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GER Class L77

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GER Class L77
LNER Class N7
N7/1 on a suburban train for Brentwood, c.1927
Type and origin
Power typeSteam
DesignerA. J. Hill
Builder
Build date1915–1928
Total produced134
Specifications
Configuration:
​
 • Whyte0-6-2T
 • UICC1 h2t
Gauge4 ft 8+1⁄2 in (1,435 mm) standard gauge
Driver dia.4 ft 10 in (1.473 m)
Trailing dia.3 ft 9 in (1.143 m)
Wheelbase23 ft 0 in (7.01 m)
Length34 ft 10 in (10.62 m) over buffers
Axle load16 long tons 3 cwt (36,200 lb or 16.4 t)
Adhesive weight49 long tons 4 cwt (110,200 lb or 50 t)
Loco weight61.8–64.85 long tons (62.79–65.89 t)
Fuel typeCoal
Fuel capacity3 long tons 5 cwt (7,300 lb or 3.3 t)
Water cap.1,600 imperial gallons (7,270 L; 1,920 US gal)
Firebox:​
 • Grate area17.7 sq ft (1.64 m2)
Boiler pressure180 psi (1.24 MPa)
Heating surface1,291.7 sq ft (120.00 m2)
CylindersTwo, inside
Cylinder size18 in × 24 in (457 mm × 610 mm)
Valve gearWalschaerts
Performance figures
Tractive effort20,512 lbf (91.24 kN)
Factor of adh.5.37
Career
Operators
Class
  • GER: L77
  • LNER: N7
Power classBR: 3MT
Number in class
  • 1 January 1923: 12
  • 1 January 1948: 134
Axle load classLNER/BR: Route availability 5
Withdrawn1957–1962
DispositionOne preserved, remainder scrapped

The GER Class L77, LNER Class N7, is a class of 0-6-2T steam locomotives. They were designed by Alfred John Hill of the Great Eastern Railway and introduced in 1915. The design was perpetuated by Nigel Gresley of the LNER after the 1923 grouping. 134 were built and one example is preserved.

Overview

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The N7s had superheaters 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 and the East London Line but the condensing apparatus was removed between 1935 and 1938.

Numbering

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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 grouping. 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 added 60000 to their number (69600–69733).

Table of orders and numbers[1][2]
Year Order Manufacturer Quantity GER Nos. LNER Nos. 1946 Nos. Notes
1915 L77 Stratford Works 2 1000–1001 8000–8001 9600–9601 Renumbered 7978–7979 in 1944
1921 K85 Stratford Works 10 1002–1011 8002–8011 9602–9611 Renumbered 7980–7989 in 1944
1923–24 K89 Stratford Works 10 (990–999) 7990–7999 9612–9621
1925–26 — Gorton Works 30 — 409, 421, 426, 456, 457, 460, 464, 471, 473, 475, 826–830, 832–834, 837, 838, 850–853, 865–868, 870, 873 9622–9651 Class N7/1
1925–26 — Robert Stephenson & Co. 3897–3916 20 — 907, 912, 913, 916, 918, 919, 935, 940, 941, 947, 950, 952, 964, 966–968, 970, 971, 987, 988 9652–9671 Class N7/1
1927–28 — Gorton Works 10 — 2632–2641 9672–9681 Class N7/2
1927 — Wm. Beardmore & Co. 305–324 20 — 2642–2661 9682–9701 Class N7/2
1927–28 — Doncaster Works 1669–1692, 1696–1699, 1701/02/04/06 32 — 2600–2631 9702–9733 Class N7/3

Sub-classes

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N7/3 No. 69693 (with a round-top firebox) at St Margarets 4 April 1959
  • N7 Introduced 1914, GER Class L77 with Belpaire firebox
  • 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
Table of withdrawals[3]
Year Quantity in
service at
start of year		 Quantity
withdrawn		 Locomotive numbers Notes
1957 134 1 69689
1958 133 10 69601/06–09/24/28/41/43/95
1959 123 41 69600/02–05/10/12–13/16/19/22–23/25–27/33–35/37–39/44/49–50/55/57/59–62/66–67/69/72/76,
69703/05/11/16–17/31
1960 82 45 69611/14–15/17/20/29–30/36/42/45/47–48/52/54/63–65/77/80–85/87–88/91/94/99,
69700–01/04/06/09/12/15/18–22/26–27/29/33
1961 37 28 69618/31/51/56/58/68/70/73–75/78–79/86/90/93/96/98,
69702/07–08/10/13–14/23–24/28/30/32
1962 9 9 69621/32/40/46/53/71/92/97, 69725 69621 preserved

Accidents and incidents

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  • On 24 May 1954, locomotive No. 69638 ran into the turntable pit at Hatfield, Hertfordshire following the removal of the turntable.[4]

Preservation

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The preserved N7/4 No. 69621 (LNER 7999) at Dereham, Mid-Norfolk Railway, 2009

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. It was the last engine built by the Great Eastern Railway's Stratford Works[5] in 1924 and was preserved in 1962. It was also named in honour of its designer A J Hill in 1989.

References

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  1. ^ Aldrich 1969, p. 106
  2. ^ Boddy et al. 1977, pp. 121–3
  3. ^ Boddy et al. 1977, pp. 121–123.
  4. ^ Trevena 1981, p. 36.
  5. ^ Aldrich 1969, p. 148.

Sources

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  • Aldrich, C. Langley (1969). The Locomotives of the Great Eastern Railway 1862–1962 (7th ed.). Wickford, Essex: C. Langley Aldrich. OCLC 30278831.
  • Boddy, M. G.; Brown, W. A.; Fry, E. V.; Hennigan, W.; Hoole, Ken; Manners, F.; Neve, E.; Platt, E. N. T.; Proud, P.; Yeadon, W. B. (March 1977). Fry, E. V. (ed.). Locomotives of the L.N.E.R., Part 9A: Tank Engines—Classes L1 to N19. Kenilworth: RCTS. ISBN 0-901115-40-1.
  • Trevena, Arthur (1981). Trains in Trouble: Vol. 2. Redruth: Atlantic Books. ISBN 0-906899 03 6.
  • Ian Allan ABC of British Railways Locomotives, 1948 edition, part 4, pp 54–55
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Wikimedia Commons has media related to GER Class L77 / LNER Class N7.
External videos
video icon "Scrapping the Old Iron Horses", British Pathé; newsreel showing several LNER Class N7's being broken up
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