{{Short description|Class of British steam locomotives}} {{Use dmy dates|date=January 2017}} {{Use British English|date=January 2017}} {{more footnotes|date=February 2015}} {{Infobox locomotive |name = Great Central Railway class 8H |powertype = Steam |image = Dunford Bridge Station geograph-2211447.jpg |caption = 69901 at Dunford Bridge on the Woodhead Line in 1950 |designer = John G. Robinson |builder = |builddate = 1907 (4), 1932 (2) |totalproduction = 6 |whytetype = 0-8-4T |uicclass = D2′ n3t, later D2′ h3t |gauge = {{track gauge|ussg}} |driverdiameter = {{convert|4|ft|8|in|m|3|abbr=on}} |locoweight = S1/1: {{long ton|99|6|}}<br>S1/2: {{long ton|99|2|}}<br>S1/3: {{long ton|99|1|}} |trailingdiameter = {{convert|3|ft|2|in|m|3|abbr=on}} |fueltype = Coal |boilerpressure = {{convert|180|psi|MPa|2|abbr=on}} |tractiveeffort = {{convert|34525|lbf|kN|1|abbr=on}} |cylindercount = Three |cylindersize = {{convert|18|x|26|in|mm|0|abbr=on}} |valvegear = Stephenson |valvetype = Slide valves |operator = {{unbulleted list|Great Central Railway| → London and North Eastern Railway| → British Railways}} |operatorclass = {{unbulleted list|GCR: 8H|LNER: S1}} |powerclass = |fleetnumbers = {{unbulleted list|GCR: 1170–1173|LNER: 6170–6173; later 9900–9905|BR: 69900–69905}} |withdrawndate = 1955–1957 |disposition = All scrapped }} The '''Great Central Railway Class 8H''' (LNER Class S1) was a class of 0-8-4T steam tank locomotives designed by John G. Robinson for hump shunting at Wath marshalling yard.
== Overview == Four locomotives were built in 1907/1908 for the Great Central Railway. They were fitted with three cylinders. This gave a more even torque than with a 2-cylinder locomotive and reduced the risk of wheelslip under heavy load. All four passed into London and North Eastern Railway ownership at the 1923 grouping. At the time all four locomotives were allocated to Mexborough engine shed.<ref>{{cite book|last1=Yeadon|first1=W B|title=LNER Locomotive allocations 1 January 1923|date=1996|publisher=Challenger Publications|location=Oldham|isbn=1-899624-19-8|page=10}}</ref>
These were powerful locomotives but even more power was required so, in 1930, one locomotive was fitted with a superheater and a booster engine and classified S1/2. Two new locomotives (with superheaters and boosters) were built by the LNER in 1932 and classified S1/3. The remaining (non-booster) locomotives were classified S1/1 and were also fitted with superheaters. All the boosters were removed in 1943.
All six locomotives passed into British Railways ownership in 1948 and were numbered '''69900-69905'''.
== Dimensions == * Locomotive weight: ** S1/1, 99 tons 6 cwt ** S1/2, 99 tons 2 cwt ** S1/3, 99 tons 1 cwt * Superheater: ** S1/1, No, but fitted later ** S1/2, Yes ** S1/3, Yes * Tractive effort, {{convert|34525|lbf|kN|1|abbr=on}} ** Booster tractive effort, {{convert|12373|lbf|kN|1|abbr=on}} *** Combined tractive effort, {{convert|46896|lbf|kN|1|abbr=on}}
For terminology, see Steam locomotive components
== References == {{Reflist}} * {{cite book| title=Ian Allan ABC of British Railways Locomotives, part 4| edition=1948| page=56}} * {{cite book |last=Casserley |first=H.C. |author2=S. W. Johnston |orig-year=1966|year=1974 |title=Locomotives at the Grouping 2: London & North Eastern Railway |location=Shepperton, Surrey |publisher=Ian Allan Limited |isbn=0-7110-0553-2 }} == External links == {{Commons category|GCR class 8H / LNER class S1}} * [http://www.lner.info/locos/S/s1.shtml LNER Encyclopedia]
{{LNER Locomotives}}
{{DEFAULTSORT:GCR Class 08H}} 08H Category:0-8-4T locomotives Category:Railway locomotives introduced in 1907 Category:Scrapped locomotives Category:Standard-gauge steam locomotives of Great Britain Category:Shunting locomotives