LNER Thompson Class A1/1

LNER Thompson Class A1/1
The single Thompson A1/1 Pacific 60113 Great Northern near Peterborough in 1959
Type and origin Power type Steam Designer Edward Thompson Build date 1922 Rebuilder Doncaster Works Rebuild date 1945 Number rebuilt 1
Specifications Configuration: ​  • Whyte 4-6-2  • UIC 2'C1' h3 Gauge 4 ft 8+1⁄2 in (1,435 mm) Leading dia. 3 ft 2 in (0.965 m) Coupled dia. 6 ft 8 in (2.032 m) Trailing dia. 3 ft 8 in (1.118 m) Wheelbase 63 ft 6.625 in (19.37 m) ​  • Engine 38 ft 5 in (11.71 m)  • Coupled 14 ft 6 in (4.42 m) Length 73 ft 2 in (22.301 m) Loco weight 101.5 long tons (103.1 t; 113.7 short tons) Tender weight 60.7 long tons (61.7 t; 68.0 short tons) Total weight 159.5 long tons (162.1 t; 178.6 short tons) Fuel capacity 9 long tons (9.144 t) Water cap. 5,000 imp gal (22,730.45 L; 6,004.75 US gal) Firebox: ​  • Grate area 41.5 sq ft (3.86 m2) Boiler 6 ft 5 in (1.96 m) max diameter Boiler pressure 250 psi (1.72 MPa) Heating surface: ​  • Firebox 231.2 sq ft (21.48 m2)  • Tubes 1,281.4 sq ft (119.05 m2)  • Flues 1,063.7 sq ft (98.82 m2)  • Total surface 2,576.3 sq ft (239.35 m2) Superheater: ​  • Heating area 748.9 sq ft (69.58 m2) Cylinders Three Cylinder size 19 in × 26 in (483 mm × 660 mm) Valve gear Walschaerts Valve type Piston valves
Performance figures Tractive effort 37,400 lbf (166.36 kN)
Career Operators London and North Eastern Railway British Railways Class LNER: A1/1 Power class BR: 8P6F Numbers 4470/113/60113 Retired 1962 Disposition Scrapped

The LNER Class A1/1 consisted of a single 4-6-2 "Pacific" express passenger locomotive rebuilt in 1945 from an A1 class locomotive, by Edward Thompson. It was intended as the prototype of a new design of pacific locomotives improving the A4 design of Thompson's predecessor Sir Nigel Gresley. No further examples were built due to Thompson's retirement in 1946.