LSWR K10 class
|K10 number 386 at Eastleigh, 1950|
|Builder||LSWR Nine Elms Works|
|Gauge||4 ft 8 1⁄2 in (1,435 mm)|
|3 ft 7 in (1.12 m)|
|Driver diameter||5ft 7in (1.7 m)|
|Length||ft in ( m)|
|Locomotive weight||46 tons 14 cwt (47.4 tonnes)|
|Fuel capacity||5 tons (5.1 tonnes)|
|Water capacity||4,000 imp. gal ( 18.2 m3)|
|Boiler pressure||175 lbf/in²|
|Cylinder size||18.5in x 26in (470mm × 660mm)|
|Tractive effort||19,755 lbf|
|Career||London and South Western Railway, Southern Railway (Great Britain), Southern Region of British Railways|
The London and South Western Railway K10 Class was a class of 40 4-4-0 steam locomotives designed for mixed traffic work. They were introduced on the London and South Western Railway in 1901 and 1902 to the design of Dugald Drummond, where they earned the nickname "Small Hoppers".
In order to satisfy a pressing requirement for mixed-traffic locomotives, Drummond adopted the solution of a small-wheeled 4-4-0 he had previously employed on the Caledonian Railway. The resulting K10 had the same 5' 7" diameter coupled wheels as the M7 and the boiler was interchangeable with the M7, 700 and C8 classes
Construction history 
Forty of the class were subsequently outshopped from the LSWR's Nine Elms Locomotive Works. They were generally paired with a 6-wheel tender because of their intended short journey lengths, which included local stopping trains and medium-level freight haulage, but as with the later L11 class, some could occasionally be seen with a 4000 gallon "watercart" tender for longer trips.
- Construction table
||344–345, 347, 393–394|
Livery and numbering 
LSWR and Southern 
Livery under the LSWR was Drummond's LSWR Passenger Sage Green, with purple-brown edging and black and white lining. Under Southern Railway ownership from grouping in 1923, the locomotives were outshopped in Richard Maunsell's darker version of the LSWR Sage Green with yellow lettering on the tender, with black and white lining. This livery was continued under Oliver Bulleid despite his experimentations with Malachite green, though the 'Southern' lettering on the tender was changed to the 'Sunshine Yellow' style. During the Second World War, members of the class outshopped form overhaul were turned out in wartime black. The class was haphazardly numbered by the LSWR. Numbering under the Southern retained the LSWR allocations.
Post-1948 (nationalisation) 
Twenty-three passed into British Railways ownership on nationalisation in 1948. Livery after nationalisation was initially Southern livery with 'British Railways' on the tender, and an 'S' prefix on the number. The class was subsequently outshopped in BR Mixed Traffic Black with red and white lining, with the BR crest on the tender. Locomotive numbering was per BR standard practice, from 30135 to 30153 and 30329 to 30394. However, thirteen of the locomotives had been withdrawn by the end of 1948, resulting in gaps in the sequence.
Operational details 
The class shared the same inability to sustain their power over long distances as the C8s, leading to the K10s being employed only on occasional main line trips over short distances. The class therefore gained the nickname of "Small Hoppers" from their crews. The aforementioned defect was not a hindrance, with the class leading an admirable career on secondary routes. Due to the LSWR being primarily a passenger railway, there were few heavy goods services that would have proved too much for the design despite its flaws.
Comparison with L11 
None has survived to be preserved.
- Bradley, D. L. (1986). LSWR Locomotives: The Drummond Classes. Didcot, Oxon: Wild Swan Publications,. ISBN 0-906867-42-8.
- Casserley, H.C. (1971) London and South Western locomotives, incorporating Burtt, F.  LSWR locomotives—a survey. Shepperton, Surrey: Ian Allan Limited.
- Dendy Marshall, C.F.; Kidner, R.W. (1963) . History of the Southern Railway (2nd ed.). Shepperton: Ian Allan. ISBN 0-7110-0059-X.
- Longworth, Hugh (2005). British Railway Steam Locomotives: 1948–1968. Oxford Publishing Company. ISBN 0-86093-593-0.
- Swift, Peter (2006). Maunsell 4-6-0 King Arthur Class. Locomotives in Detail, volume 4. Hinckley: Ian Allan Publishing. ISBN 0-7110-3086-3.
Further reading 
- Ian Allan ABC of British Railways Locomotives, 1949 edition, part 2
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