View source for GNR Class O2

{{Short description|British steam locomotive class (1918–1963)}}
{{Use dmy dates|date=April 2017}}
{{Use British English|date=April 2017}}
{{Infobox locomotive
| name = GNR Class O2
| image = Doncaster station geograph-2463320-by-Ben-Brooksbank.jpg
| alt = 
| caption = O2/3 2-8-0 No. 3963 at Doncaster 1947
| powertype = Steam
| designer = [[Nigel Gresley]]
| builder = {{ubl|[[Doncaster Works]] (57)|[[North British Locomotive Co.]] (10)}}
| ordernumber = 
| serialnumber = 
| buildmodel = 
| builddate = 1918, 1921 – 1943
| totalproduction = 67
| rebuilder = 
| rebuilddate = 
| numberrebuilt = 
| whytetype = [[2-8-0]]
| uicclass = 1'Dh3
| driver = <!-- e.g. 1st, 2nd  or 3rd coupled axle -->
| gauge = {{Track gauge|ussg}}
| leadingdiameter = {{convert|2|ft|8|in|m|abbr=on}}
| driverdiameter = <!-- USA terminology -->
| coupleddiameter = {{convert|4|ft|8|in|m|abbr=on}}
| trailingdiameter = 
| tenderdiameter = <!-- tender wheel diameter -->
| minimumcurve = 
| wheelbase = 
| engine total = 
| leading = 
| drivers = <!-- USA terminology -->
| coupled = <!-- British terminology -->
| trailing = 
| tender total = 
| tendertruck = <!-- USA terminology -->
| tenderbogie = <!-- British terminology -->
| wheelspacing = <!-- coupled wheels with assymetrical wheel spacing -->
| length = {{convert|63|ft|3|in|m|2|abbr=on}}
| over couplers = 
| over bufferbeams = 
| width = {{convert|8|ft|9|in|m|abbr=on}}
| height = {{convert|12|ft|11.25|in|m|abbr=on}}
| frametype = 
| axleload = 
| leadingbogie/pony = <!-- load on leading bogie or pony wheel -->
| coupled all = <!-- when the load on all coupled wheels are the same -->
| coupled 1 = <!-- load on 1st coupled wheel -->
| coupled 2 = <!-- load on 2nd coupled wheel -->
| coupled 3 = <!-- etc. -->
| coupled 4 = 
| tenderbogieload = <!-- load per tender bogie, use "Bogie 1:<br/>Bogie 2:" if different -->
| tenderaxle = <!-- use "Axle 1:", etc with "<br/>" for line breaks -->
| weightondrivers = 
| locoweight = {{convert|74.1|-|78.65|LT|abbr=on}}
| tenderweight = {{convert|43.1|-|52|LT|abbr=on}}
| locotenderweight = 
| tendertype = 
| fueltype = Coal
| fuelcap = 
| watercap = 
| tendercap = 
| sandcap = 
| fireboxtype = <!-- Round-top, Belpaire, combustion chamber, etc. -->
| firearea = {{convert|27.5|sqft|m2|abbr=on}}
| boilertype = <!-- Domeless, etc -->
| pitch = <!-- height of boiler centreline above the railhead -->
| diameterinside = {{convert|5|ft|4.75|in|mm|abbr=on}} or {{convert|5|ft|6|in|mm|abbr=on}}
| lengthinside = <!-- distance between tube plates -->
| smalltubediameter = <!-- number of boiler tubes and their outside diameter -->
| largetubediameter = <!-- number of larger tubes, if any, and their outside diameter -->
| boilerpressure = {{convert|180|lbf/in2|MPa|2|abbr=on}}
| safetyvalvetype = <!-- Salter spring balance, Ramsbottom, Pop, etc. -->
| feedwaterheater = 
| totalsurface = {{convert|2032|sqft|m2|abbr=on}}
| tubearea = 
| fluearea = 
| tubesandflues = 
| fireboxarea = 
| superheatertype = 
| superheaterarea = {{convert|430.5|sqft|m2|abbr=on}}
| cylindercount = Three
| cylindersize = {{convert|18+1/2|x|26|in|mm|0|abbr=on}}
| valvegear = {{ubl|Outside: [[Walschaerts valve gear|Walschaerts]]|Inside: [[Gresley conjugated valve gear|Gresley conjugated]]}}
| valvetype = {{convert|8|in|mm|0|adj=on}} piston valves
| valvetravel = 
| valvelap = 
| valvelead = 
| transmission = 
| trainheating = 
| locobrakes = 
| locobrakeforce = 
| trainbrakes = 
| safety = 
| coupling = 
| maxspeed = 
| poweroutput = 
| tractiveeffort = {{convert|36740|lbf|kN|abbr=on}}
| factorofadhesion = 
| operator = {{ubl|[[Great Northern Railway (Great Britain)|Great Northern Railway]]|[[London and North Eastern Railway]]|[[British Railways]]}}
| operatorclass = 
| powerclass = BR: 8F
| numinclass = 
| fleetnumbers = GNR: 461, LNER: 3921-3987, BR: 63921-63987
| officialname = 
| nicknames = 
| axleloadclass = 
| locale = [[Eastern Region of British Railways|Eastern Region]]
| deliverydate = 
| retiredate = 
| withdrawndate = 1948, 1960 – 1963
| scrapdate = 
| disposition = All scrapped
| notes = 
}}
The [[Great Northern Railway (Great Britain)|Great Northern Railway]] (GNR) '''Class O2''' was a class of three-cylinder [[2-8-0]] [[steam locomotive]]s designed by [[Nigel Gresley]] for freight work and built by the GNR from 1921.  Further examples were built by the [[London and North Eastern Railway]] (LNER) from 1924.

==Sub-classes==
The LNER created four subclasses: 
<ref>Ian Allan ABC of British Railways Locomotives, summer 1961 edition, part 4, pp 37–38</ref>
* O2/1, Introduced 1921. Development of experimental Gresley GNR 3-cylinder locomotive (LNER 3921). Subsequently rebuilt with side-window cab and reduced boiler mountings.
* O2/2, Introduced 1924. Development of O2/1 with detail differences.
* O2/3, Introduced 1932. Development of O2/2 with side-window cab and reduced boiler mountings.
* O2/4, Introduced 1943. Rebuilt with 100A ([[LNER Thompson Class B1|B1]] type) boiler and [[smokebox]] extended backwards.

==GNR==
The first models of this class were designed and built under GNR ownership, the first locomotive, 461, was built in May 1918. A batch of ten further O2s was built by the North British Locomotive Co. in 1921.

==LNER==

Fifteen more O2s were built immediately after the [[Railways Act 1921|Grouping]] in 1923. Sixteen more were delivered in 1932 and 1933. Wartime requirements led to the construction of 25 from 1942 to 43 in three batches.

==British Railways==
{{unreferenced section|date=November 2016}}

All 67 locomotives passed to [[British Railways]] (BR) in 1948 and were given BR Numbers 63921–63987, but 63921 (which was the prototype 461, LNER 3921) was quickly scrapped. They served all across the former LNER from Stratford through East Anglia into the East Midlands, primarily hauling coal and iron ore trains. By winter 1955/56, they had all gravitated to Doncaster (36A - 35 locomotives), Grantham (35B - 14 locomotives) and Retford (36E - 17 locomotives). By winter 1962, they were down to 52 locomotives still in much the same locations, the following having been scrapped: 63929/34/44/47/50-55/57-59/70.

By the end of 1963, all members of the class had been scrapped.

==Gallery==
{|
| [[File:Doncaster Locomotive Depot geograph-2463296-by-Ben-Brooksbank.jpg|thumb|O2/2 63942 at Doncaster 1961]]
| [[File:Retford (GC) Locomotive Depot geograph-2463346-by-Ben-Brooksbank.jpg|thumb|O2/4 No. 63966 with side-window cab, band  100A boiler at Retford Locomotive Depot 1962]]
|}

==References==
{{Reflist}}
* British Railways Locomotives Combined Volume Winter 1955/56, part 4, p.&nbsp;32, and the locoshed section, p.&nbsp;71.
* British Railways Locomotives Combined Volume 11/62, p.&nbsp;144
* {{RCTS-LocosLNER|6B|pp=14–32}}

== External links ==
{{Commons category|GNR Class O2 / LNER Class O2}}
* [http://www.lner.info/locos/O/o2.shtml LNER encyclopedia]

{{LNER Locomotives}}

[[Category:Great Northern Railway (Great Britain) locomotives|O2]]
[[Category:1′D h3 locomotives]]
[[Category:Railway locomotives introduced in 1921]]
[[Category:Scrapped locomotives]]
[[Category:NBL locomotives]]
[[Category:Standard-gauge steam locomotives of Great Britain]]
[[Category:Freight locomotives]]
[[Category:2-8-0 locomotives]]