Maunsell "Lord Nelson" class 4-6-0
| Upon becoming the Chief Mechanical Engineer of the newly formed Southern Railway Richard Maunsell assessed the locomotive stock inherited from the pre-grouping companies and devised an improvement programme for types to be retained together with outline plans for a new range of locomotives to his own designs. As was becoming common at the time he proposed a range of "standard" locomotives to meet the future needs of the railway with a large degree of commonality of engineering design and parts. His top express passenger locomotive for the range was eventually to be called the Lord Nelson class. |
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Nº858 Lord Duncan at Bournemouth Central in Southern Railway days. On the left is
departmental vehicle Nº710S.
photograph: Mike Morant Collection |
| Nº30854 Howard of Effingham in BR livery
with all but the first vehicle of the train apparently in plum and spilt milk
livery.
photograph: Mike Morant Collection |
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| Indeed he was set a tough challenge for this specification
by the Chief Operating Manager because the future standard for main line
express trains was to haul a load of 500 tons tare at a start-to-stop average
speed of 55 m.p.h. on not only the South West section but also over the
demanding to operate Eastern section. Maunsell set about this in a systematic
fashion with development work and trials using modified locomotives, and
evaluating and comparing the designs of other companies with the aim of
producing what would be called today a "state of the art" locomotive.
However first there was a pressing need for more express passenger locomotives
for the expanded summer timetable of 1925 and this was met by construction of
additional class N15 engines with an improved
front end.
After considering various options the eventual specification called for a four cylinder 4-6-0 locomotive with cranks set at 135 degrees, the drive divided between the first two coupled axles, 6 ft 7 in diameter driving wheels, a boiler pressure of 220 lb psi and a tractive effort of 33500 lb - the highest of any British express passenger locomotive of the time. One original feature was the settings of the cranks led to eight power impulses per revolution in place of the normal four, leading to eight puffs to be heard for every turn of the wheels! This applied to all except the last of the class, 30865, whic has the more normal four exhaust per revolution. A Belpaire firebox was employed and although a longer boiler had been considered earlier a boiler with tubes the same length as those employed on the N15 class was used. The fire grate was to be unique to the Southern (but not to another railway associated with Swindon) with the rear portion being horizontal and the front steeply inclined providing an area of 33 sq ft, the largest of any British locomotive of the time (although later exceeded by the GWR Castle class). Because the four cylinder design threatened to result in a locomotive heavier than the Civil Engineer's axle loading limit special care was taken in design and construction to keep the locomotive's weight to a minimum. High tensile steel was employed for the motion. Parts which would normally have been left as cast or forged were machined to remove excess metal and the frames were made as thin as practical with additional lightening holes. When constructed the prototype locomotive came out only 1 ton 1 cwt heavier than the N15 class so production models did not employ the latter two weight reducing factors. An increase of almost 33 percent tractive effort for only just over a 1 ton weight gain between the two classes is a tribute to the skilful design. |
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Nº30861 Lord Anson seen here in early BR livery .
photograph: Mike Morant Collection |
| Nº30861 again in the later "Cycling Lion" era livey at Waterloo on 24th March 1957.
photograph: Mike Morant Collection |
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| The prototype was built at Eastleigh in 1926, numbered E850
and was named very popularly after Lord Nelson - which was eventually to become
the designation of the whole class. Maunsell then trialed the prototype in
service for two years and only minor modifications to the front end were
required for the production run. The trials indicated that the design was
capable under ideal operating conditions of meeting the 500 ton/55 mph
specification but in reality it was never required since the deteriorating
economic conditions in the country resulted in the loading of services never
reaching this limit. In fact the heaviest and fastest services of the day
remained within the capabilities of the King Arthur (N15) class. Between 1928
and 1929 fifteen locomotives were constructed at Eastleigh and all were named
after famous British Admirals.
In service the Lord Nelsons were found to be not as free steaming as the King Arthur class which remained the majority of footplate crews' favourite. Performance of the class could be erratic and this was attributed to unfamiliarity with its firing needs. In the hands of an experienced LN crew exceptional performances could be obtained (though on the SW main line it was noted the class always performed far better east of Salisbury than on the demanding section to the west). That there were only ever sixteen engines of the class contributed to the unfamiliarity with the locos by the majority of crews. Despite this the Lord Nelson class was always highly regarded and the contribution to advances in British locomotive design by Richard Maunsell with this class should never be underestimated. The class proved to be very reliable in service and as such it was popular with shed staff. |
| Nº30865 Sir John Hawkins prepares to leave Bournemouth Central with an inter-regional
express which it will haul as far as Oxford. This, the last of the class, was the only LN to have the traditional
four exhaust beats per revolution.
photograph: Mike Morant Collection |
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Nº30856 Sir Francis Drake passing through Surbiton, date unknown.
photograph: Mike Morant Collection |
| Once in service five engines were modified in different ways
to trial further improvements. None of these provided any significant change in
performance and whilst the modifications were not extended to any other members
of the class they were never removed from their trial locomotives. In 1931
authority was given for a sixth trial to modify a LN to a four cylinder
compound with a 250 lb pressure boiler and poppet valves but this was not
pursued. As with the N15 and S15 classes various type tenders were exchanged and six
wheeled tenders were used on the Eastern section.
Upon succeeding Maunsell, Oliver Bulleid improved the class by fitting Lemaître multiple jet blastpipes and larger diameter piston valves. He also introduced the final design of tender, still with 5,000 gallons capacity but with a sharper slope to the bunker floor which helped make the coal tumble forwards more easily. The sides were raised which increased the depth of the bunker. The class was due to be relegated by the arrival of Bulleid's own Pacifics but when his new locomotives had problems the Lord Nelsons deputised, on routes they were allowed to work, and proved their continuing worth. Once BR had rebuilt the Bullied Pacifics the Lord Nelson class finally became relegated from Top Link duties and withdrawals began in 1961 with the whole class being withdrawn by the end of 1962. Only the prototype 30850 (850) has been preserved and is under the care of the Eastleigh Railway Preservation Society. |
| Nº30864 Sir Martin Frobisher was photographed from a
Victoria bound 4 Sub and is seen approaching the carriage cleaning facility
just north of Clapham Junction.
photograph by Mike Morant |
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Nº30856 Lord St Vincent at Waterloo on 30th April 1961, now sporting the final BR steam
crest.
photograph: Gerald T. Robinson/Mike Morant Collection |
| Now preserved as part of the National Collection, Lord Nelson is seen here on display at the Woking
150 event on the 30th May 1988.
photograph by Colin Duff |
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This page was last updated 20 May 2011
