Diesel locomotives have seen limited use on the London Underground, largely because exhaust gases cannot be discharged when the vehicles are working in tunnels. A prototype diesel engine numbered DEL120 was built in 1939 from two 1915 stock motor cars, which was expected to be part of a batch of ten, but experience with
battery locomotives showed that these were a better alternative. Three 0-6-0 diesels (DL81-DL83) were obtained in 1971, to replace the last steam engines, but were too short to operate the signalling system, and too heavy for some of the bridges. In 1996, fourteen diesels (numbered 1 through 14, but also given female names) were supplied by
Schöma
Schöma is a company based in Diepholz, Germany, specialising in the construction of small diesel locomotives.
After Christoph Schöttler left his father's business, the :de:Diepholzer Maschinenfabrik Fritz Schöttler, Diepholzer Maschinenfabrik ...
of Germany, which were used during the construction of the
Jubilee line
The Jubilee line is a London Underground line that runs between in east London and in the suburban north-west, via the Docklands, South Bank and West End. Opened in 1979, it is the newest line on the Underground network, although some secti ...
tunnels. They were fitted with exhaust scrubbers, to enable them to work in the tunnels. To speed up track renewals on the subsurface lines,
Class 66 locomotives have been hired in since 2006 to handle permanent way trains, but again suffer from being too heavy for some of the bridges. Because they are not fitted with tripcock safety devices, and pull trains much longer than the signalling system is designed for, they are restricted to slow speed running.
DEL120
Design
The design of a prototype
diesel locomotive
A diesel locomotive is a type of railway locomotive in which the prime mover is a diesel engine. Several types of diesel locomotives have been developed, differing mainly in the means by which mechanical power is conveyed to the driving whee ...
which could work through London's tube tunnels was first considered in 1936, and work began on its construction at Acton Works in 1939. It was designed to use its
diesel engine
The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-call ...
when in the open air, but to draw current from the
third
Third or 3rd may refer to:
Numbers
* 3rd, the ordinal form of the cardinal number 3
* , a fraction of one third
* Second#Sexagesimal divisions of calendar time and day, 1⁄60 of a ''second'', or 1⁄3600 of a ''minute''
Places
* 3rd Street (d ...
and
fourth rail
A railway electrification system supplies electric power to railway trains and trams without an on-board prime mover or local fuel supply.
Electric railways use either electric locomotives (hauling passengers or freight in separate cars), ele ...
when underground. Two
Brush
A brush is a common tool with bristles, wire or other filaments. It generally consists of a handle or block to which filaments are affixed in either a parallel or perpendicular orientation, depending on the way the brush is to be gripped durin ...
built
1915 Stock (also known as 'Ealing Stock') driving motors, numbered 3937 and 3941, which had been withdrawn from the Central London line, were converted into the
electro-diesel locomotive
An electro-diesel locomotive (also referred to as a dual-mode or bi-mode locomotive) is a type of locomotive that can be powered either from an electricity supply (like an electric locomotive) or by using the onboard diesel engine (like a diese ...
. The work involved scrapping the passenger saloons and joining the two driving ends together to form a double ended locomotive. The central bay held a
six-cylinder
The straight-six engine (also referred to as an inline-six engine; abbreviated I6 or L6) is a piston engine with six cylinders arranged in a straight line along the crankshaft. A straight-six engine has perfect primary and secondary engine balan ...
two-stroke diesel engine
A two-stroke diesel engine is an internal combustion engine that uses compression ignition, with a two-stroke combustion cycle. It was invented by Hugo Güldner in 1899.Mau (1984) p.7
In compression ignition, air is first compressed and heated; ...
, manufactured by
Petters, which was coupled to a
direct current
Direct current (DC) is one-directional flow of electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor such as a wire, but can also flow through semiconductors, insulators, or even ...
generator
Generator may refer to:
* Signal generator, electronic devices that generate repeating or non-repeating electronic signals
* Electric generator, a device that converts mechanical energy to electrical energy.
* Generator (circuit theory), an eleme ...
.
Construction
The prototype, which was the first electro-diesel locomotive to be constructed in Britain, was completed in November 1940, and was painted in Metropolitan 'Lake', with gold lining. It was intended to build ten similar locomotives, to replace the fleet of steam engines, and a further 18 withdrawn motor cars were stored at Cockfosters depot with this in mind. The construction of further locomotives was delayed by the outbreak of the
Second World War
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
, and experience with the 1935 fleet of
battery locomotives showed that these were a better solution.
[
]
Service
DEL120 entered normal service in 1941, but was not a success, as the complicated operating system resulted in frequent breakdowns and repairs. It was used initially around Watford, and was transferred to Hainault to work ballast trains after an overhaul in 1952. It was moved to Golders Green depot temporarily, to operate a works train while an experimental ground wheel lathe was installed. The diesel engine was removed in 1954, after which it was only used for shunting, initially at Hainault and later at Acton. It was not ideal as a shunting engine, as visibility from the cab was poor, and access difficult, and so it was idle from 1956, finally being scrapped in 1958.[
]
DL81-DL83
Three Rolls-Royce-engined diesel-hydraulic locomotives were built in 1967–68, and were supplied to an open-cast iron ore mine at Corby
Corby is a town in North Northamptonshire, England, located north-east of Northampton. From 1974 to 2021, the town served as the administrative headquarters of the Borough of Corby. At the 2011 Census, the built-up area had a population of 5 ...
. When the iron ore was worked out, the locomotives were surplus to requirements, and were acquired by London Transport in 1971. They were numbered in the range DL81-DL83. All three were standard 0-6-0DH Sentinel diesel shunters obtained from Thomas Hill (Rotherham) Ltd
Thomas Hill (Rotherham) Limited was a company which repaired and sold steam road vehicles, diesel and electric road vehicles and railway locomotives. It later made its name building and rebuilding diesel locomotives.
History
The Company was fo ...
(the Rolls Royce/Sentinel dealer). They were painted dark green and operated at Neasden and Lillie Bridge
The Lillie Bridge Grounds was a sports ground on the Fulham side of West Brompton, London. It opened in 1866, coinciding with the opening of West Brompton station. It was named after the local landowner, Sir John Scott Lillie (1790–1868) and ...
depots where they replaced the last of the ex-GWR pannier tank steam locomotives.
The locomotives had a wheelbase of only , and this was too short to operate the track circuits. Since this made their use impracticable, each was permanently coupled to a tender, which consisted of a bogie removed from a redundant District line
The District line is a London Underground line running from in the east and Edgware Road in the west to in west London, where it splits into multiple branches. One branch runs to in south-west London and a short branch, with a limited servic ...
Q Stock car. The weight of the bogie was increased to 17 tons, and it was fitted with tripcocks and sleet brushes, so that it could be used for clearing snow and ice from the current rails. Although the tenders were permanently coupled to the locomotives, they carried separate numbers, and were identified as DT81, DT82 and DT83. The tender increased the wheelbase to .[
One locomotive was normally operational at each of the depots, with the third kept as a spare. Transfers between the works occurred when maintenance or repairs were necessary. Movement outside of the depots was severely restricted when the civil engineering department decided that the short wheelbase and 16-ton axle loading might cause overloading problems on a number of bridges.][ Both the free end (front) of the locomotive and the tender were fitted with 'Ward' type couplers as well as normal buffers and couplings to allow them the couple to almost any Departmental rolling stock (at the time).
The locomotives had all been withdrawn from service by March 1993, as engineers trains were no longer operated from Neasden Depot. Two locomotives were subsequently preserved; no. DL82 on the ]Mid-Norfolk Railway
The Mid-Norfolk Railway (MNR) is a preserved standard gauge heritage railway, one of the longest in Great Britain. Preservation efforts began in 1974, but the line re-opened to passengers only in the mid-1990s as part of the "new generation" o ...
and no. DL83 on the Nene Valley Railway
The Nene Valley Railway (NVR) is a preserved railway in Cambridgeshire, England, running between Peterborough Nene Valley and Yarwell Junction. The line is in length. There are stations at each terminus, and three stops en route: Orton Mere, ...
. The third locomotive, no. DL81, was sold for further use with an industrial user.
Schöma
In connection with the construction of the Jubilee Line Extension
The Jubilee Line Extension (JLE) is the extension of the London Underground Jubilee line from to through south and east London. An eastward extension of the line was first proposed in the 1970s. As part of the development of London Docklands, ...
project, fourteen diesel-hydraulic locomotives were purchased from Schöma
Schöma is a company based in Diepholz, Germany, specialising in the construction of small diesel locomotives.
After Christoph Schöttler left his father's business, the :de:Diepholzer Maschinenfabrik Fritz Schöttler, Diepholzer Maschinenfabrik ...
of Germany to assist in equipping the tunnels prior to electrification. Weighing 33.88 tonnes each, they are long, and are powered by six-cylinder inline diesel engines, which give them a maximum speed of . They entered service from February 1996, are built to tube tunnel loading gauge, and were fitted with buckeye couplers when built. They are equipped with exhaust scrubbers to prevent soot and other particles from being expelled into the tunnels. The locomotives have since been used on other engineering projects. When not in use they can be found at Lillie Bridge Depot
Lillie Bridge Depot is a historic English traction maintenance depot on the London Underground Piccadilly and District lines, situated between West Brompton and West Kensington stations in the London Borough of Hammersmith and Fulham. It is acce ...
or Ruislip depot.
Following the completion of the Jubilee Line extension, ownership of the vehicles was transferred to London Underground Transplant. Numbers 1 and 5 have been modified by fitting Wedgelock couplers so that they can be used to shunt tube stock, whilst numbers 3 and 6 have been fitted with emergency couplers.
Leased locomotives
Class 66
Metronet contracted five newly built Class 66 locomotives from GB Railfreight
GB Railfreight (GBRf) is a rail freight company in the United Kingdom. As of 2022, it is owned by the global investment company Infracapital.
GB Railfreight was established in April 1999 as the rail freight operating subsidiary of the train o ...
in order to speed up track replacement works on the London Underground network. They were first used in August 2006, pulling engineering trains consisting of wagons and high-output track laying equipment nearly long. The locomotives are capable of hauling consists with a maximum length of , thus reducing from 30 to 8 the number of trains needed to supply materials to relay a typical weekend possession of track, and as a consequence increasing the amount of track that can be renewed. One disadvantage of the heavier locomotives is that bridges on the District line
The District line is a London Underground line running from in the east and Edgware Road in the west to in west London, where it splits into multiple branches. One branch runs to in south-west London and a short branch, with a limited servic ...
needed to be strengthened to carry the extra weight. While working on the network, they are restricted to a maximum speed of , since they are not fitted with tripcocks, and the signalling infrastructure is only designed to cope with trains having a maximum length of .
Sources
*
*
*
References
{{London Underground Rolling Stock
Diesel locomotives of Great Britain
Diesel
Diesel may refer to:
* Diesel engine, an internal combustion engine where ignition is caused by compression
* Diesel fuel, a liquid fuel used in diesel engines
* Diesel locomotive, a railway locomotive in which the prime mover is a diesel engin ...
Standard gauge locomotives of Great Britain