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SECR J class
J class 1598 at Ashford 1946
Type and origin Power type Steam Designer Harry Wainwright Builder Ashford Works Build date 1913 Total produced 5
Specifications Configuration: ​  • Whyte 0-6-4T  • UIC C2′ h2t Gauge 4 ft 8+1⁄2 in (1,435 mm) Driver dia. 5 ft 6 in (1.676 m) Trailing dia. 3 ft 7 in (1.092 m) Axle load 18 long tons 14 cwt (41,900 lb or 19 t) Adhesive weight 51 long tons 18 cwt (116,300 lb or 52.7 t) Loco weight 70 long tons 14 cwt (158,400 lb or 71.8 t) Fuel type Coal Fuel capacity 3 long tons 5 cwt (7,300 lb or 3.3 t) Water cap. 2,000 imp gal (9,100 L; 2,400 US gal) Firebox: ​  • Grate area 17.6 sq ft (1.64 m2) Boiler pressure 160 lbf/in2 (1.10 MPa) Heating surface: ​  • Firebox 112 sq ft (10.4 m2)  • Tubes 593 sq ft (55.1 m2)  • Flues 294 sq ft (27.3 m2) Superheater: ​  • Type Schmidt  • Heating area 234 sq ft (21.7 m2) Cylinders Two, inside Cylinder size 19+1⁄2 in × 26 in (495 mm × 660 mm) Valve type 8-inch (203 mm) piston valves
Performance figures Tractive effort 20,400 lbf (90.74 kN)
Career Operators South Eastern and Chatham Railway → Southern Railway → Southern Region of British Railways Class SECR / SR: J Withdrawn 1949–1951 Disposition All scrapped

The SECR J class was a class of 0-6-4T steam tank locomotive built for heavy freight service on the South Eastern and Chatham Railway, by Harry Wainwright.

The South Eastern and Chatham Railway (SECR) had a need for versatile mixed traffic locomotives which could accelerate quickly so as not to impede the heavy passenger traffic on the densely used lines around London. Following the success of his C class 0-6-0 and his H class 0-4-4T Harry Wainwright sought to combine their good features but was limited by weight restrictions on many lines. The result was an 0-6-4 tank.^[1] Five locomotives were constructed at Ashford during 1913, but Wainwright retired soon afterwards and no more were constructed. The class were moderately successful on a variety of secondary passenger and freight services. All had completed more than one million miles at the time of their withdrawal between 1949 and 1951.^[2][3]

The class were originally allocated unused numbers between 126 and 614. However, all but number 597 were renumbered by the Southern Railway in 1927/8 to create a unified sequence from A596 to A599. These later became 1596–1599, and then 31596–31599 under British Railways.

• "SECR J Class 0-6-4T". Southern E-Group.
• "Class J Details". RailUK.