GNR 521 Class

The Great Northern Railway 521 Class was a class of 0-6-0 steam locomotives, introduced in 1911. They were designed by Henry Ivatt for goods traffic. From 1912 to 1922 further examples, slightly modified by Nigel Gresley, were built and designated 536 Class. The most obvious difference was in the front sandboxes. These were below the running plate on the 521 but above it, and merged with the front splashers, on the 536. The boiler and firebox were also moved back, thus resulting in a shortened cab. The London and North Eastern Railway classified them both as J6. These locomotives had superheaters and piston valves operated by Stephenson valve gear. The class earned the nickname "Knick-Knacks" due to the sound made by the locomotives when steam was shut off.

GNR 521 Class and 536 Class (J22) LNER Class J6
Gresley J6 No. 4199 at Grantham 1947
Type and origin Power type Steam Designer Henry Ivatt and Nigel Gresley Builder Doncaster Works Build date August 1911-September 1922 Total produced 110
Specifications Configuration: ​  • Whyte 0-6-0  • UIC C h2 Gauge 4 ft 8+1⁄2 in (1,435 mm) standard gauge Driver dia. 5 ft 2 in (1,575 mm) Tender wheels 4 ft 2 in (1,270 mm) Wheelbase 38 ft 10 in (11.84 m)  • Engine 16 ft 3 in (4.95 m)  • Tender 13 ft (4.0 m) Length 52 ft 6 in (16,002.00 mm) Axle load 18 long tons (20.16 short tons) Loco weight 50 long tons 10 cwt (113,100 lb or 51.3 t) Tender weight 43 long tons 2 cwt (96,500 lb or 43.8 t) Fuel type Coal Fuel capacity 6 long tons 10 cwt (14,600 lb or 6.6 t) Water cap. 3,500 imp gal (16,000 l; 4,200 US gal) Boiler pressure 170 lbf/in2 (1.17 MPa) Cylinders Two, inside Cylinder size 19 in × 26 in (483 mm × 660 mm) Valve gear Stephenson Valve type piston valves
Performance figures Tractive effort 21,875 lbf (97.30 kN)
Career Operators Great Northern Railway → London and North Eastern Railway → British Railways Class GN: 521 class and 536 class → GN: J22 → LNER: J6 Power class BR: 2P3F Numbers GN: 521–610, 621–640 LNER (1923): 3521-3610, 3621-3640 LNER (1946): 4170-4279 BR: 64170-64279 Nicknames "Knick-Knacks" Withdrawn 1955-1962 Disposition All scrapped