SECR K and SR K1 Classes

SECR K And SR K1 Classes

The SECR K class was a type of 2-6-4 tank locomotive designed in 1914 by Richard Maunsell for express passenger duties on the South Eastern and Chatham Railway (SECR). The Southern Railway (SR) K1 class was a three-cylinder variant of the K class, designed in 1925 to suit a narrower loading gauge. They were among the first non-Great Western Railway (GWR) types to use and improve upon the basic design principles of power and standardisation established by GWR Chief Mechanical Engineer (CME) George Jackson Churchward. The locomotives were based on the GWR 4300 class, improved by the Midland Railway's ideals of simplicity and ease of maintenance.

The K class was designed to be mechanically similar to the SECR N class 2-6-0 mixed-traffic locomotives. The class was the earliest large-scale use of the 2-6-4 wheel arrangement in Britain. Production began towards the end of the First World War, and the prototype rolled out of Ashford Works three years after design work was completed due to wartime production constraints. The class replaced obsolete 4-4-0 passenger locomotives in an SECR fleet standardisation programme.

Twenty-one locomotives were built: twenty K class (two cylinders) and one K1 class (three cylinders), the first in 1917 and the remainder between 1925 and 1926. They operated over the Eastern section of the Southern Railway network and were given the names of rivers, being referred as the River class from 1925. Crews referred to the K and K1 classes as "Rolling Rivers" because of their instability when travelling at speed. They were rebuilt as 2-cylinder SR U class and 3-cylinder SR U1 class 2-6-0s (respectively) following a railway accident at Sevenoaks, Kent in 1927. They continued in service with British Railways (BR) until the last was withdrawn in 1966. One K class rebuild (No. 1806) is preserved on the Watercress Line in Hampshire and as of 2011 is operational.