GWR 3100 Class

{{Use dmy dates|date=January 2018}}

{{Use British English|date=January 2018}}

{{refimprove|date=March 2014}}

{{about|the 5 locomotives rebuilt in 1938/9 from the 3150 Class|the 40 locomotives built in 1903–06 as the 3100 class|GWR 5100 Class}}

{{Infobox Locomotive

| powertype = Steam

| name = GWR 3100 Class

| image =

| caption =

| designer = Churchward
(rebuilt by Collett)

| builder = GWR Swindon Works

| ordernumber = Lot 319

| builddate = 1906

| rebuilddate = 1938

| numberrebuilt = 5

| whytetype = 2-6-2T

| uicclass = 1'C1 h2t

| gauge = {{track gauge|uksg|allk=on}}

| leadingdiameter = {{convert|3|ft|0|in|m|3|abbr=on}}

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

| trailingdiameter = {{convert|3|ft|8|in|m|3|abbr=on}}

| minimumcurve = {{convert|6|chain|0}} normal,
{{convert|5|chain|0}} slow

| length = {{convert|41|ft|0|in|m|2|abbr=on}} over buffers

| width = {{convert|8|ft|11+1/4|in|m|3|abbr=on}}

| height = {{convert|13|ft|2|in|m|3|abbr=on}}

| axleload = {{long ton|19|3}}
({{convert|19|LT|3|Lcwt|ST|1|abbr=on|disp=output only}}) full

| weightondrivers = {{long ton|57|6}}
({{convert|57|LT|6|Lcwt|ST|1|abbr=on|disp=output only}}) full

| locoweight = {{long ton|81|9}}
({{convert|81|LT|9|Lcwt|ST|1|abbr=on|disp=output only}}) full

| fueltype = Coal

| fuelcap =

| watercap = {{convert|2000|impgal|abbr=on}}

| boiler = GWR Standard No. 4

| boilerpressure = {{convert|225|lbf/in2|MPa|abbr=on}}

| firearea = {{convert|20.56|sqft|m2|abbr=on}}

| tubearea = {{convert|1349|sqft|m2|abbr=on}}

| fireboxarea = {{convert|128.72|sqft|m2|abbr=on}}

| superheatertype = 4-element or 6-element

| superheaterarea = 4-element: {{convert|136.64|sqft|m2|abbr=on}},
6-element: {{convert|181.10|sqft|m2|abbr=on}}

| cylindercount = Two, outside

| cylindersize = {{convert|18.5|x|30|in|mm|0|abbr=on}}

| tractiveeffort = {{convert|31170|lbf|kN|abbr=on}}

| operator = GWR » BR

| operatorclass = 3100

| fleetnumbers = 3100–3104

| powerclass = GWR: D,
BR: 4MT

| axleloadclass = GWR: Red

| withdrawndate = 1957–1960

| disposition = All scrapped

}}

The Great Western Railway (GWR) 3100 Class was a class of 2-6-2T side tank steam locomotive.