GER Class L77

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GER Class L77
LNER Class N7
300px
N7/1 on a suburban train for Brentwood, c.1927
Type and origin
Power type Steam
Designer A. J. Hill
Builder
Build date 1915–1928
Total produced 134
Specifications
Configuration 0-6-2T
UIC class C1 h2t
Gauge 4 ft 8 1⁄2 in (1,435 mm) standard gauge
Driver diameter 4 ft 10 in (1.473 m)
Trailing dia 3 ft 9 in (1.143 m)
Wheelbase 23 ft 0 in (7.01 m)
Length 34 ft 10 in (10.62 m) over buffers
Adhesive weight 49 long tons 4 cwt (110,200 lb or 50 t)
Loco weight 61.8–64.85 long tons (62.79–65.89 t)
Fuel type Coal
Fuel capacity 3 long tons 5 cwt (7,300 lb or 3.3 t)
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Boiler pressure 180 psi (1.24 MPa)
Firegrate area 17.7 sq ft (1.64 m2)
Heating surface 1,291.7 sq ft (120.00 m2)
Cylinders Two, inside
Cylinder size 18 in × 24 in (457 mm × 610 mm)
Valve gear Walschaerts
Performance figures
Tractive effort 20,512 lbf (91.24 kN)
Career
Operators
Class
  • GER: L77
  • LNER: N7
Power class BR: 3MT
Number in class
  • 1 January 1923: 12
  • 1 January 1948: 134
Axle load class LNER/BR: Route availability 5
Withdrawn 1957–1962
Disposition One 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; only one of them is preserved.

Overview

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

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

File:St Margarets station with Liverpool Street train geograph-2886847-by-Ben-Brooksbank.jpg
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,
69700/01/04/06/09/12/15/18/18–22/26/27/29/33
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

Preservation

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

One, 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[4] in 1924 and was preserved in 1962. It was also named in honour of its designer A J Hill in 1989.

References

  1. ↑ Aldrich 1969, p. 106
  2. ↑ Boddy et al. 1977, pp. 121–3
  3. ↑ Boddy et al. 1977, pp. 121–123.
  4. ↑ Aldrich 1969, p. 148.

Sources

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

External links

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