class class british cylinder freight steam locomotive designed based class class locomotives class complex build history spanning years construction examples constructed london hauled freight trains south coast ports west exeter occasional passenger work conjunction larger wheeled class counterparts following grouping railway companies chief mechanical engineer newly formed company increased class strength locomotives incorporated improvements notably steam circuit locomotive loading gauge allowing operate routes height width restrictions new locomotives built service years locomotives continued operation british railways seven examples preserved use heritage railways currently varying states repair background world war management wished address requirement modern standard heavy freight locomotive work london freight yards southwest england lacked existing freight designs capable undertaking task new design needed serve south coast ports portsmouth southampton design power traffic including milk trains required fast transit london opportunity develop recent class design applying locomotive concept purpose built freight design built order number order number gave class construction history class built february december batch design outline world war incorporated lessons learned operation class design provide basis future maintenance class components similar design class passenger locomotive overall appearance details boiler cylinders valve gear classes boiler classes opposed parallel boiler class major difference smaller diameter driving wheels smaller diameter wheels gave better traction essential fast freight locomotive sixteen service allocated london area including new yard despite sound changes original design grouping railway companies retired amalgamated given newly created post decided revise cylinder arrangement locomotive delayed construction locomotives modifications modifications service evident locomotive crews taken sound design better achieving consistent locomotive capable undertaking tasks intended successful implementation modifications permission given management second batch locomotives constructed second batch modifications included increasing boiler pressure psi psi reduction cylinder bore half inch modified operation southern new composite loading gauge differed previous having style cab usually fitted locomotives unlike original cab favoured style cab steel construction roof flush cab sides inspired standard cab developed midland railway number midland features introduced chief transferred midland railway variants cab standard new locomotives converted tank engines modifications included valve travel fitting larger outside steam pipes flow steam cylinders locomotives revised design built given imperial gal wheeled use central section allowed locomotive turned shorter found network new rest class equipped imperial gal wheel tender allowed class operate extended freight routes western section measures undertaken soon fact parts swapped classes locomotives overhaul batch benefits gained modifications showed improved performance batch built predecessors batch ordered coinciding volume freight economic depression meant class completed weight saving modifications undertaken batch final modification applied class time locomotives equipped smoke improve visibility travelling speed modification feature common influenced designs operational details modification class regarded locomotive crews excellent goods engine best known working heavy night express goods trains exeter southampton capable passenger engines able situations shortage passenger locomotives peak holiday periods spent working lives western section inter regional order increase maintenance efficiency locomotives lower boiler pressure concentrated southern railway london freight depot yard featured allocated salisbury demonstrating nature class despite design year newer king arthur class counterparts dual freight passenger abilities retired british railways plan number final member class operation returning january work farewell rail tour accidents incidents summer locomotive hauling freight train overran signals trap points ash hampshire preservation seven preserved examples seen heritage railways country surviving members class purchased barry currently steam preservation operated mainline certain points career running numbering ownership painted late dark black light green lining applied freight designs lettering numbering located tender respectively initials located tender continued number displayed tender darker olive type green substituted entire class painted wheels green black tyres numbers replaced cast oval plate southern railway edge number centre yellow southern locomotive number transfers placed tender tank locomotives given black green lining remained guise little modification slight modification occurred second world war introduced sunshine yellow lettering numbering modification application green shaded sunshine lettering war finally reverted sunshine yellow lettering numbering war built delivered authorised british railways period british railways transitional entire class painted british railways lining numbering located british railways crest tender sides numbering initially prefix locomotives eventually numbered british railways standard numbering system according batch numbered series batch second batch
LSWR S15 class