LNER Thompson Class L1

LNER Thompson Class L1
No. 67781 at Neasden Shed 1957
Type and origin Power type Steam Designer Edward Thompson Builder Doncaster Works (1) Darlington Works (29) North British Locomotive Co. (35) Robert Stephenson and Hawthorns (35) Build date 1945, 1948–1950 Total produced 100
Specifications Configuration: ​  • Whyte 2-6-4T  • UIC 1′C2′ h2t Gauge 4 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) Length 43 ft 4 in (13.21 m) Axle load 20.00 long tons (20.32 t) Adhesive weight 58.95 long tons (59.90 t) Loco weight 89.45 long tons (90.89 t) Fuel type Coal Fuel capacity 4.50 long tons (4.57 t) Water cap. 2,630 imp gal (12,000 L; 3,160 US gal) Firebox: ​  • Grate area 24.75 sq ft (2.299 m2) Boiler LNER diagram 115 Boiler pressure 225 lbf/in2 (1.55 MPa) Heating surface: ​  • Firebox 138.5 sq ft (12.87 m2)  • Tubes 830.0 sq ft (77.11 m2)  • Flues 368.0 sq ft (34.19 m2)  • Total surface 1,336.5 sq ft (124.16 m2) Superheater: ​  • Heating area 284.0 sq ft (26.38 m2) Cylinders Two, outside Cylinder size 20 in × 26 in (508 mm × 660 mm) Valve gear Walschaerts Valve type 10-inch (254 mm) piston valves
Performance figures Tractive effort 32,080 lbf (142.70 kN)
Career Operators London and North Eastern Railway British Railways Class L1 Power class BR: 4MT Numbers BR: 67701–67800 Axle load class Route Availability 7 Withdrawn 1960–1962 Disposition All scrapped

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.

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.

Modifications

In an attempt to reduce wear, two experiments were tried. 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

Sources were used to compile the following table:

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.

Modelling

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

References

• Template:RCTS-LocosLNER-9A