The class was introduced by Nigel Gresley in July 1926, based on his previousClass J38 (introduced in January 1926) but with largerdriving wheels. The larger wheels enabled them to be used on both passenger and freight trains, although at the expense of a lowertractive effort. As a result they were given the BRpower classification 4P/5F, rather than the 6F of the earlier class. A total of 289 examples were built over the next fifteen years, mostly built by the LNER'sDarlington Works although 28 were built byBeyer, Peacock and Co. in 1935.
The larger wheels necessitated the provision of lowsplashers over the front two wheels, which is the main means of differentiating between the two classes. However the increased speed afforded by the larger wheels caused the big end bearings to overheat, something that was aggravated by their use on passenger trains, and reliability suffered as a result. The locomotives were all fitted withsuperheaters and Ross'Pop' safety valves.[4][3]
J39/2 No. 64898 at Lincoln, Pelham St. Level-Crossing 21 May 1956
All passed intoBritish Railways ownership in 1948 and they were numbered 64700-64988. They began to be withdrawn from service in 1959 and all examples had been scrapped by the end of 1962.[5] No. 64747 served out the remainder of its days as a stationary boiler at the Woodford shed until October 1964.[6]
On 31 July 1927, locomotive No. 1459 was derailed at 9.33pm, 200 yards east of the Sandsend tunnel mouth on the Whitby-Loftus line whist hauling the No. 70 West Hartlepool to Whitby return excursion.[7]
Circa 1930, locomotive No. 1448 was derailed by trap points at Lumpsey Colliery,Brotton,Yorkshire.[8]
On 28 August 1950, the connecting rod of a locomotive of this class became detached and consequently pierced the firebox, scalding the driver.[9]
On 23 October 1950, locomotive No. 64880 was hauling a passenger train that was derailed atDrumburgh,Cumberland due to the condition of the track. Two people were killed and three were injured.[10]
Boddy, M.G.; Neve, E.; Tee, D.F.;Yeadon, W.B. (September 1982). Fry, E.V. (ed.).Locomotives of the L.N.E.R., part 6A: Tender Engines - Classes J38 to K5. Kenilworth:RCTS.ISBN0-901115-53-3.
Casserley, H.C. (1960).The Observers book of railway locomotives of Britain. Federick Warne & Co. Ltd.
Earnshaw, Alan (1993).Trains in Trouble: Vol. 8. Penryn: Atlantic Books.ISBN0-906899-52-4.
Hughes, Geoff (August 1992). "Talking to Thompson part II".Steam World. No. 62. Peterborough: EMAP Apex Publications.
Ian Allan ABC of British Railways Locomotives (1962 ed.).
Stubbs, W.T.; Boddy, M.G. (1963).Locomotive stock book 1963. Railway Correspondence and Travel Society.
Trevena, Arthur (1981).Trains in Trouble: Vol. 2. Redruth: Atlantic Books.ISBN0-906899-03-6.
