The Sacre Class D12 (GCR Class 6B) 4-4-0 Locomotives
During the mid-1870s, a number of British locomotive designers almost simultaneously adopted the concept of a bogie with a move from 2-4-0 designs to 4-4-0 designs. Previously there seems to have been a cultural suspicion of bogies in Britain, and many other countries were using bogie designs well before Britain. One of these designers was Sacre who introduced the 4-4-0 to the Manchester Sheffield & Lincoln Railway (MS&LR, later GCR) in 1877 with his Class 6B (LNER Class D12). In common with many of his contemporaries, Sacre did not take advantage of the resulting longer frame length with a longer boiler. Hence the D12s had long flat platforms in front of their smokeboxes - a characteristic of many 4-4-0s during this period. A total of twenty seven Class 6B locomotives were built in four batches between 1877 and 1880.
The D12s continued Sacre's preference for double frames. Although the double frames ran the full length of the locomotive, three ornamentally curved slots were cut into them, in order to save weight and increase accessibility. The front driving axle had bearings on both frames, but the rear axle only had bearings on the outside frame. Sacre's later cab design with side sheets was fitted.
The boiler was a round topped design operating at 140psi. Although this was the highest pressure used by Sacre to date, it was still lower than the standards of the day.
The D12s were built with the Smith simple vacuum brake system. This had a major design flaw, in that the brakes ceased to function if the train (and hence brake pipe) became severed. In 1881, the MS&LR directors decided to replace the flawed Smith system with the automatic vacuum brake system. However, no practical movement towards replacement had occurred by 1884 when D12 No. 434 was involved in a serious accident. Whilst working an express from Manchester London Road, No. 434 broke a crank axle at Bulhouse Bridge (approaching Penistone). The locomotive and tender managed to remain on the track, but the lurch broke the connection between the tender and leading vehicle. Without any brakes or locomotive restraining it, the train derailed and plunged down the embankment killing 24 passengers and injuring 60. The failings of the Smith system were identified in the resulting Board of Trade investigation, but the Directors continued to drag their feet. Three years later after a stern reminder from the Board of Trade, the Directors finally took action. No. 442 was fitted with the automatic vacuum brake system, and the remaining D12s were fitted over the next year or so.
Reboilering of the D12s started in the late 19th century by the MS&LR. The new boilers had more but smaller tubes. The grate was also slightly larger. After 1900, Robinson fitted longer smokeboxes and the standard Robinson chimney. The original iron buffer beams were replaced with steel buffer beams at about this time.
When built, the D12s hauled the MS&LR's best trains, and they appear to have performed these duties very successfully. Initial duties included the Liverpool to Hull trains, and the MS&LR legs of the Manchester to Kings Cross trains. Initial allocations were to Gorton, Retford, Sheffield, and Liverpool.
After Sacre's retirement in 1886, the D12s in common with many of his other designs, were quickly displaced to secondary duties. For much of the next 30 years, the D12s were restricted to Lincolnshire and the Cheshire Lines.
Between 1912 and 1914, the entire class was put on the GCR Duplicate List and a suffix 'B' added to all of their numbers. Motive power shortages during World War 1 appear to have postponed actual withdrawals until 1919. With a wartime maintenance backlog of their own, the Great North of Scotland Railway (GNSR) borrowed five D12s between 1920 and 1921. This seems an odd choice of locomotive because the GNSR used the Westinghouse brake system. No. 442B was recorded operating as a goods yard pilot in Aberdeen, but it is unclear exactly what work the other D12s actually performed.
In 1921, the D12s were allocated to Gorton (5), Trafford Park (2), Stockport (2), Annesley (2), New Holland (2), Immingham (2), Liverpool (1), Walton (1), Leicester (1). Twelve D12s entered LNER ownership at Grouping in 1923. LNER withdrawals were a slow and drawn-out affair, with the last D12 surviving until 1930. The last surviving D12 was No. 442B. Allocated to Annesley, No. 442B hauled the well-known 'Dido' staff train between Annesley depot and Bulwell Common station (near Nottingham). This low mileage duty ensured that No. 442B lasted three years longer than any other D12. It almost became the sole surviving Sacre locomotive, but J58 No. 6483 lasted a few months longer.
Technical Details
| Cylinders (x2): | (inside) | 17.5x26in. |
| Motion: | Stephenson | |
| Valves: | slide | |
| Boiler: | Max. Diameter: | 4ft 6in |
| Pressure: | 140psi | |
| Heating Surface: | Total: | 1113 sq.ft. |
| Firebox: | 96 sq.ft. | |
| Tubes: | 1017 sq.ft. (204x 1.75in) | |
| Grate Area: | 15.64 sq.ft. | |
| Wheels: | Leading: | 3ft 3.5in |
| Coupled: | 6ft 3.5in | |
| Tender: | 3ft 9.5in | |
| Tractive Effort: | (@ 85% boiler pressure) | 12,550 lb |
| Wheelbase: | Total: | 41ft 8.25in |
| Engine: | 20ft 9.5in | |
| Tender: | 12ft 0in | |
| Weight (full): | Total: | 69 tons 13cwt |
| Engine: | 43 tons 19cwt | |
| Tender: | 25 tons 14cwt | |
| Max. Axle Load: | 17 tons 12cwt |
Preservation
The last D12 was withdrawn in 1930, and none survived into preservation.
Models
I am not aware of any models of the D12s in any scale.
Acknowledgements
Thank you to Malcolm Peirson for the photograph of GCR No. 440.