Midland Railway 2601 Class

{{Infobox locomotive |powertype=Steam |name = Midland Railway 2601 Class |image = Midland Railway No. 2601.jpg |caption = |designer = [[Samuel Waite Johnson]] |builder = [[Derby Works]] |builddate = 1899–1900 |totalproduction = 10 |whytetype = [[4-2-2]] |uicclass = 2′A1 n2 |gauge = {{Track gauge|uksg|allk=on}} |leadingdiameter = |driverdiameter = {{convert|7|ft|9+1/2|in|m|2|abbr=on}}<ref name="Baxter1982135" >{{Baxter: British Locomotive Catalogue 1825–1923|page=135|volume=3A}}</ref> |length = |axleload = |locoweight= {{convert|50|LT|3|lcwt|abbr=on}} |tenderweight= |locotenderweight= |fueltype = [[Coal]] |fuelcap = |watercap = |firearea = |boiler = MR type F<ref name="BR database, 2601 class" /> |boilerpressure = {{convert|180|lbf/in2|kPa|abbr=on}} <ref name="Baxter1982135" /> |cylindercount = Two, inside |cylindersize = {{convert|19+1/2|×|26|in|mm|abbr=on}}<ref name="Baxter1982135" /> |valvegear=Stephenson<ref name="Ahrons, 266" /> |tractiveeffort = {{convert|16131|lbf|kN|1|abbr=on}} |operator={{ubl|[[Midland Railway]]}} |operatorclass= 2601 class |fleetnumbers = {{ubl|''New:'' 2601–2608, 22–23|''1900:'' 2606-2608 became 19-21|''1907:'' 685–694}}<ref name="Baxter1982135" /> |withdrawndate = 1919–1922 |disposition = All scrapped }}

The Midland Railway '''2601 class''' was the last of four classes of [[4-2-2 |4-2-2 steam locomotives]] designed by [[Samuel Waite Johnson|Samuel Johnson]] for the [[Midland Railway]]. They were a development of his [[Midland Railway 115 Class|115 class]] ''Spinners''.{{efn-lr|Midland Railway locomotive class numbering was rather arbitrary, not sequential. Johnson's three classes of 4-2-2 were the 1853, 115 and 2601, in that order.}}

Only 10 were built at [[Derby Works]],<ref name="BR database, 2601 class" /> and none were preserved.

== Design == === The resurgence of singles === Towards the end of the 19th century, the age of the [[single (locomotive)|single-driver locomotive]] was obsolete because the trains, which had become heavier, required pulling forces that could no longer be provided by a single drive axle. When [[steam sanding]] was invented by [[James Gresham (inventor)|James Gresham]] in 1885<ref name="envy" >{{Cite web |access-date= 2 June 2024 |title= James Gresham |url= https://steamindex.com/people/gresham.htm |website=Steamindex }}</ref> this improved the traction of the driving wheels enough that singles were once again a practical design.<ref name="Ahrons, 266" /> There was a resurgence of single designs across a number of railways, such as the GWR's [[GWR 3031 Class|Dean Singles]], Holden's [[GER Class P43|P43]] for the GER and [[Samuel Waite Johnson|Johnson]]'s [[Midland Railway 115 Class|115 class]] ''Spinners'' for the [[Midland Railway]].{{sfnp|Ahrons|1927|pages=294-296}}<ref name="loco-info. 115 2601" /> All of these were used for high-speed passenger services of moderate weight and not usually of the longest distances. This required a locomotive that was powerful,{{efn-lr|Power is the [[product (mathematics)|product]] of both speed and tractive effort.}} with the ability to run at high speeds, but only modest [[tractive effort]].<ref name="RWotW, 27" />

Most used [[double frame]]s and two [[inside cylinders (steam locomotive)|inside cylinders]].<ref name="Ahrons, 266" /> [[Outside frame]]s, and thus double frames, were generally seen as obsolete,{{efn-lr|Although some outside frames persisted for slow [[mineral locomotive|mineral engine]]s such as the GWR ''[[GWR 2600 Class|Aberdare]]s''.}} but this was an issue with coupled wheels and the need for their [[coupling rod]]s to use outside cranks. For singles, especially inside-cylindered singles, this was an irrelevance. The use of inside cylinders also reduced the [[rocking couple]],{{efn-lr|This rocking couple is the unbalanced force from two pistons in [[antiparallel vectors|anti-parallel]], as the pistons move in opposite directions. Any [[couple (mechanics)|couple]] would be multiplied by the spacing between the cylinders, which is several times greater for outside cylinders.}} which could become a problem for outside-cylindered locomotives with short wheelbases at high speed. By using double frames, Johnson's ''Spinners'' had four main axle bearings<ref name="loco-info. 115 2601" /> and thus was not undersized and without continual trouble.{{citation needed|date=July 2024}}

=== 2601 class === A few years after the 115s, Johnson followed these with the slightly improved 2601 class.<ref name="loco-info. 115 2601"/> The cylinder sizes remained the same and the driving wheels increased by {{cvt|1/2|in|mm}}. The only major change was that the [[slide valve]]s were replaced by [[piston valve (steam engine)|piston valve]]s, although the boiler was still un[[superheater|superheated]].<ref name="loco-info. 115 2601" />

The boiler was enlarged, with a larger grate area and a small increase in working pressure from {{cvt|170 to 180|psi|kPa|0}}. The [[steam dome]] was now directly above the driving axle, rather than noticeably ahead of it, as on the 115s. By 1900 Johnson was using the new [[Belpaire firebox]] design for the [[Midland Railway Class 3 4-4-0|4-4-0 ''Belpaires'']], but this firebox was wider than the previous [[round-topped boiler]] and there was insufficient space for it between the tall single drivers.<ref name="Cook, 2000, 30" />

The 6-wheeled [[tender (rail)|tender]] was replaced with an 8-wheeled [[bogie]] design. This provides a further identification feature in photographs between a 115 and a 2601.<ref name="loco-info. 115 2601" />

== History == Between 1887 and 1900, Johnson had no fewer than 95 single locomotives built by [[Derby Works|the railway's own workshops]] in [[Derby]], which differed slightly in structural details. They were used on high-quality express trains and reached speeds of up to {{cvt|90|mph|km/h}}. 2601 ''[[Alexandra of Denmark|Princess of Wales]]'', the first of the class, was exhibited at the [[Paris Exposition of 1900]] and awarded the Grand Prix.<ref name="RWotW, 27" /><ref name="BR database, 2601 Princess of Wales" />

The class was withdrawn between 1919 and 1922, shortly before the [[Railways Act 1921|Grouping]] the following year.<ref name="BR database, 2601 class" />

== Notes == {{notelist-lr}}

== References == <references>

<ref name="loco-info. 115 2601" >{{Cite web |website=loco-info.com |title=Midland classes 115 and 2601 |url=https://www.loco-info.com/view.aspx?id=14939 }}</ref>

<ref name="RWotW, 27" >{{Cite magazine |magazine=Railway Wonders of the World |title=Some Famous Singles |issue=27 |year=1935 |url=https://www.railwaywondersoftheworld.com/singles.html }}</ref>

<ref name="BR database, 2601 class" >{{Cite web |title=MR/LMS Johnson "2601" Class 4-2-2 |website=BR Database |url=https://www.brdatabase.info/locoqry.php?action=class&type=S&id=442206 }}</ref>

<ref name="BR database, 2601 Princess of Wales" >{{Cite web |title=2601 |website=BR Database |url=https://www.brdatabase.info/locoqry.php?action=locodata&id=442206001&type=S&loco=2601 }}</ref>

<ref name="Cook, 2000, 30" >{{cite book |last=Cook |first=A.F. |title=Raising Steam on the LMS: The Evolution of LMS Locomotive Boilers |chapter= |year=2000 |isbn=978-0901115850 |publisher=[[RCTS]] |page=30 }}</ref>

<ref name="Ahrons, 266" >{{Book-Ahrons-British Steam Railway Locomotive|page=266}}</ref>

</references>

[[Category:Midland Railway locomotives|02601]] [[Category:4-2-2 locomotives]] [[Category:Railway locomotives introduced in 1899]] [[Category:Standard-gauge steam locomotives of Great Britain]] [[Category:Passenger locomotives in the United Kingdom]] [[Category:Scrapped locomotives]]