GCR Class 9A
|GCR Classes 9A and 9A Alt.
LNER Class N4
N4/2 No. 69239 at Barnsley Locomotive Depot 10 April 1949
|Type and origin|
|UIC classification||C1 n2t|
|Gauge||4 ft 8 1⁄2 in (1,435 mm)|
|Driver diameter||5 ft 1 in (1.549 m)|
|3 ft 6 in (1.067 m)|
|Wheelbase||22 ft 6 in (6.86 m)|
|Axle load||16.75 long tons (17.02 t)|
|Weight on drivers||48.15–48.40 long tons (48.92–49.18 t)|
|Locomotive weight||61.50–61.95 long tons (62.49–62.94 t)|
|Boiler||LNER diagram 21|
|Boiler pressure||160 lbf/in2 (1.10 MPa)|
|Firegrate area||18.3 sq ft (1.70 m2)|
|964 sq ft (89.6 m2)|
|– Firebox||99 sq ft (9.2 m2)|
|– Total||1,063 sq ft (98.8 m2)|
|Cylinder size||18 in × 26 in (457 mm × 660 mm)|
|Valve type||Slide valves|
|Tractive effort||18,780 lbf (83.54 kN)|
|Axle load class||LNER/BR: Route availability 4|
Design and construction
Designed by Thomas Parker for the Manchester, Sheffield and Lincolnshire Railway (MS&LR), a total of 55 locomotives were constructed up to 1892. The MS&LR changed its name to the GCR in 1897. In 1892 the final fourteen locomotives were built with a larger coal bunker, increasing their weight to 61.95 long tons (62.94 t). This last batch was classified as Class 9A Altered, sometimes abbreviated as 9A Alt.
The GCR 9A locos were reclassified as N4 under the LNER locomotive numbering and classification system when the GCR was absorbed into the London and North Eastern Railway after the 1923 grouping. The original design were N4/1 and those with extended bunkers N4/2.
In 1925, shorter chimneys began to be fitted to bring the N4s within the LNER composite loading gauge, creating two further variants N4/2 (short bunker) – the existing N4/2s being recoded as N4/3s – and N4/4 (long bunker).
They were built in three batches and numbered 161, 165, 173 (later renumbered 512–514), 601–638, and 712–725. GCR locos had 5000 added to their original numbers when the line was absorbed by the LNER in 1923, resulting in numbers ranging between 5512 and 5725. As part of the LNER's numbering rationalisation scheme introduced in 1946, the surviving 24 N4s were renumbered between 9225 and 9247 with the earliest built receiving the lowest number, and so on. British Railways, formed on 1 January 1948, added 60000 to all LNER loco numbers.
- Boddy, M. G.; Brown, W. A.; Fry, E. V.; Hennigan, W.; Hoole, Ken; Manners, F.; Neve, E.; Platt, E. N. T.; Proud, P.; Yeadon, W. B. (March 1977). Fry, E. V., ed. Locomotives of the L.N.E.R., Part 9A: Tank Engines—Classes L1 to N19. Kenilworth: RCTS. ISBN 0-901115-40-1.
- Casserley, H.C. & Johnston, Stuart W. (1974) . Locomotives at the Grouping 2: London & North Eastern Railway. Shepperton, Surrey: Ian Allan Limited. ISBN 0-7110-0553-2.
- Allan, Ian (1947). ABC of LNER Locomotives 1947. Ian Allan Ltd.
|Wikimedia Commons has media related to GCR Class 9A / LNER Class N4.|