 mm) bore (compared to the 19 in (482.6 mm) cylinders of the K class), and a greater chimney diameter. The resulting prototype 3-cylinder "K1" was narrower than the K class and hence could work on routes with restricted loading gauge
. As with No. 822, this locomotive used Holcroft's derivative
of the Gresley conjugated valve gear
to drive the inside cylinder. To accommodate this, the boiler had to be raised by 3 in (76.2 mm) above the inside gear, raising the centre of gravity on the locomotive.
The main visual difference between the K and K1 classes was at the front end: the K1 incorporated a vertical metal cover above the front buffer beam to protect the third cylinder and associated Holcroft valve gear assembly from the elements. It also featured a new cab design with redesigned single front spectacle plates, and a pair of substantially-constructed steps were fitted behind both outside cylinders to provide access to the running plate. The lack of a middle cylinder on the K class locomotives had allowed the provision of a footplate that curved from the buffers to the water tanks. The K1 prototype emerged from Ashford works as No. A890, and underwent trials from 1 December 1925 before entering regular service. Only one locomotive of the K1 class was built; plans to build a further ten (Nos. A891-A900) alongside a batch of five N1 class 2-6-0s were cancelled after the Sevenoaks accident in August 1927. Following rebuilding as a 2-6-0 tender locomotive in 1928, No. A890 was reclassified U1 and was the forerunner of twenty more basically similar locomotives built in 1931.
The K class prototype operated without a name until 1925, when the Southern Railway's publicity department decided to name all express passenger locomotives. The locomotives constructed from 1925 were named after rivers found within the Southern Railway's operating area, and the class became known collectively as the River class. The first-completed Southern Railway K class No. A791 was named River Adur whilst the former SECR prototype was given the name River Avon; names were also allocated to the cancelled 1926 batch of locomotives. The K1 class locomotive No. A890 was named River Frome. The names were displayed on a rectangular brass nameplate fitted to the water tank sides.
The Southern Railway's motive power re-organisation following the Grouping
of 1923 expanded the class for operations over the Central section. The Westinghouse-fitted Armstrong Whitworth batch was used on the air-braked and expresses and regular passenger service trains to Portsmouth
. The vacuum-braked Brighton batch was run-in on the Portsmouth route in preparation for operating the Redhill–Reading line
, the class regularly hauling the daily Birkenhead
–Dover through train. The K1 was mainly rostered to haul the early evening express from Cannon Street to Dover Marine.
(LSWR) routes west of London. The need to save weight meant that compromises were made in some aspects of the design. The boiler size was constrained by the SECR’s axle-loading restrictions, with the result that the design’s full steaming potential was not realised. The failure to capitalise upon a larger boiler would also affect Maunsell’s subsequent 2-6-0 classes, as they were given the same boiler despite their lower axle-loadings.
On the Southern Railway's Central and Eastern sections, crews complained that the locomotives rolled heavily and unpredictably on the cheaply-laid track of the former SECR and LBSCR networks, leading to their nickname, "Rolling Rivers". The rolling was in part caused by the type of coil suspension and steadying springs used on the Bissel truck and bogie axles, which caused adverse springing on poor track. These were modified in later batches, with limited success. The rough-riding was also attributed to the frames
, which were of insubstantial construction to save weight. The bracing proved incapable of counteracting the stresses applied to the frames when travelling at speed and caused excessive vibration on the footplate at higher outputs.
The K1 prototype was slightly faster and more powerful than the K class, and gave a smoother ride at low speeds. It was also found to have a wider route availability due to the smaller outside cylinders. However, the Holcroft valve gear
proved to be difficult to maintain in everyday service. This locomotive was also noted for particularly poor riding characteristics at high speed, derailing twice in 1927. The first derailment occurred at , near Maidstone
on 31 March, when the flanges of the lead coupled wheel mounted the rails at 60 mph (26.8 m/s). The second derailment was at on 20 August, when the lead driving wheel mounted and completely dropped off the rails at 40 mph (17.9 m/s), derailing the train and causing serious damage to the track. These derailments were attributed to the slightly higher centre of gravity of the boiler on the K1. Although the official reports of these accidents blamed the poor quality of the track, a group of directors sought to have both classes banned from use on passenger services, but were overruled by the Southern Railway's Chairman of the Board of Directors, Everard Baring
on grounds of cost.
, Kent
, in August 1927, caused by a combination of a surge in the water tanks and the flanges of the locomotive's lead driving wheels mounting the rail at speed due to poor quality track-work. The locomotive was hauling a Cannon Street to express with a Pullman carriage
when the leading driving wheels derailed at 55 mph (24.6 m/s) over catch points in a cutting. Several carriages were flung against a road bridge, injuring 40 and killing 13 passengers.
In the days following the accident, two K and K1 class engines were trialled on the London and North Eastern Railway
's (LNER) Great Northern
mainline under the supervision of that company's CME, Nigel Gresley
, to gain an unbiased review of their riding qualities. Locomotives No. A803 (K) and No. A890 (K1), and King Arthur class
No. E782, were tested on the well-maintained LNER line between and in October 1927, where few problems were found with locomotive stability. On runs between and with the LNER's dynamometer car
, No. A890 was recorded at a top speed of 83 miles per hour (133.6 km/h) and A803 at 79 miles per hour (127.1 km/h), with no problems in riding. When these engines returned from the LNER, the Southern Railway's General Manager, Sir Herbert Walker
ordered further trials to be led by Sir John Aspinall
on the Western section main line near . These were terminated by the Southern Railway's Operating Department, as the riding of the locomotives at speeds near 80 miles per hour (128.7 km/h) rendered the locomotives unsafe. The instability of No. A890 at speed was attributed to the helical springs on the Bissel truck and bogie.
The 1928 accident inquiry did not attach blame to the Southern Railway for track maintenance or locomotive performance issues, and noted that the prototype had run for eight years over the same stretch of line without complaint. However, it identified the Brighton batch and No. A890 as being more susceptible to rolling on sharp curves with weak rail joints, although the entire class operated without incident on the former LBSCR network. The management of the Southern Railway realised that to have any success in operating the K class tanks on other parts of the network, vast stretches of track would require upgrading. With the prospect of storing 20 locomotives whilst the necessary upgrading took place, the management recommended the class be fully withdrawn from service. To recoup the expense of constructing the engines, Maunsell was given permission to rebuild them to the new SR U class 2-6-0 tender engine design in 1928. This decision also reduced the adverse publicity generated by the accident. However, many of the components discarded during the rebuilding process would later be re-used on another 2-6-4 tank locomotive designed to haul heavy freight on short trips: the 3-cylinder W class of 1932.
The rebuilding of the class as tender locomotives was cheaper than relaying track, particularly as in most respects the class had performed well. Rebuilding took place at Ashford, Brighton and Eastleigh railway works between March and December 1928, where the water tanks, rear bogie and coal bunker were removed. The straight-sided 3500 gallons (15,911.3 l) variant of Maunsell tender was attached, allowing a greater operational range for the locomotives. The rear bogies were later used on the SR W class 2-6-4 tank locomotives (the only subsequent use of this wheel arrangement by the Southern Railway, and their use was restricted to freight operations around London). The solitary K1 class locomotive was rebuilt in June 1928, and so became the three-cylinder prototype of the SR U1 class. The Holcroft valve gear
was later replaced with a third set of Walschaerts valve gear in February 1932, thus reducing maintenance. None of the rebuilds retained their names.
as well as secondary passenger duties on lines between the main routes. They were used all over the Southern Railway network, but were little-used over the steep track gradients west of Exeter. The smaller-wheeled N class was preferred amongst crews for the same duties, as high-speed running was rare away from the main lines in the West Country
. Heavier passenger work was allocated to Bulleid's Unrebuilt Light Pacifics, which were within weight restrictions in this area. The 21 rebuilt locomotives entered British Railways service in 1948. From 1955 a few were given replacement frames
at overhaul: these had a shallower curve between the front buffer beam and the smokebox.
Withdrawals took place between 1962 and 1966, by which time many of the rebuilds were based at Guildford
shed
. Work was taken over by Oliver Bulleid
's Light Pacifics, and the electrification of much of the former Southern Railway network was imminent, making all the 2-6-0s surplus to requirements from 1963. The final rebuild was withdrawn from service in June 1966.
in 1923, the SR replaced the liveries of the constituent companies with a standard sage green livery (the colour being that previously used by Urie on the LSWR
) with black and white lining, primrose yellow numbering and "Southern" on the tender. From 1925, the K and K1 classes were repainted in a darker olive green livery, introduced by Maunsell, with plain white lining and primrose yellow markings. When rebuilt into the U and U1 classes, the locomotives were repainted in the olive green livery with "Southern" added to the tender tank. This was carried into the Second World War when labour shortages meant that many U class locomotives were painted in plain black, with the result that by 1945 all the class were running in black.
The class prototype was initially numbered 790, with the rest following consecutively with a prefix "A" to denote a locomotive designed for the former SECR. The system of prefixes had been adopted by the SR to distinguish between locomotives with identical numbers acquired from different companies, and the K1 class became No. A890 when built in 1925. This system was replaced from 1928 by a renumbering of all locomotives into one sequence, in which the K class rebuilds became Nos. 1790–1809, and the K1 class rebuild became No. 1890.
Sir Nigel Gresley's independent report on the K and K1 classes during the mainline stability trials stated that they were well designed, mechanically reliable and capable of hauling expresses at high speeds on well-maintained track, which meant that they could have been useful additions to the Southern Railway's suburban commuter fleet. However, they were undoubtedly prone to rough riding and instability, and not only on the poorest quality tracks. The restricted water capacity also limited their use outside the Southern Railway's Central section. The impending electrification of the Brighton Main Line
, scheduled for 1932 also meant that fewer duties suitable for heavy passenger tank locomotives would be available in the 1930s. The lack of a suitable role for both classes was considered when the decision was made to rebuild them as U/U1 tender engines following the Sevenoaks disaster. In rebuilt form they continued to operate until the 1960s, and were capable of attaining speeds in excess of 70 mph (110 km/h) with a greater degree of stability.
One K class rebuild has survived: No. A806 River Torridge – converted to U class No. 1806 – was rescued from Woodham Brothers scrap yard in Barry, Vale of Glamorgan, South Wales
in October 1976 for use on the Watercress Line
. It was restored to ex-British Railways condition as No. 31806 and is under overhaul as of November 2009.
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...
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 express passenger 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). The Southern Railway (SR) K1 class was a three-cylinder variant of the K class, designed in 1925 to suit a narrower loading gauge
Loading gauge
A loading gauge defines the maximum height and width for railway vehicles and their loads to ensure safe passage through bridges, tunnels and other structures...
. They were among 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) types to use and improve upon the basic design principles of power and standardisation 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
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:...
. The locomotives were 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...
, improved by the 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....
's ideals of simplicity and ease of maintenance.
The K class was designed to be mechanically similar to the SECR N class 2-6-0
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...
mixed-traffic locomotives. The class was the earliest large-scale use of the 2-6-4 wheel arrangement in Britain. Production began towards the end of the First World War, and the prototype 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...
three years after design work was completed due to wartime production constraints. The class replaced 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...
passenger locomotives in an SECR fleet standardisation programme.
Twenty-one locomotives were built: twenty K class (two cylinders) and one K1 class (three cylinders), the first in 1917 and the remainder between 1925 and 1926. They operated over the Eastern section of the Southern Railway network and were given the names of rivers, being referred as the River class from 1925. Crews referred to the K and K1 classes as "Rolling Rivers" because of their instability when travelling at speed. They were rebuilt as 2-cylinder SR U class and 3-cylinder SR U1 class 2-6-0s (respectively) following a railway accident at Sevenoaks, Kent
Sevenoaks railway accident
The Sevenoaks railway accident occurred on 24 August 1927 between Dunton Green railway station and Sevenoaks railway station. The Southern Railway's afternoon express from Cannon Street to Deal left London at 5pm, in charge of River Class tank engine No 800 River Cray. Several passengers later...
in 1927. They continued in service with British Railways (BR) until the last was withdrawn in 1966. One K class rebuild 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 and as of 2009 was being overhauled.
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): the heavy passenger train loadings; the poor track quality; and the weak, lightly built bridges. 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) – inherited by the SECR in 1899 – beach pebbles 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...
instead of conventional ballast, which has irregular shapes that lock together to keep the track in place. These economies in construction meant that only locomotives with low axle loadings could operate safely over the track. The SECR was therefore unable to follow a coherent strategy to reduce the number of locomotive types inherited from the two constituent railways. Despite increased passenger and freight traffic between and the 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...
ish coast during the first decades of the 20th century, the 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, which could operate within the restrictions imposed by the infrastructure. This resulted in 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....
, adding to operational costs.
Richard Maunsell was appointed CME of the SECR in 1913, following the enforced 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...
, who had left a range of competent but unspectacular locomotive classes that struggled to cope with the increased train lengths and loadings. Maunsell reviewed the situation and planned to introduce six standard classes – using only two boiler designs – which would work the entire traffic of the railway. The first of these was the N class 2-6-0
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...
, which gave the SECR a capable mixed-traffic locomotive
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...
. For the express passenger design that could cope with the heavy boat train
Boat train
A boat train is a passenger train which connects with a passenger ship, such as a ferry or ocean liner. Through ticketing is normally available. -Notable named boat trains:*The Flèche d'Or Paris Gare du Nord to Calais...
s, Maunsell wanted to enlarge the existing L class
SECR L class
The SECR L class was a class of 4-4-0 steam tender locomotive built for express passenger service on the South Eastern and Chatham Railway. Although designed by Harry Wainwright, they were built during the Maunsell era.-Background:...
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...
with Walschaerts valve gear and an enlarged 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...
, but this design would have resulted in a too heavy axle loading. Maunsell's newly recruited assistants, G.H. Pearson and 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...
from the 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...
at Swindon and James Clayton from the 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....
at Derby, had recently been involved in the design of large passenger tank engines and persuaded him to use the 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...
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...
, which would allow the class to operate at high speeds on the poor-quality track in north Kent.
Design and construction
The 2-6-4 wheel arrangement was not in common use in Great Britain at this time, as many railway companies operated routes that required locomotives with greater fuel capacity, or short branch lines that necessitated smaller locomotives. The 2-6-4 tank engine design had only been used once before for standard gaugeStandard gauge
The standard gauge is a widely-used track gauge . Approximately 60% of the world's existing railway lines are built to this gauge...
locomotives in Britain, on the Great Central Railway
Great Central Railway
The Great Central Railway was a railway company in England which came into being when the Manchester, Sheffield and Lincolnshire Railway changed its name in 1897 in anticipation of the opening in 1899 of its London Extension . On 1 January 1923, it was grouped into the London and North Eastern...
's 1B class
GCR Class 1B
The GCR Class 1B was a class of 2-6-4T locomotives on the Great Central Railway. They were notable as the first locomotives of the 2-6-4T wheel arrangement to be used by a British standard-gauge railway; there had been two narrow-gauge examples on the Leek & Manifold Valley Light Railway since...
freight locomotives of 1914. However, the configuration was ideal for the SECR, because of its shorter mainlines, and allowed for a long wheelbase with a leading axle to permit greater stability at speed on track curves. The tightness of the curves on the former LCDR mainlines had constrained the size of locomotives operating on the SECR, as they had been hastily erected during the nineteenth century to compete with those of the South Eastern Railway
South Eastern Railway (UK)
The South Eastern Railway was a railway company in south-eastern England from 1836 until 1922. The company was formed to construct a route from London to Dover. Branch lines were later opened to Tunbridge Wells, Hastings, Canterbury and other places in Kent...
(SER). The 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 a 4-4-0, giving sufficient power to avoid double-heading of locomotives on heavier trains.
The K class design used a "Bissel bogie
Bissel bogie
A Bissel truck is a very simple and commonly used way of designing a carrying axle on a steam locomotive to enable it to negotiate curves more easily. The design uses a single-axled bogie, usually known as a pony truck, whose pivot is towards the centre of the locomotive...
" leading axle and a plain trailing 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...
. The trailing bogie permitted the use of a large coal bunker that was capable of sustaining the locomotive over the run between London Charing Cross and , and side water tanks of 2000 imp gal (9,092.2 l) capacity were used, negating the need for a tender. The coupled wheelbase between the rear and centre driving wheels was reduced from that used on the mechanically identical N class to 7 in 9 in (2.36 m) to accommodate the bogie. The cab was fully enclosed, although the set of four small front spectacle plates (the windows on the front face of the cab for forward visibility) were the same as those used on the N class.
The K class was designed by Maunsell's team in 1914 as part of his proposed standardisation programme following the N class, but the designs were not shown to the railway directors until early 1915 to enable all six designs to be shown at once. The design 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 at high speeds, 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. The inclusion of these features is attributed to Holcroft, Maunsell's personal assistant, who had 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...
and the N class. James Clayton, Maunsell's Chief Locomotive Draughtsman, brought simpler and more 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. The latter was fitted with Ross pop 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....
s and pressed to 200 psi (1.38 MPa).
Other innovations by Maunsell's team included greater superheating
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...
surface area, 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, outside Walschaerts valve gear, and parts that could be shared with similar locomotive classes to reduce maintenance costs. The firebox was narrower towards the rear and featured a continuously sloping grate, whilst the ashpan was fitted with front and rear damper doors, the latter adjusted to clear the rear driving axle. The lower part of the coal bunker incorporated a water tank of 760 imp gal (3,455 l) capacity. This was connected to two 620 imp gal (2,818.6 l) side tanks
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...
by two rectangular pipes on either side of the locomotive that also formed supports for the cab 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...
.
K class
In January 1915 Maunsell received authority to build six examples, but, as with the N class, production was delayed due to the use of the Ashford worksAshford 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...
for wartime armaments manufacture. Assembly began in 1917 and the first, No. 790, emerged in July of that year. It was based at Bricklayers Arms depot, preceding the earlier N class design into service by one month. Further construction was deferred until after Ashford had caught up with the maintenance backlog caused by the war.
Ten more locomotives were ordered by the SECR from Ashford works in June 1920, and to speed delivery the construction of 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...
, cylinders and side tanks was subcontracted to 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...
at 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...
. However, further severe delays at Ashford caused by the backlog of repair work meant that the boilers had to be supplied by 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...
. Construction of these locomotives had not begun by 1 January 1923, when the Railways Act 1921
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...
merged the SECR with other railways in southern England to form the 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...
.
Maunsell was appointed CME of the newly formed Southern Railway in 1923, and inherited the 1920 SECR order for ten K class locomotives. The order was still outstanding in 1924, although most of the component parts had been made. On 14 January 1925, Maunsell ordered No. 790 to be overhauled and trialled on the Central section. As the locomotive proved suitable for the operating conditions of this section, the Southern Railway's Locomotive Committee proceeded with the assembly of the K class parts using outside contractors. Nine sets of parts (Nos. A791–A799) were conveyed to Armstrong Whitworth
Armstrong Whitworth
Sir W G Armstrong Whitworth & Co Ltd was a major British manufacturing company of the early years of the 20th century. Headquartered in Elswick, Newcastle upon Tyne, Armstrong Whitworth engaged in the construction of armaments, ships, locomotives, automobiles, and aircraft.-History:In 1847,...
for assembly and the finished locomotives delivered in May and June 1925. These were dual-fitted with vacuum
Vacuum brake
The vacuum brake is a braking system employed on trains and introduced in the mid-1860s. A variant, the automatic vacuum brake system, became almost universal in British train equipment and in those countries influenced by British practice. Vacuum brakes also enjoyed a brief period of adoption in...
and Westinghouse
Westinghouse Air Brake Company
The railway air brake was invented by George Westinghouse of New York state in 1869. Soon after, he moved to Pittsburgh, Pennsylvania, where he established the Westinghouse Air Brake Company on September 28, 1869...
(air) brakes for use with the former London, Brighton and South Coast Railway
London, Brighton and South Coast Railway
The London, Brighton and South Coast Railway was a railway company in the United Kingdom from 1846 to 1922. Its territory formed a rough triangle, with London at its apex, practically the whole coastline of Sussex as its base, and a large part of Surrey...
(LBSCR) rolling stock on the Central section. Other differences from the prototype included the relocation of the regulator to the dome and an increase in superheater area. The tenth set of parts was retained by Ashford and used for the first member of the K1 class later that year.
In May 1925 Maunsell ordered a further ten locomotives from Brighton works
Brighton railway works
Brighton railway works was one of the earliest railway-owned locomotive repair works, founded in 1840 by the London and Brighton Railway in Brighton, England, and thus pre-dating the more famous railway works at Crewe, Doncaster and Swindon...
(Nos. A800–A809), which only had vacuum brakes for the SECR stock on the Eastern section. They were delivered between July and December 1926. This group had modified suspension on the bogie and leading axle, in an attempt to address complaints from the crews of rough riding experienced with earlier members of the class. A further 20 members of the class were ordered in March 1926 (ten each from Ashford and Brighton works), despite strong reservations expressed by the Operating Department concerning "the wisdom or desirability of placing so many large passenger tanks in service". These were allocated the numbers A610–A629, and work had begun on building the frames and cylinders when the order was cancelled following an accident at Sevenoaks in 1927
Sevenoaks railway accident
The Sevenoaks railway accident occurred on 24 August 1927 between Dunton Green railway station and Sevenoaks railway station. The Southern Railway's afternoon express from Cannon Street to Deal left London at 5pm, in charge of River Class tank engine No 800 River Cray. Several passengers later...
involving locomotive No. A800. These numbers were later allocated to the first production batch of U class locomotives.
K1 class
In August 1919, a proposal was put to the SECR’s Locomotive, Carriage and Wagon Committee for 2 and 3-cylinder tank engines of 2-8-02-8-0
Under the Whyte notation for the classification of steam locomotives, 2-8-0 represents the wheel arrangement of two leading wheels on one axle , eight powered and coupled driving wheels on four axles, and no trailing wheels...
wheel arrangement for heavy shunting of freight wagons. They were to use the same boiler as the K and N classes and the general layout was similar to designs used by the GWR in South Wales. Nothing came of this proposal because of other commitments and the absorption of the SECR into the Southern Railway. In 1922, Holcroft suggested that 3-cylinder 2-6-0 tender locomotives with 6 ft (1,828.8 mm) driving wheels should be built instead of tank locomotives. Despite the benefit of a greater operational range, Holcroft's immediate superior, Clayton, refused to pass this suggestion on to Maunsell. The 3-cylinder principle was therefore applied to the K class.
At the Southern Railway’s January 1925 Locomotive Committee meeting, when it was decided to use outside contractors to build the K class, Maunsell received authority to retain one set of parts at Ashford works to construct a prototype 3-cylinder 2-6-4 tank. The modification was based upon that used on N class No. 822 to produce a 3-cylinder locomotive in 1922, although it retained the 6 ft (1,828.8 mm) driving wheels and shorter wheelbase of the K class. The modification was the inclusion of an additional (inside) cylinder between the frames, and a crank axle was fitted to the middle driving wheels. The axle was connected to the inside cylinder assembly by a connecting rod
Connecting rod
In a reciprocating piston engine, the connecting rod or conrod connects the piston to the crank or crankshaft. Together with the crank, they form a simple mechanism that converts linear motion into rotating motion....
inclined at 1 in 8 to clear the front driving axle. This arrangement was supplemented by two smaller-diameter outside cylinders with 16 in (406.4 mm) bore (compared to the 19 in (482.6 mm) cylinders of the K class), and a greater chimney diameter. The resulting prototype 3-cylinder "K1" was narrower than the K class and hence could work on routes with restricted loading gauge
Loading gauge
A loading gauge defines the maximum height and width for railway vehicles and their loads to ensure safe passage through bridges, tunnels and other structures...
. As with No. 822, this locomotive used Holcroft's derivative
Holcroft valve gear
The Holcroft valve gear was a type of valve gear designed by Harold Holcroft and used on three-cylinder steam locomotives of the South Eastern and Chatham Railway . It bore many similarities to the Gresley conjugated valve gear used on the original LNER A1 design...
of the Gresley conjugated valve gear
Gresley conjugated valve gear
The Gresley conjugated valve gear is a valve gear for steam locomotives designed by Sir Nigel Gresley, chief mechanical engineer of the LNER, assisted by Harold Holcroft...
to drive the inside cylinder. To accommodate this, the boiler had to be raised by 3 in (76.2 mm) above the inside gear, raising the centre of gravity on the locomotive.
The main visual difference between the K and K1 classes was at the front end: the K1 incorporated a vertical metal cover above the front buffer beam to protect the third cylinder and associated Holcroft valve gear assembly from the elements. It also featured a new cab design with redesigned single front spectacle plates, and a pair of substantially-constructed steps were fitted behind both outside cylinders to provide access to the running plate. The lack of a middle cylinder on the K class locomotives had allowed the provision of a footplate that curved from the buffers to the water tanks. The K1 prototype emerged from Ashford works as No. A890, and underwent trials from 1 December 1925 before entering regular service. Only one locomotive of the K1 class was built; plans to build a further ten (Nos. A891-A900) alongside a batch of five N1 class 2-6-0s were cancelled after the Sevenoaks accident in August 1927. Following rebuilding as a 2-6-0 tender locomotive in 1928, No. A890 was reclassified U1 and was the forerunner of twenty more basically similar locomotives built in 1931.
K and K1 class construction history
| Year | Batch | Quantity | SECR/SR numbers | Class |
|---|---|---|---|---|
| 1917 | |
|
790 | |
| 1925 | |
|
A791–A799 | |
| 1925 | 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... (Ashford Works) |
|
A890 | |
| 1926 | 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... (Brighton Works) |
|
A800–A809 | |
Naming the locomotives
- For details of K and K1 class locomotive names, see: List of SECR K and SR K1 class locomotives
The K class prototype operated without a name until 1925, when the Southern Railway's publicity department decided to name all express passenger locomotives. The locomotives constructed from 1925 were named after rivers found within the Southern Railway's operating area, and the class became known collectively as the River class. The first-completed Southern Railway K class No. A791 was named River Adur whilst the former SECR prototype was given the name River Avon; names were also allocated to the cancelled 1926 batch of locomotives. The K1 class locomotive No. A890 was named River Frome. The names were displayed on a rectangular brass nameplate fitted to the water tank sides.
Operational details
The K class was intended to haul the SECR's Kent expresses, and was trialled between Charing Cross, , and . A trial non-stop run between and by No. 790 pulling a train of 300 LT had proved the water capacity of the side tanks to be insufficient for such runs. No. 790 was also tested on fast Cannon Street, and Tonbridge trains during the spring of 1922, although rough riding between the latter two stations meant slower speeds over that part of route on subsequent runs.The Southern Railway's motive power re-organisation following the Grouping
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...
of 1923 expanded the class for operations over the Central section. The Westinghouse-fitted Armstrong Whitworth batch was used on the air-braked and expresses and regular passenger service trains to Portsmouth
Portsmouth and Southsea railway station
Portsmouth and Southsea railway station is the main railway station in central Portsmouth in Hampshire, England. It is close to the Commercial Road shopping centre....
. The vacuum-braked Brighton batch was run-in on the Portsmouth route in preparation for operating the Redhill–Reading line
North Downs Line
The North Downs Line is the name of the passenger train service connecting Reading, on the Great Western Main Line, to Gatwick Airport, on the Brighton Main Line...
, the class regularly hauling the daily Birkenhead
Birkenhead Woodside railway station
Birkenhead Woodside was a railway station at Woodside, in Birkenhead, on the Wirral Peninsula, England.-Background:Birkenhead Woodside railway station was opened on 31 March 1878 to replace the increasingly inadequate passenger facilities provided at Birkenhead Monks Ferry station.It was built...
–Dover through train. The K1 was mainly rostered to haul the early evening express from Cannon Street to Dover Marine.
Performance of the tank locomotives
The K class proved successful on well-maintained track. It was capable of high speeds on express passenger duties, although their use was limited by the lower storage capacity of tank locomotives, which meant the K and K1 classes were prone to water shortages on the long Kent Coast routes, and precluded them from working many of the former London and South Western RailwayLondon 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...
(LSWR) routes west of London. The need to save weight meant that compromises were made in some aspects of the design. The boiler size was constrained by the SECR’s axle-loading restrictions, with the result that the design’s full steaming potential was not realised. The failure to capitalise upon a larger boiler would also affect Maunsell’s subsequent 2-6-0 classes, as they were given the same boiler despite their lower axle-loadings.
On the Southern Railway's Central and Eastern sections, crews complained that the locomotives rolled heavily and unpredictably on the cheaply-laid track of the former SECR and LBSCR networks, leading to their nickname, "Rolling Rivers". The rolling was in part caused by the type of coil suspension and steadying springs used on the Bissel truck and bogie axles, which caused adverse springing on poor track. These were modified in later batches, with limited success. The rough-riding was also attributed to 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...
, which were of insubstantial construction to save weight. The bracing proved incapable of counteracting the stresses applied to the frames when travelling at speed and caused excessive vibration on the footplate at higher outputs.
The K1 prototype was slightly faster and more powerful than the K class, and gave a smoother ride at low speeds. It was also found to have a wider route availability due to the smaller outside cylinders. However, the Holcroft valve gear
Holcroft valve gear
The Holcroft valve gear was a type of valve gear designed by Harold Holcroft and used on three-cylinder steam locomotives of the South Eastern and Chatham Railway . It bore many similarities to the Gresley conjugated valve gear used on the original LNER A1 design...
proved to be difficult to maintain in everyday service. This locomotive was also noted for particularly poor riding characteristics at high speed, derailing twice in 1927. The first derailment occurred at , near Maidstone
Maidstone
Maidstone is the county town of Kent, England, south-east of London. The River Medway runs through the centre of the town linking Maidstone to Rochester and the Thames Estuary. Historically, the river was a source and route for much of the town's trade. Maidstone was the centre of the agricultural...
on 31 March, when the flanges of the lead coupled wheel mounted the rails at 60 mph (26.8 m/s). The second derailment was at on 20 August, when the lead driving wheel mounted and completely dropped off the rails at 40 mph (17.9 m/s), derailing the train and causing serious damage to the track. These derailments were attributed to the slightly higher centre of gravity of the boiler on the K1. Although the official reports of these accidents blamed the poor quality of the track, a group of directors sought to have both classes banned from use on passenger services, but were overruled by the Southern Railway's Chairman of the Board of Directors, Everard Baring
Everard Baring
Brigadier-General, The Hon. Everard Baring was a Chairman of the Southern Railway.Baring was one of ten children of Edward Charles Baring and Louisa Emily Charlotte Baring . He was educated at Eton College and at the Royal Military College at Sandhurst...
on grounds of cost.
Sevenoaks disaster
The K and K1 classes suffered from stability problems when travelling at speed over points and curves. The locomotive would initially roll (briefly lean heavily) to one side, followed by several further rolls of gradually reducing amplitude, combined with a side-slipping movement that caused the driving wheels to mount the rails. Several minor derailments of members of the class culminated in the serious derailment of No. A800 River Cray at SevenoaksSevenoaks railway accident
The Sevenoaks railway accident occurred on 24 August 1927 between Dunton Green railway station and Sevenoaks railway station. The Southern Railway's afternoon express from Cannon Street to Deal left London at 5pm, in charge of River Class tank engine No 800 River Cray. Several passengers later...
, 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...
, in August 1927, caused by a combination of a surge in the water tanks and the flanges of the locomotive's lead driving wheels mounting the rail at speed due to poor quality track-work. The locomotive was hauling a Cannon Street to express with a Pullman carriage
Pullman (car or coach)
In the United States, Pullman was used to refer to railroad sleeping cars which were built and operated on most U.S. railroads by the Pullman Company from 1867 to December 31, 1968....
when the leading driving wheels derailed at 55 mph (24.6 m/s) over catch points in a cutting. Several carriages were flung against a road bridge, injuring 40 and killing 13 passengers.
In the days following the accident, two K and K1 class engines were trialled on the London and North Eastern Railway
London and North Eastern Railway
The London and North Eastern Railway was the second-largest of the "Big Four" railway companies created by the Railways Act 1921 in Britain...
's (LNER) Great Northern
Great Northern Railway (Great Britain)
The Great Northern Railway was a British railway company established by the Great Northern Railway Act of 1846. On 1 January 1923 the company lost its identity as a constituent of the newly formed London and North Eastern Railway....
mainline under the supervision of that company's CME, Nigel Gresley
Nigel Gresley
Sir Herbert Nigel Gresley was one of Britain's most famous steam locomotive engineers, who rose to become Chief Mechanical Engineer of the London and North Eastern Railway . He was the designer of some of the most famous steam locomotives in Britain, including the LNER Class A1 and LNER Class A4...
, to gain an unbiased review of their riding qualities. Locomotives No. A803 (K) and No. A890 (K1), and 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...
No. E782, were tested on the well-maintained LNER line between and in October 1927, where few problems were found with locomotive stability. On runs between and with the LNER's dynamometer car
Dynamometer car
A dynamometer car is a railroad maintenance of way car used for measuring various aspects of a locomotive's performance. Measurements include tractive effort , power, top speed, etc.-History:...
, No. A890 was recorded at a top speed of 83 miles per hour (133.6 km/h) and A803 at 79 miles per hour (127.1 km/h), with no problems in riding. When these engines returned from the LNER, the Southern Railway's General Manager, Sir Herbert Walker
Herbert Ashcombe Walker
Sir Herbert Ashcombe Walker, KCB was a British railway manager.-Early life:Walker was born in London 15 May 1868. He was educated at the North London Collegiate School and at Bruges.-Career:...
ordered further trials to be led by Sir John Aspinall
John Aspinall (engineer)
Sir John Audley Frederick Aspinall was a British mechanical engineer who served as Locomotive Superintendent of the Great Southern and Western and Lancashire and Yorkshire Railways. He introduced vacuum brakes to his locomotives in Ireland, a trend which was followed in Britain, and designed...
on the Western section main line near . These were terminated by the Southern Railway's Operating Department, as the riding of the locomotives at speeds near 80 miles per hour (128.7 km/h) rendered the locomotives unsafe. The instability of No. A890 at speed was attributed to the helical springs on the Bissel truck and bogie.
The 1928 accident inquiry did not attach blame to the Southern Railway for track maintenance or locomotive performance issues, and noted that the prototype had run for eight years over the same stretch of line without complaint. However, it identified the Brighton batch and No. A890 as being more susceptible to rolling on sharp curves with weak rail joints, although the entire class operated without incident on the former LBSCR network. The management of the Southern Railway realised that to have any success in operating the K class tanks on other parts of the network, vast stretches of track would require upgrading. With the prospect of storing 20 locomotives whilst the necessary upgrading took place, the management recommended the class be fully withdrawn from service. To recoup the expense of constructing the engines, Maunsell was given permission to rebuild them to the new SR U class 2-6-0 tender engine design in 1928. This decision also reduced the adverse publicity generated by the accident. However, many of the components discarded during the rebuilding process would later be re-used on another 2-6-4 tank locomotive designed to haul heavy freight on short trips: the 3-cylinder W class of 1932.
Rebuilding
Holcroft valve gear
The Holcroft valve gear was a type of valve gear designed by Harold Holcroft and used on three-cylinder steam locomotives of the South Eastern and Chatham Railway . It bore many similarities to the Gresley conjugated valve gear used on the original LNER A1 design...
was later replaced with a third set of Walschaerts valve gear in February 1932, thus reducing maintenance. None of the rebuilds retained their names.
Performance of the rebuilt locomotives and withdrawal
As members of the U and U1 classes, rebuilds were used mainly on mixed-trafficMixed-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...
as well as secondary passenger duties on lines between the main routes. They were used all over the Southern Railway network, but were little-used over the steep track gradients west of Exeter. The smaller-wheeled N class was preferred amongst crews for the same duties, as high-speed running was rare away from the main lines in the West Country
West Country
The West Country is an informal term for the area of south western England roughly corresponding to the modern South West England government region. It is often defined to encompass the historic counties of Cornwall, Devon, Dorset and Somerset and the City of Bristol, while the counties of...
. Heavier passenger work was allocated to Bulleid's Unrebuilt Light Pacifics, which were within weight restrictions in this area. The 21 rebuilt locomotives entered British Railways service in 1948. From 1955 a few were given replacement 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...
at overhaul: these had a shallower curve between the front buffer beam and the smokebox.
Withdrawals took place between 1962 and 1966, by which time many of the rebuilds were based at 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....
shed
Motive power depot
Motive power depot, usually abbreviated to MPD, is a name given to places where locomotives are stored when not being used, and also repaired and maintained. They were originally known as "running sheds", "engine sheds", or, for short, just sheds. Facilities are provided for refuelling and...
. Work was taken over by 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,...
's Light Pacifics, and the electrification of much of the former Southern Railway network was imminent, making all the 2-6-0s surplus to requirements from 1963. The final rebuild was withdrawn from service in June 1966.
SECR and Southern Railway
The K class prototype was 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. On GroupingRailways 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...
in 1923, the SR replaced the liveries of the constituent companies with a standard sage green livery (the colour being that previously used by Urie 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. From 1925, the K and K1 classes were repainted in a darker olive green livery, introduced by Maunsell, with plain white lining and primrose yellow markings. When rebuilt into the U and U1 classes, the locomotives were repainted in the olive green livery with "Southern" added to the tender tank. This was carried into the Second World War when labour shortages meant that many U class locomotives were painted in plain black, with the result that by 1945 all the class were running in black.
The class prototype was initially numbered 790, with the rest following consecutively with a prefix "A" to denote a locomotive designed for the former SECR. The system of prefixes had been adopted by the SR to distinguish between locomotives with identical numbers acquired from different companies, and the K1 class became No. A890 when built in 1925. This system was replaced from 1928 by a renumbering of all locomotives into one sequence, in which the K class rebuilds became Nos. 1790–1809, and the K1 class rebuild became No. 1890.
Rebuilds in British Railways service
The K and K1 classes were absorbed by British Railways as part of the U and U1 classes in 1948, which were given the BR power classification 4MT (mixed-traffic) in 1950. This was later revised to 4P3F in the light of operational experience on freight trains. The locomotives at first retained their Southern Railway livery, with "British Railways" added to the tender when repaints were due. From 1949 to 1955, the U and U1 class locomotives were gradually repainted in the British Railways mixed-traffic lined black livery with red, cream and grey lining and the British Railways crest on the tender. Numbers were changed to the British Railways standard numbering system: the series 31790–31809 was allocated to the K class rebuilds, and 31890 to the K1 class.Operational assessment and preservation
- For location details and current status of the preserved (rebuilt) locomotive, see: List of K and K1 class locomotives.
Sir Nigel Gresley's independent report on the K and K1 classes during the mainline stability trials stated that they were well designed, mechanically reliable and capable of hauling expresses at high speeds on well-maintained track, which meant that they could have been useful additions to the Southern Railway's suburban commuter fleet. However, they were undoubtedly prone to rough riding and instability, and not only on the poorest quality tracks. The restricted water capacity also limited their use outside the Southern Railway's Central section. The impending electrification of the Brighton Main Line
Brighton Main Line
The Brighton Main Line is a British railway line from London Victoria and London Bridge to Brighton. It is about 50 miles long, and is electrified throughout. Trains are operated by Southern, First Capital Connect, and Gatwick Express, now part of Southern.-Original proposals:There were no fewer...
, scheduled for 1932 also meant that fewer duties suitable for heavy passenger tank locomotives would be available in the 1930s. The lack of a suitable role for both classes was considered when the decision was made to rebuild them as U/U1 tender engines following the Sevenoaks disaster. In rebuilt form they continued to operate until the 1960s, and were capable of attaining speeds in excess of 70 mph (110 km/h) with a greater degree of stability.
One K class rebuild has survived: No. A806 River Torridge – converted to U class No. 1806 – was rescued from Woodham Brothers scrap yard 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...
in October 1976 for use 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...
. It was restored to ex-British Railways condition as No. 31806 and is under overhaul as of November 2009.
Further reading
- Fryer, Charles: Railway Monographs No.1: The Rolling Rivers (Sheffield: Platform 5 Publishing, 1993) ISBN 1872524397
- Grayer, Jeffery: "Scuppering the "U-Boats"" in Robertson, Kevin: The Southern Way Issue No.7 (Corhampton: Noodle Books (July 2009)), pp. 60–65. ISBN 978 1 906419 17 2.
- Nock, O.S.: Great Locomotives of the Southern Railway (Guild Publishing/Book Club Associates, 1987) pp. 98–102,115,132–137,154–160. CN 5587
- Robertson, Kevin, ed.: "Scuppering the "U-Boats" - Years Earlier" (The Southern Way Issue No. 7: Corhampton, Noodle Books (July 2009)), pp. 66–67. ISBN 978 1 906419 17 2.