South Eastern & Chatham 2-6-4 Locomotives in Great_Britain

Class Details by Steve Llanso of Sweat House Media

Class K (Locobase 2357)

See "New Locomotives: South East and Chatham Ry", Locomotive Magazine, Volume XXIII [23], No Volume 302 (15 October 1917); 15 November 1917, p. 219; and 15 December 1917, pp. 240-241. See also Ahrons (1927) for data; "Maunsell K/K1 class 2-6-4T" from the Southern Railway E-Group website at [], last accessed 17 September 2018; and and "New Standard Boilers and Cylinders for South East & Chatham Railway Locomotives", Railway Engineer, Volume 41, No 8 (August 1920), pp. 342. Prototype built at Ashford in 1917, production variants manufactured by Armstrong Whitworth in 1925. K1s manufactured at Ashford in 1925 (A890) and 1926 (A800-A809).

REL Maunsell's elaboration of the Baltic wheel arrangement as tank engine and, incidentally, of the Belpaire firebox and coned boiler of his concurrently built Moguls (Locobase 2341, which see for details on the boiler). Note the relatively high drivers. They used 10" (254 mm) piston valves to supply steam to the cylinders.

A form of feed-water heating used external pipes from the tanks that let in the water on either side of the dome. The water then flowed, read the LM report, "in a shallow stream over a helical tray to a saddle upon the steam pipe whence it falls into the boiler." Lengthening the path the water traveled meant the cold water was "exposed to the steam sufficiently long to be raised to a high temperature before touching the boiler plates and tubes." In addition to the lesser amount of sudden cooling, the system allowed salts entrained in the water and to settle at the bottom of the boiler barrel.

The front-end regulator was housed in the smokebox as was the Maunsell/Hutchinson header that topped a Schmidt-type superheater.

The leading bogie was a Cartazzi-type with a spherical central pivot and inclined planes for centering; these latter were encased in an oil bath.

The first of the class, River Avon, was a loner until nine were produced by Armstrong Withworth in 1925, followed by ten more K1s from Brighton in 1926. The Southern Railways E-Group account argues that the these "River" class engines were "generally successful" But, the history continues, "some crews, particularly on the Central Section, complained that they would roll heavily and unpredictably when at speed on indifferent track". Several of the class suffered serious derailments in 1923 and 1927, the 25 August 1927 Sevenoaks derailment contributing to the decision to convert the Ks into 2-6-0 tender engines in 1928. This modification, says the E-Group, "probably rather unfair to the 2-6-4T design as it is almost certain that the major cause of the accident was the poor state of the track rather than the locomotive design."

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID2357
RailroadSouth Eastern & Chatham
CountryGreat Britain
Number in Class20
Road Numbers790, A791-A799, A890, A800-A809
Number Built20
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)15 / 4.57
Engine Wheelbase (ft / m)35.83 / 10.92
Ratio of driving wheelbase to overall engine wheelbase 0.42
Overall Wheelbase (engine & tender) (ft / m)35.83 / 10.92
Axle Loading (Maximum Weight per Axle) (lbs / kg)41,440 / 18,797
Weight on Drivers (lbs / kg)116,816 / 52,987
Engine Weight (lbs / kg)185,024 / 83,926
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)185,024 / 83,926
Tender Water Capacity (gals / ML)2000 / 7.58
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 2.80 / 3
Minimum weight of rail (calculated) (lb/yd / kg/m)65 / 32.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)72 / 1829
Boiler Pressure (psi / kPa)200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)19" x 28" / 483x711
Tractive Effort (lbs / kg)23,866 / 10825.45
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.89
Heating Ability
Tubes (number - dia) (in / mm)175 - 1.75" / 44
Flues (number - dia) (in / mm)21 - 5.5" / 140
Flue/Tube length (ft / m)12.50 / 3.81
Firebox Area (sq ft / m2)135 / 12.54
Grate Area (sq ft / m2)25 / 2.32
Evaporative Heating Surface (sq ft / m2)1526 / 141.77
Superheating Surface (sq ft / m2)203 / 18.86
Combined Heating Surface (sq ft / m2)1729 / 160.63
Evaporative Heating Surface/Cylinder Volume166.08
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation5000
Same as above plus superheater percentage5600
Same as above but substitute firebox area for grate area30,240
Power L110,521
Power MT595.68

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