{{Use dmy dates|date=August 2017}} {{Use British English|date=August 2017}} {{Infobox locomotive |powertype=Steam |name = NER Class R1 <br> LNER Class D21 |image = Every boy's book of railways and steamships (1911) (14758974955).jpg |caption = |designer = Wilson Worsdell |boiler = {{convert|5|ft|6|in|abbr=on}} diameter |builder = NER Gateshead works |builddate = 1908-1909 |totalproduction = 10 |whytetype = 4-4-0 |gauge = {{track gauge|uksg}} |leadingdiameter = {{convert|3|ft|7+1/4|in|abbr=on}} |driverdiameter = {{convert|6|ft|10|in|abbr=on}} |length = |wheelbase = {{convert|23|ft|9|in|abbr=on}} engine <br> {{convert|12|ft|8|in|abbr=on}} tender <br> {{convert|45|ft|10+3/4|in|abbr=on}} total |locoweight = |tenderweight = |locotenderweight = |axleload = {{convert|20.8|LT|abbr=on}} |fueltype = coal |fuelcap = |watercap = |cylindercount = two inside |cylindersize = {{convert|19|x|26|in|abbr=on}} |boilerpressure = {{convert|175|psi|MPa|abbr=on}} |totalsurface = |firearea = |fireboxarea = |tubearea = |fluearea = |superheaterarea = |tractiveeffort = {{convert|17026|lbf|kN|abbr=on}} |valvegear = Stephenson |operator = North Eastern Railway<br/>London and North Eastern Railway |powerclass = |operatorclass= |retiredate = 1942-1946 |disposition = All scrapped }}{{Short description|1908/1909 built British Class of 4-4-0 Locomotives (1908-1846)}} The '''NER Class R1''' (LNER Class D21) was a class of 4-4-0 steam locomotives of the North Eastern Railway. The class was designed by Wilson Worsdell and built from 1908 to 1909.<ref name="LNER, D21" />
==Design== The design was similar to that of the NER Class R (LNER Class D20) but a larger boiler was used. Boiler pressure was initially {{convert|225|psi|MPa|abbr=on}}.
Towards the end of construction the work was to be moved from Gateshead to Darlington Works. However the initial locomotive assembled as Darlington was failed as unfit to drive and subsequent investigations established that the coupling rod centres were not equal, resulting in a change of Works Manager at Darlington.<ref>{{cite magazine| last = Hughes| first = Geoff| date = August 1992| title = Talking to Thompson part II| magazine = Steam World| issue = 62|location = Peterborough| publisher = EMAP Apex Publications}}</ref>
==Modifications== Boiler pressure was reduced to 180 psi (1.24 MPa) at an unknown date. Superheaters were fitted between 1912 and 1915 and, at the same time, boiler pressure was further reduced to {{convert|160|psi|MPa|abbr=on}}. It was standard NER practice to reduce boiler pressure when fitting a superheater. At some time before the 1923 Grouping, boiler pressure was increased to {{convert|175|psi|MPa|abbr=on}}.
==Use== The R1s were initially used on the Glasgow-Newcastle and York-Newcastle services. However, as loads increased, they were replaced by more powerful locomotive types (like the class Z) and relegated to secondary duties. By 1924, the Gresley A1s started to arrived in large numbers, which displaced the C7s to many of the secondary duties of the D21s, and in particular, York its entire allocation.<ref name="LNER, D21" />
==Withdrawal== They were withdrawn between 1942 and 1946 and none were preserved.
==References== <references> <ref name="LNER, D21" >{{Cite web |title=The W. Worsdell Class D21 (NER Class R1) 4-4-0 Locomotives |website=LNER Encyclopedia |url=https://www.lner.info/locos/D/d21.php }}</ref> </references>
{{LNER Locomotives}}
R1 Category:4-4-0 locomotives Category:2′B h2 locomotives Category:Railway locomotives introduced in 1908 Category:Scrapped locomotives Category:Standard-gauge steam locomotives of Great Britain Category:Passenger locomotives in the United Kingdom