MGWR Class B

{{Use dmy dates|date=April 2022}}

{{Infobox locomotive

| name = B class

| image =

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| powertype = Steam

| designer = Edward Cusack

| builder = North British

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| buildmodel =

| builddate = 1904

| totalproduction = 6

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| whytetype = 0-6-0

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| driver =

| gauge = {{track gauge|Irish}}

| leadingdiameter =

| driverdiameter = {{convert|5|ft|3|in|mm|abbr=on}}

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| operator = Midland Great Western Railway
Great Southern Railways
CIÉ

| operatorclass =

| powerclass =

| numinclass = 4

| fleetnumbers = MGWR 143-146
GSR 646-649

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| locale = Ireland

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| withdrawndate = 1930-1939

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The Midland Great Western Railway (MGWR) B Class 0-6-0 was a class of 4 locomotives built at North British Locomotive Company in 1904. In 1925 they were allocated Great Southern Railways (GSR) Class 646 / Inchicore Class J2.{{cite book| title=The Midland Great Western Railway of Ireland - An illustrated History|last=Shepherd|first=Ernie|publisher=Midland Publishing Limited|publication-date=1994|ISBN=1-85780-008-7|pages=89,130}}{{cite book|title=Locomotives of the GSR|pages=207|isbn=9781906578268|last1=Clements|first1=Jeremy|last2=McMahon|first2=Michael|date=2008|publisher=Colourpoint Books}}

class="wikitable"
MGWR No. !Name !Built !GSR No. !Withdrawn
143	Canada	1904	646	1933
144	Australia	1904	647	1930
145	India	1904	648	1939
146	Africa	1904	649	1939

The MGWR Class B was an attempt at a more powerful 0-6-0 locomotive than the existing Class L. Like the Class A 4-4-0 which they shared some components they were weight restricted to the Dublin-Galway on the MGWR. They were rebuilt 1916/17 with superheating. On scrapping some of their tenders were givin to Class A locomotives.