LSWR D15 class
Encyclopedia
The LSWR D15 class 4-4-0
was the last steam locomotive
design by Dugald Drummond
for the London and South Western Railway
in 1912.
express passenger locomotives. The result of these failures was that when he designed what was to be his last class in 1911, a new 4-4-0 design emerged from Eastleigh
workshops in February 1912, with what was to be the first of his D15 class.
with wing plates. The boiler
was based on that fitted to the 1905 rebuild of his first double-single, T7 class
number 720 of 1897; and had a long firebox
with a sloping grate
. This resulted in the boiler being pitched higher than usual in order to allow clearance over the trailing axle. An exhaust steam feedwater heater
was provided and the boiler fed by duplex pumps located on the frames, between the coupled wheels. The class was initially given the "intermediate" type of eight-wheel, double bogie tender with inside bogie frames carrying 4 tons (4.06 tonnes) of coal and 4,500 gallons (20.5m3), due to the lack of water troughs on the line.
After Drummond's death, Robert Urie, his successor, fitted the class with Eastleigh superheater
s. These had a very small superheating surface, they were replaced by Maunsell superheaters, when Richard Maunsell
was appointed Chief Mechanical Engineer
of the Southern Railway after the grouping of 1923. By this time, the eight-wheeled tenders had been replaced by six wheeled 3,500 gallon (15.9m3) versions transferred from K10
and L11
locomotives.
, where many drivers noted their superior operational characteristics when compared to the T14 class
4-6-0s. This was due to a marked reduction in coal
, water
and oil
consumption, and easier maintenance. However, with the succession of Urie, no further D15s were constructed, as he preferred to concentrate on 4-6-0 designs.
These successful locomotives worked, in the main, out of Waterloo and prior to electrification had a virtual monopoly of the Portsmouth
expresses. Until the advent of the Bulleid Light Pacifics, a D15 was usually to be found working the Brighton
to Plymouth
service. Number 468 differed from the rest of the class in that it had the safety valve
s mounted on the firebox, with Urie N15
style dome and safety valve casings, whilst the others had Drummond direct-loaded safety valves on their domes. As built, number 463 was fitted with a hooter rather than a whistle
, which it kept until the Second World War. The class continued into British Railways service, though were gradually withdrawn in the early 1950s. This meant that none survived to be preserved.
When transferred to Southern Railway ownership after 1923, the locomotives carried Richard Maunsell's darker version of the LSWR livery. The LSWR standard gilt lettering was changed to yellow with 'Southern' on the water tank sides. The locomotives also featured black and white lining.
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...
was the last 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...
design by 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...
for the London and South Western Railway
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...
in 1912.
Background
By 1912, Dugald Drummond had built several classes of unsuccessful 4-6-04-6-0
Under the Whyte notation for the classification of steam locomotives, 4-6-0 represents the wheel arrangement of four leading wheels on two axles in a leading truck, six powered and coupled driving wheels on three axles, and no trailing wheels. This wheel arrangement became the second-most popular...
express passenger locomotives. The result of these failures was that when he designed what was to be his last class in 1911, a new 4-4-0 design emerged from Eastleigh
Eastleigh
Eastleigh is a railway town in Hampshire, England, and the main town in the Eastleigh borough which is part of Southampton Urban Area. The town lies between Southampton and Winchester, and is part of the South Hampshire conurbation...
workshops in February 1912, with what was to be the first of his D15 class.
Construction history
In line with the typical Drummond layout, the D15s had a short smokeboxSmokebox
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...
with wing plates. The boiler
Boiler
A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications.-Materials:...
was based on that fitted to the 1905 rebuild of his first double-single, T7 class
LSWR T7 class
The LSWR Class T7 4-2-2-0 was a prototype express steam locomotive design by Dugald Drummond for the London and South Western Railway introduced in 1897.-Background:Number 720 was a prototype locomotive built in 1897...
number 720 of 1897; and had a long firebox
Firebox
In a steam engine, the firebox is the area where the fuel is burned, producing heat to boil the water in the boiler. Most are somewhat box-shaped, hence the name.-Railway locomotive firebox :...
with a sloping grate
Grate
*A grate is a frame of iron bars to hold fuel for a fire.*It may also refer to a covering of a drain, also called a grating.*The act of using a grater, a kitchen utensil.- People :*Don Grate US sportsman....
. This resulted in the boiler being pitched higher than usual in order to allow clearance over the trailing axle. An exhaust steam feedwater heater
Feedwater heater
A feedwater heater is a power plant component used to pre-heat water delivered to a steam generating boiler. Preheating the feedwater reduces the irreversibilities involved in steam generation and therefore improves the thermodynamic efficiency of the system...
was provided and the boiler fed by duplex pumps located on the frames, between the coupled wheels. The class was initially given the "intermediate" type of eight-wheel, double bogie tender with inside bogie frames carrying 4 tons (4.06 tonnes) of coal and 4,500 gallons (20.5m3), due to the lack of water troughs on the line.
After Drummond's death, Robert Urie, his successor, fitted the class with Eastleigh 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...
s. These had a very small superheating surface, they were replaced by Maunsell superheaters, when 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....
was 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 after the grouping of 1923. By this time, the eight-wheeled tenders had been replaced by six wheeled 3,500 gallon (15.9m3) versions transferred from K10
LSWR K10 Class
The London and South Western Railway K10 Class was a class of 40 4-4-0 steam locomotives designed for mixed traffic work. They were introduced on the London and South Western Railway in 1901 and 1902 to the design of Dugald Drummond, where they earned the nickname "Small Hoppers".- Background :In...
and L11
LSWR L11 Class
The London and South Western Railway L11 class was a class of 4-4-0 steam locomotives designed for mixed traffic work. They were introduced in 1903 and were nicknamed "Large Hoppers"...
locomotives.
| Year | Order | Quantity | LSWR numbers | Notes |
|---|---|---|---|---|
| 1912 | |
|
463–467 | |
| 1912 | |
|
468–472 | |
Operational details
Contrary to Drummond's previous 4-6-0 designs, the D15s performed exceptionally well and were put to work on trains to BournemouthBournemouth
Bournemouth is a large coastal resort town in the ceremonial county of Dorset, England. According to the 2001 Census the town has a population of 163,444, making it the largest settlement in Dorset. It is also the largest settlement between Southampton and Plymouth...
, where many drivers noted their superior operational characteristics when compared to the T14 class
LSWR T14 class
The LSWR Class T14 was a class of ten 4-6-0 locomotives designed by Dugald Drummond for express passenger use on the London and South Western Railway and constructed at Eastleigh in 1911–12 .- Background :...
4-6-0s. This was due to a marked reduction in coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...
, water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
and oil
Oil
An oil is any substance that is liquid at ambient temperatures and does not mix with water but may mix with other oils and organic solvents. This general definition includes vegetable oils, volatile essential oils, petrochemical oils, and synthetic oils....
consumption, and easier maintenance. However, with the succession of Urie, no further D15s were constructed, as he preferred to concentrate on 4-6-0 designs.
These successful locomotives worked, in the main, out of Waterloo and prior to electrification had a virtual monopoly of the Portsmouth
Portsmouth
Portsmouth is the second largest city in the ceremonial county of Hampshire on the south coast of England. Portsmouth is notable for being the United Kingdom's only island city; it is located mainly on Portsea Island...
expresses. Until the advent of the Bulleid Light Pacifics, a D15 was usually to be found working the Brighton
Brighton
Brighton is the major part of the city of Brighton and Hove in East Sussex, England on the south coast of Great Britain...
to Plymouth
Plymouth
Plymouth is a city and unitary authority area on the coast of Devon, England, about south-west of London. It is built between the mouths of the rivers Plym to the east and Tamar to the west, where they join Plymouth Sound...
service. Number 468 differed from the rest of the class in that it had the 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 mounted on the firebox, with Urie N15
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...
style dome and safety valve casings, whilst the others had Drummond direct-loaded safety valves on their domes. As built, number 463 was fitted with a hooter rather than a whistle
Whistle
A whistle or call is a simple aerophone, an instrument which produces sound from a stream of forced air. It may be mouth-operated, or powered by air pressure, steam, or other means...
, which it kept until the Second World War. The class continued into British Railways service, though were gradually withdrawn in the early 1950s. This meant that none survived to be preserved.
LSWR and Southern
Under the LSWR, the D15s were outshopped in the LSWR Passenger Sage Green livery with purple-brown edging, creating panels of green. This was further lined in white and black with 'LSWR' in gilt on the tender tank sides. They were numbered 463–472 in a continuous block.When transferred to Southern Railway ownership after 1923, the locomotives carried Richard Maunsell's darker version of the LSWR livery. The LSWR standard gilt lettering was changed to yellow with 'Southern' on the water tank sides. The locomotives also featured black and white lining.