SR W class

Infobox Locomotive
powertype=Steam
name = SR Class W Haresnape, Brian: "Maunsell Locomotives - a pictorial history" (Ian Allan Ltd, 1977), ISBN 0711007438]
designer = Richard Maunsell
builder = SR Eastleigh/Ashford Works
builddate = 1932 to 1936
totalproduction = 15
whytetype = 2-6-4
gauge = RailGauge|ussg
leadingsize = 3 ft 1 in (0.94 m)
driversize = 5 ft 6 in (1.7 m)
trailingsize = 3 ft 1 in (0.94 m)
length = 44 ft 0.25 in (13.4 m)
weight = 90 tons 14 cwt (92.1 tonnes)
fueltype = coal
fuelc
cwt (3.5 tonnes)
waterc

cylindercount = 3
cylindersize = 16.5 in × 24 in (42 cm × 61 cm)
boilerpressure = 200 lbf/in² (1,378 kPa)
tractiveeffort = 29,452 lbf (130.92 kN)

The SR Class W were 3-cylinder 2-6-4 tank engines designed in 1931 by Richard Maunsell for use on the Southern Railway . They were introduced in 1932 and constructed at Eastleigh and Ashford. The class was intended for short distance, inter-company/regional freight traffic transfer in London, and were standardised with parts from the N, N1 and U1 classes.

Construction history

The requirement of fast freight transfer locomotive on London's railway network provided a challenge for Richard Maunsell, because the electrified suburban lines were busy with commuter traffic that took priority over freight workings. The design brief caled for a powerful locomotive that was able to climb the steep gradients over the flying junctions that were to be found all over the Southern Railway's London network. The ability to operate over tight curves and be able to move from a standstill on the aforementioned gradients were also key considerations that needed to be incorporated into the design. Haresnape, Brian: "Maunsell Locomotives - a pictorial history" (Ian Allan Ltd, 1977), ISBN 0-7110-0743-8]

The SR Z Class was considered at first, but due to the specialist characteristics of the design as a yard engine for marshalling freight, they were not deemed fit for the purpose of hauling loads under the tight timings of London's railway system. As a result of the rebuilding of the 'River' K Class 2-6-4 tank engines following the Sevenoaks Rail Disaster, the surplus bogies and leading wheels were earmarked for the new design. The 2-6-4 wheel arrangement was settled upon as being ideal for intensive suburban routes, and the use of parts from the K Class and the same boiler as used on the N, N1 and U1 classes enabled the standardization of Southern locomotives to continue. [ Southern E-Group (2004) [http://www.semgonline.com/steam/wclass_1.html] , Retrieved April 20, 2007. For details on the interchangability of the design with other classes.]

The resultant design, the W Class tank, was introduced in 1932, and were built in two batches, the initial consisting of five locomotives, the second of ten locomotives arriving in 1935–1936. [ Railway Magazine, 1932, 70, 152 For information on the introduction of the class in 1932. ] The first batch was constructed at Eastleigh, with the second at Ashford. These 3 cylinder locomotives were provided with Walschaerts valve gear, and heavy braking equipment to cater for fitted and unfitted freight wagons that were in circulation at the time. With this in mind, the class were unusually provided with extra braking on the bogies and trailing wheels. [ Southern E-Group (2004) [http://www.semgonline.com/steam/wclass_1.html] , Retrieved April 20, 2007. For details on the unusual braking design.]

Variations

The two batches differed from each other because the Eastleigh batch had gravity sanding capability and steam regulators on the right hand side, whilst the Ashford batch had steam sanding and regulators on the left, as was common on most other classes of Southern locomotives.

Modifications

The first batch was modified between 1959 and 1960 to incorporate steam sanding, as this was already present on the Ashford batch. The right hand driving, however, remained. [ Southern E-Group (2004) [http://www.semgonline.com/steam/wclass_1.html] , Retrieved April 20, 2007. For details on the steam sanding.]

Livery and numbering

Southern

The first batch was turned out in black livery with green lining, and were numbered 1911–1915 with 'Southern' in yellow on the water tanks. The Ashford batch was outshopped in unlined black livery, and the initial batch were also converted to this new livery. These locomotives were numbered 1916–1925.

Post-1948 (nationalisation)

The locomotives retained their freight black liveries, and the BR crest was placed on the water tank sides. Numbering was per the BR standard numbering system, in the range 31911–31925.Ian Allan ABC of British Railways Locomotives, winter 1958–59 edition]

Operational details

They were generally well liked by their crews apart from the fact that the driver was on the right hand side of the Eastleigh batch, which made accurate stopping difficult when signalling was predominantly on the left on the Southern network. [ "Reflections on Southern Steam": Strathwood, Boat of Garten.] This would have meant that the fireman was frequently utilised as lookout on the left hand side.

The class was mainly used around London and on the ex-LBSCR routes on inter-company/regional transfer freight duties, and the class hardly ever handled passenger stock. Haresnape, Brian: "Maunsell Locomotives - a pictorial history" (Ian Allan Ltd, 1977), ISBN 0-7110-0743-8] The class began to be withdrawn from service in 1963, with the last removed from the books in 1964. No examples of this class of locomotive survived into preservation.

References

Further reading

*Ian Allan ABC of British Railways Locomotives, winter 1958–59 edition

External links

* [http://www.semgonline.com/steam/wclass_1.html SEMG gallery]