Overview 4-6-2

1 overview

1.1 development
1.2 origin of name
1.3 global popularity
1.4 tank locomotives
1.5 lifespan

overview

the introduction of 4-6-2 design in 1901 has been described veritable milestone in locomotive progress . on many railways worldwide, pacific steam locomotives provided motive power express passenger trains throughout of mid-20th century, before either being superseded larger types in late 1940s , 1950s, or replaced electric or diesel-electric locomotives during 1950s , 1960s. nevertheless, new pacific designs continued built until mid-1950s.

the type considered enlargement of 4-4-2 atlantic type, although prototype had direct relationship 4-6-0 ten-wheeler , 2-6-2 prairie, being combination of 2 types. success of type can attributed combination of four-wheel leading truck provided better stability @ speed 2-6-2 prairie, 6 driving wheels allowed larger boiler , application of more tractive effort earlier 4-4-2 atlantic, , two-wheel trailing truck, first used on new zealand 2-6-2 prairie of 1885. permitted firebox located behind high driving wheels , thereby allowed both wide , deep, unlike 4-6-0 ten-wheeler had either narrow , deep firebox between driving wheels or wide , shallow 1 above.

the type well-suited high speed running. world speed record steam traction of 126 miles per hour (203 kilometres per hour) has been held british pacific locomotive, mallard, since 3 july 1938.

development

the 2 earliest 4-6-2 locomotives, both created in united states of america, experimental designs not perpetuated. in 1887, lehigh valley railroad experimented 4-6-0 ten-wheeler design strong s patent firebox, cylindrical device behind cab required extension of frame , addition of 2 trailing wheels support it. in 1889, chicago, milwaukee , st. paul railway rebuilt conventional 4-6-0 trailing wheels means of reducing axle load.

in 1896, 6 q class 4-6-2 tank locomotives introduced on western australian government railways.

the first true pacific, designed such large firebox aft of coupled wheels, ordered in 1901 new zealand railways department (nzr) baldwin locomotive works of philadelphia, pennsylvania. nzr chief mechanical engineer, a.l. beattie, ordered thirteen new q class locomotives sufficiently large firebox able efficiently burn poor grade lignite coal eastern south island mines. before baldwin had completed order new zealand, engineers realised advantages of new type , incorporated standard designs other customers. design adopted designers throughout world.

origin of name

there different opinions concerning origin of name pacific. design natural enlargement of existing baldwin 4-4-2 atlantic type, type name may in recognition of fact new zealand designer had first proposed it. usually, however, new wheel arrangements named for, or named by, railroad first used type in united states. in case of pacific, missouri pacific railroad in 1902.

in cape of hope in south africa, first pacifics delivered kitson , company in 1903 , designated karoo class, region of cape western system of cape government railways designed work in.

global popularity

the pacific type used on mainline railways around world. railways of new zealand , australia first in world run large numbers of pacific locomotives, having introduced 4-6-2 types in 1901 , 1902 respectively , operating them until 1960s.

builder s photograph of altoona-built k5 no. 5698, 1929

during first half of 20th century, pacific rapidly became predominant passenger steam power in north america. between 1902 , 1930, 6,800 locomotives of type built north american manufacturers service in united states , canada. exported locomotives included, 7,300 built in total. 45% of these built american locomotive company (alco) became main builder of type, , 28% baldwin. large numbers used in south america, of supplied manufacturers in united kingdom, united states , germany.

cape government railways enlarged karoo class, sar class 5

africa third continent upon pacific regularly used, following introduction of karoo class on cape government railways in cape of hope in 1903. earliest african examples built in united kingdom kitson , company.

the earliest examples of pacific in europe 2 french prototypes, introduced in 1907 , designed compagnie du chemin de fer de paris à orléans (po) overcome insufficient power of 4-4-2 atlantics. within few weeks, these followed german pacific type that, although designed in 1905, entered service in late 1907. next british type, introduced in january 1908. outbreak of first world war, type being used on railways of continental europe.

the pacific type introduced asia in 1907, same year first used in europe. 1920s, pacifics being used many railways throughout asian continent.

in 1923, pacific gave name arthur honegger s orchestral work, pacific 231, reflectively interprets emotive sounds of steam locomotive. (231 after french system of counting axles rather wheels.)

tank locomotives

during first 2 decades of 20th century, pacific wheel arrangement enjoyed limited popularity on tank locomotives. on 4-6-2t locomotive, trailing wheels support coal bunker rather enlarged firebox , such locomotive therefore tank engine version of 4-6-0 ten-wheeler tender locomotive. indeed, many of earliest examples either rebuilt tender locomotives or shared basic design.

around 1920, became apparent designers 4-6-2t wheel arrangement allowed limited bunker size purposes, result later designs of large suburban tank classes of 4-6-4t hudson or 2-6-4t adriatic wheel arrangement.

lifespan

the lner peppercorn class a1 60163 tornado, built in 2008

the pacific became major express passenger locomotive type on many railways throughout 1920s, 1930s , 1940s. examples built fast freight , mixed traffic duties. however, due increasing weight of trains during 1940s, larger developments of type became necessary in united states , elsewhere. notable of these 4-6-4 hudson or baltic type, had four-wheel trailing bogie permitted larger firebox, albeit @ loss of adhesive weight, , 4-8-2 mountain type used pair of driving wheels deliver more tractive effort rails. nevertheless, pacific type remained used on express passenger trains until end of steam traction. last examples built in united kingdom , japan in mid-1950s. british railways introduced standard class 6 , class 7 designs in 1951 , 1952, , final united kingdom design, standard class 8, in 1954.

however, story of 4-6-2 type did not end in 1960s. 1 further mainline example of lner peppercorn class a1, no. 60163 tornado, completed @ darlington a1 steam locomotive trust in 2008. designed meet modern safety , certification standards, tornado runs on united kingdom’s rail network , on mainline-connected heritage railways.