NER Class X

{{Use dmy dates|date=December 2017}}

{{Use British English|date=December 2017}}

{{Infobox locomotive

| name = NER Class X
LNER Class T1

| image = Stockton Locomotive Yard geograph-2358822-by-Ben-Brooksbank.jpg

| alt =

| caption = No. 69919 at Stockton Locomotive Depot 1954

| powertype = Steam

| designer = Wilson Worsdell

| builder = {{ubl|NER Gateshead Works (10)|Darlington Works (5)}}

| ordernumber =

| serialnumber =

| buildmodel =

| builddate = 1909–1910 (10) and 1925 (5)

| totalproduction = 15

| rebuilder =

| rebuilddate =

| numberrebuilt =

| whytetype = 4-8-0T

| uicclass = 2′D n2t

| driver =

| gauge = {{track gauge|ussg}}

| leadingdiameter = {{convert|3|ft|1+1/4|in|m|3|abbr=on}}

| driverdiameter =

| coupleddiameter = {{convert|4|ft|7+1/4|in|m|3|abbr=on}}

| minimumcurve =

| wheelbase = {{convert|29|ft|0|in|m|3|abbr=on}}

| engine total =

| leading =

| drivers =

| coupled =

| trailing =

| tender total =

| tendertruck =

| tenderbogie =

| pivotcentres =

| wheelspacing =

| length = {{convert|42|ft|1|in|m|3|abbr=on}}

| over couplers =

| over bufferbeams=

| width =

| height =

| frametype =

| axleload = {{convert|18.00|LT|abbr=on}}

| leadingbogie/pony=

| coupled all =

| coupled 1 =

| coupled 2 =

| coupled 3 =

| coupled 4 =

| coupled 5 =

| coupled 6 =

| coupled 7 =

| coupled 8 =

| trail bogie/pony=

| tenderbogieload =

| tenderaxle =

| weightondrivers = {{convert|67.60|LT|abbr=on}}

| locoweight = {{convert|85.40|LT|abbr=on}}

| fueltype = Coal

| fuelcap = {{convert|4.25|LT|abbr=on}}

| watercap = {{convert|2500|impgal|abbr=on}}

| sandcap =

| fireboxtype =

| firearea = {{convert|23|sqft|abbr=on}}

| boiler =

| boilertype =

| pitch =

| diameterinside =

| lengthinside =

| smalltubediameter=

| largetubediameter=

| boilerpressure = {{convert|175|lbf/in2|MPa|abbr=on}}

| safetyvalvetype =

| feedwaterheater =

| totalsurface = {{convert|1295|sqft|m2|abbr=on}}

| tubearea = {{convert|1168|sqft|m2|abbr=on}}

| fluearea =

| tubesandflues =

| fireboxarea = {{convert|127|sqft|m2|abbr=on}}

| superheatertype =

| superheaterarea =

| cylindercount = Three

| cylindersize = {{convert|18|x|26|in|mm|0|abbr=on}}

| valvegear = Stephenson

| valvetype = {{convert|8+3/4|in|mm|0|adj=on}} piston valves

| valvetravel =

| valvelap =

| valvelead =

| transmission =

| trainheating =

| locobrakes =

| locobrakeforce =

| trainbrakes =

| safety =

| coupling =

| maxspeed =

| poweroutput =

| tractiveeffort = {{convert|34080|lbf|kN|abbr=on}}

| factorofadhesion =

| operator = {{ubl|North Eastern Railway|London and North Eastern Railway|British Railways}}

| operatorclass =

| powerclass = BR: 7F, 5F from May 1953

| numinclass =

| fleetnumbers =

| officialname =

| nicknames =

| axleloadclass = LNER/BR: Route availability 8

| locale =

| deliverydate =

| firstrundate =

| lastrundate =

| withdrawndate = 1937, 1955–1961

| scrapdate =

| disposition = All scrapped

| notes =

}}

The NER Class X (LNER Class T1) was a class of 4-8-0T tank locomotive designed by Wilson Worsdell for the North Eastern Railway.{{sfn|Boddy|Brown|Fry|Hennigan|1977|p=29}} They were intended for use as powerful shunting engines to arrange and move coal wagons for loading into ships.{{sfn|Boddy|Brown|Fry|Hennigan|1977|p=29}} In total 15 were built, 10 by the NER between 1909 and 1910, and a further five in 1925 by the London and North Eastern Railway (LNER).{{sfn|Boddy|Brown|Fry|Hennigan|1977|p=29}} They had three cylinders with divided drive: the inside cylinder driving the leading axle, the outside cylinders driving the centre.{{sfn|Ahrons|1927|p=338}}