The GER Class L77, LNER Class N7, is a class of

0-6-2T T, or t, is the twentieth letter in the modern English alphabet and the ISO basic Latin alphabet. Its name in English is ''tee'' (pronounced ), plural ''tees''. It is derived from the Semitic letters taw (ת, ܬ, ت) via the Greek letter ...

steam locomotives A steam locomotive is a locomotive that provides the force to move itself and other vehicles by means of the expansion of steam. It is fuelled by burning combustible material (usually coal, oil or, rarely, wood) to heat water in the locomot ...

. They were designed by

Alfred John Hill Alfred John Hill (1 January 1862–1 January 1927) was Chief Mechanical Engineer at the Stratford Works of the Great Eastern Railway from 1912 to 1922. His best-known design is probably the GER Class L77 0-6-2 tank locomotive which was perpetua ...

of the

Great Eastern Railway The Great Eastern Railway (GER) was a pre-grouping British railway company, whose main line linked London Liverpool Street to Norwich and which had other lines through East Anglia. The company was grouped into the London and North Eastern Ra ...

and introduced in 1915. The design was perpetuated by

Nigel Gresley Sir Herbert Nigel Gresley (19 June 1876 – 5 April 1941) was a British railway engineer. He was one of Britain's most famous steam locomotive engineers, who rose to become Chief Mechanical Engineer (CME) of the London and North Eastern Rail ...

of the LNER after the 1923

grouping Grouping may refer to: * Muenchian grouping * Principles of grouping * Railways Act 1921, also known as Grouping Act, a reorganisation of the British railway system * Grouping (firearms), the pattern of multiple shots from a sidearm See also ...

. 134 were built and one example is preserved.

Overview

The N7s had

superheater A superheater is a device used to convert saturated steam or wet steam into superheated steam or dry steam. Superheated steam is used in steam turbines for electricity generation, steam engines, and in processes such as steam reforming. There ...

s and piston valves. They were unusual (for inside-cylinder locomotives) in having Walschaerts valve gear. They were, as London suburban locomotives, fitted with Westinghouse air brakes. Some were fitted with condensing apparatus for working on the

Metropolitan line The Metropolitan line, colloquially known as the Met, is a London Underground line between in the City of London and and in Buckinghamshire, with branches to in Hertfordshire and in Hillingdon. Printed in magenta on the tube map, the lin ...

and the East London Line but the condensing apparatus was removed between 1935 and 1938.

Numbering

The first 22 were allocated numbers in the 990–1011 range when ordered by the GER, but the last 10 did not emerge until the

. The LNER added 7000 to their GER numbers, and then built a further 112 locomotives between 1925 and 1928. In the 1946 renumbering scheme, they were renumbered 9600–9733, and upon nationalisation in 1948,

British Railways British Railways (BR), which from 1965 traded as British Rail, was a state-owned company that operated most of the overground rail transport in Great Britain from 1948 to 1997. It was formed from the nationalisation of the Big Four British ...

added 60000 to their number (69600–69733).

Sub-classes

St Margarets station with Liverpool Street train geograph-2886847-by-Ben-Brooksbank

* N7 Introduced 1914, GER Class L77 with

Belpaire firebox The Belpaire firebox is a type of firebox used on steam locomotives. It was invented by Alfred Belpaire of Belgium in 1864. Today it generally refers to the shape of the outer shell of the firebox which is approximately flat at the top and s ...

* N7/1 Introduced 1925, LNER development of GER design with Belpaire firebox * N7/2 Introduced 1926, LNER locos with Belpaire firebox and long-travel valves * N7/3 Introduced 1927, LNER locos with round-top firebox, plus from 1943, rebuilds of N7/2 with round-top firebox * N7/4 Introduced 1940, GER locos rebuilt with round-top firebox * N7/5 Introduced 1943, N7/1 locos rebuilt with round-top firebox

Accidents and incidents

*On 24 May 1954, locomotive No. 69638 ran into the turntable pit at

Hatfield, Hertfordshire Hatfield is a town and civil parish in Hertfordshire, England, in the borough of Welwyn Hatfield. It had a population of 29,616 in 2001, and 39,201 at the 2011 Census. The settlement is of Saxon origin. Hatfield House, home of the Marquess o ...

following the removal of the turntable.

Preservation

One LNER example, No. 7999 (BR No. 69621) has been preserved and is currently on static display pending overhaul at the East Anglian Railway Museum at Chappel & Wakes Colne. It is owned by the

East Anglian Railway Museum The East Anglian Railway Museum is located at Chappel and Wakes Colne railway station in Essex, England, which is situated on the former Great Eastern Railway branch line from Marks Tey to Sudbury. Services on the Sudbury Branch Line are op ...

. It was the last engine built by the Great Eastern Railway's Stratford Works in 1924 and was preserved in 1962. It was also named in honour of its designer A J Hill in 1989.

References

Sources

* * * * Ian Allan ABC of British Railways Locomotives, 1948 edition, part 4, pp 54–55