What is British Rail 10100?
{{Infobox locomotive |name = British Railways 10100 |powertype = Diesel-mechanical |image = Derby works fell diesel geograph-2390424-by-Ben-Brooksbank.jpg |caption = The Fell Diesel at Derby Works in June 1957 |builder = [[London, Midland and Scottish Railway|LMS]], [[Derby Works]] |ordernumber = |builddate = 1951 |whytetype = [[4-8-4]] |uicclass = [[2′D2′]] |gauge = {{Track gauge|ussg|allk=on}} |leadingdiameter = {{convert|39|in|m|3|abbr=on}} |driverdiameter = {{convert|51|in|m|3|abbr=on}} |minimumcurve = {{convert|5|chain|m|0|lk=on}} |wheelbase = {{convert|41|ft|4|in|abbr=on}} |length = {{convert|50|ft|0|in|abbr=on}} |width = {{convert|9|ft|0|in|abbr=on}} |height = {{convert|13|ft|0|in|abbr=on}} |locoweight = {{convert|120|LT|t ST|sigfig=3}} |fuelcap = {{convert|720|impgal|abbr=on}} |coolantcap = {{convert|60|impgal|abbr=on}} |watercap = {{convert|500|impgal|abbr=on}} |primemover = [[Paxman (engines)|Paxman]] 12RPH, x 4 |cylindersize = {{convert|7|x|7+3/4|in|0|abbr=on}} |transmission = [[Vulcan Sinclair]] SCRD [[Fluid coupling|fluid]]; [[Fell (mechanics)|Fell]] central [[Transmission (mechanics)|gearbox]] |maxspeed = {{convert|84|mph|abbr=on}} |poweroutput = {{convert|2000|bhp|abbr=on|lk=on}} at 1,500 rpm |tractiveeffort = {{convert|25000|lbf|kN|0|abbr=on}} |trainheating = [[Steam generator (railroad)|Steam generator]] |locobrakeforce = {{convert|38|LTf|kN|abbr=on|lk=in}} |trainbrakes = [[Vacuum brake|Vacuum]] |operator = [[British Railways]] |powerclass = 6P5F, later Type 4 |fleetnumbers = 10100 |nicknames = ''Fell Diesel Locomotive'' |axleloadclass = |withdrawndate = 15 October 1958 |scrapdate = Derby Works, July 1960 }} '''British Railways 10100''' was an unusual experimental [[diesel locomotive]] known informally as ''The Fell Diesel Locomotive'' (after Lt. Col. L.F.R.