LNWR Class B
No. 1881 (later LMS 8900) in photographic grey livery - classified B from 1911
Type and origin Power type Steam Designer Francis Webb Builder Crewe Works Build date 1901-1904 Total produced 170
Specifications Configuration: ​  • Whyte 0-8-0  • UIC D n4v Gauge 4 ft 8+1⁄2 in (1,435 mm) Driver dia. 4 ft 5+1⁄2 in (1.359 m) Loco weight 53 long tons 10 cwt (119,800 lb or 54.4 t) Fuel type coal Boiler pressure 200 psi (1.38 MPa) Cylinders 4, compound High-pressure cylinder (2 outside) 15" x 24" Low-pressure cylinder (2 inside) 20+1⁄2" x 24"
Career Operators LNWR » LMS Disposition 26 rebuilt to Class E 1904–08 10 rebuilt to Class F 1906–08 32 rebuilt to Class G 1906–17 91 rebuilt to Class G1 1917–27 11 scrapped 1921–28

The London and North Western Railway (LNWR) Class B was a class of 0-8-0 steam locomotives introduced in 1901.^[1] A development of the three-cylinder compound Class A (though this letter classification was not introduced until 1911), they had a 4-cylinder compound arrangement. 170 were built between 1901 and 1904.

Rebuilds

Class E

Between 1904 and 1908, Webb's successor George Whale added a leading pony truck to 26 engines, making them 2-8-0s and taking them into Class E (again from 1911).

Class F

Between 1906 and 1908, Whale also rebuilt 10 with larger Experiment-type boiler to Class F, again adding a leading pony truck. (Two more of Class B were also converted to Class F via Class E).

Class G

Neither of the above conversions was particularly successful and, as a result, 32 were rebuilt to Class G with 2-cylinder simple expansion between 1910 and 1917.

Class G1

Whale's Successor Charles Bowen Cooke rebuilt a further 91 direct from Class B to 2-cylinder simple superheated LNWR Class G1 (also known as "Super Ds"). The rebuilds from Class B to Class G1 continued under LMS ownership between 1923 and 1927.

Summary

A total of 170 locomotives was built but No. 134 was destroyed in a boiler explosion at Buxton on 11 November 1921 leaving 169. The rebuilds (some under LMS ownership) totalled 159, leaving 10 unrebuilt.

LMS ownership

The London, Midland and Scottish Railway (LMS) inherited 53 unrebuilt Class B locomotives in 1923 and numbered them 8900–8952. The LMS continued to rebuild them to Class G1 and the number of unrebuilt locomotives dwindled to 10.

Withdrawal

The remaining 10 Class B locomotives were withdrawn in 1927–1928. None were preserved.