LNER Thompson Class L1

The London and North Eastern Railway (LNER) Thompson Class L1 was a class of 2-6-4T steam locomotives designed by Edward Thompson. The prototype no. 9000 was built in 1945, but the remaining 99 were built under British Railways jurisdiction in the period 1948–1950.

LNER Thompson Class L1[1]
No. 67781 at Neasden Shed 1957
Type and origin
Power typeSteam
DesignerEdward Thompson
Builder
Build date1945, 1948–1950
Total produced100
Specifications
Configuration:
​
 • Whyte2-6-4T
 • UIC1′C2′ h2t
Gauge4 ft 8 1⁄2 in (1,435 mm)
Leading dia.3 ft 2 in (0.965 m)
Driver dia.5 ft 2 in (1.575 m)
Trailing dia.3 ft 2 in (0.965 m)
Length43 ft 4 in (13.21 m)
Axle load20.00 long tons (20.32 t)
Adhesive weight58.95 long tons (59.90 t)
Loco weight89.45 long tons (90.89 t)
Fuel typeCoal
Fuel capacity4.50 long tons (4.57 t)
Water cap2,630 imp gal (12,000 l; 3,160 US gal)
Firebox:
 • Firegrate area		24.75 sq ft (2.299 m2)
BoilerLNER diagram 115
Boiler pressure225 lbf/in2 (1.55 MPa), 200 lbf/in2 (1.38 MPa)
Heating surface1,336.5 sq ft (124.16 m2)
 • Tubes830.0 sq ft (77.11 m2)
 • Flues368.0 sq ft (34.19 m2)
 • Firebox138.5 sq ft (12.87 m2)
Superheater:
​
 • Heating area284.0 sq ft (26.38 m2)
CylindersTwo, outside
Cylinder size20 in × 26 in (508 mm × 660 mm), 18.75 in × 26 in (476 mm × 660 mm) on some engines
Valve type10-inch (254 mm) piston valves
Performance figures
Tractive effort32,080 lbf (142.70 kN) on most engines, between 25,063 lbf (111.49 kN) and 28,516 lbf (126.85 kN) on some engines experimentally
Career
Operators
ClassL1
Power classBR: 4MT
NumbersBR: 67701–67800
Axle load classRoute Availability 7
Locale
Withdrawn1960–1962
DispositionAll scrapped

Overview

The class, at least on paper, should have been very free steaming and powerful engines but, in practice, they were not suited to the work to which they were assigned. The engines had 5-foot-2-inch (1.575 m) driving wheels, which would give them excellent power at low speed, such as that required for freight work, but these engines were intended for passenger use. The speeds required for suburban passenger work wore the engines out in a remarkably short time. Axleboxes, crosshead slides and crank bearings all suffered due to the high speeds.

Accidents and incidents
  • On 19 November 1958, a freight train overran signals and was in a rear-end collision with another at Hitchin, Hertfordshire. A third freight train ran into the wreckage and was derailed. Locomotive No. 67785 was pushed over by the wagons from the third train.[2]

Modifications

In an attempt to reduce wear, two experiments were tried.[3] In May 1951, five locomotives had liners fitted to their cylinders to reduce the cylinder bore from 20 to 18 3⁄4 in (508 to 476 mm). In March 1953, five locomotives had their boiler pressure reduced from 225 to 200 lbf/in2 (1.55 to 1.38 MPa). Neither experiment was a success.

Numbering
Class numbering details[3][4][5]
Build date Builder Serial number LNER number Original BR number New BR number
1945 LNER Doncaster Works 1984 9000 69000 67701
1948 BR Darlington Works 2020–2034 9001–9003, E9004–E9012 69001-69015 67702-67716
1948 BR Darlington Works 2035–2048 — – 67717-67730
1948–1949 North British Locomotive Company 26570–26604 — — 67731-67765
1949–1950 Robert Stephenson and Hawthorns 7500–7534 — — 67766-67800

Withdrawal

Withdrawals were between 1960 and 1962. None survived to preservation.

YearQuantity in
service at
start of year		Quantity
withdrawn		Locomotive numbersNotes
19601001267701–02/04–06/08–09/11/14/25–26/36
1961882467707/12–13/17–19/22/28/32/38–40/48/50/58/60/62/68–69/72/75/82/90/94
1962646467700/03/10/15–16/20–21/23–24/27/29–31/33–35/37/41–47/49/51–57/59/61/63–67/70–71/73–74/76–81/83–89/91–93/95–800

Modelling

Hornby produces the L1 class in 00 gauge with a number of different liveries, both green with LNER or BR running numbers,[6][7] and black with BR running numbers.[8][9]

References
  1. Boddy et al. 1977, p. 16, 29–31.
  2. Trevena, Arthur (1981). Trains in Trouble: Vol. 2. Redruth: Atlantic Books. pp. 40–41. ISBN 0-906899-03-6.
  3. "The Thompson L1 2-6-4T Tank Locomotives". LNER Encyclopedia.
  4. "Class Details". RailUK.
  5. Boddy et al. 1977, p. 16.
  6. "(404)". Hornby. Archived from the original on 19 November 2010.
  7. "(404)". Hornby. Archived from the original on 20 July 2011.
  8. "(404)". Hornby. Archived from the original on 20 July 2011.
  9. "National Model Rail Database". National Model Rail. Archived from the original on 4 March 2016. Retrieved 13 September 2015.
  • 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.
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