| GCR Class 9P LNER Class B3 | |
| Powertype: | Steam |
| Designer: | John G. Robinson |
| Builder: | GCR, at Gorton Works |
| Builddate: | 1917, 1920 |
| Totalproduction: | 6 |
| Whytetype: | 4-6-0 |
| Uicclass: | 2'C |
| Leadingdiameter: | 3feet |
| Driverdiameter: | 6feet |
| Wheelbase: | 52feet |
| Length: | 63feet |
| Fueltype: | Coal |
| Diameterinside: | 5feet to 5feet outside |
| Boilerpressure: | 180lbf/in2 |
| Fireboxarea: | 163square feet |
| Totalsurface: | 2044square feet |
| Superheaterarea: | 343square feet |
| Cylindercount: | Four |
| Cylindersize: | 16× |
| Valvegear: | Stephenson |
| Valvetype: | 8inches piston valves |
| Tractiveeffort: | 251452NaN2 |
| Numinclass: | 6 |
| Nicknames: | Lord Faringdon |
| Withdrawndate: | 1946–49 |
| Disposition: | All scrapped |
GCR Class 9P was a design of four-cylinder steam locomotive of the 4-6-0 wheel arrangement built for hauling express passenger trains on the Great Central Railway in England. A total of six were built: one in 1917, and five in 1920. They were sometimes known as the Lord Faringdon class, from the name of the first one built.
John G. Robinson served as Chief Mechanical Engineer of the Great Central Railway (GCR) from 1900 to 1922. Towards the end of his period of office, he introduced two classes of 4-6-0 locomotive with four cylinders and large-diameter boilers. They differed primarily in the diameter of their driving wheels: the first design, Class 9P (LNER Class B3 from September 1923), had 6feet diameter wheels, for express passenger service; and the second, Class 9Q (LNER Class B7), had 5feet wheels, for mixed-traffic work.
The first locomotive of Class 9P to be built was costed at £5,871. The four cylinders had a bore of 16inches and a stroke of 26inches. They were set in line (like the LNWR Claughton Class), with the inside cylinders driving the front coupled axle, and the outside cylinders driving the middle coupled axle (like the GWR Star Class). The 8inches piston valves were actuated by two sets of Stephenson valve gear, mounted inside the frames and operating the valves of the outside cylinders through rocking shafts placed behind the cylinders. These rocking shafts caused the two valves on each side to move forwards and backwards together, and since the inside and outside cylinders on each side were out of phase by 180°, the valves of the outside cylinders were arranged for outside admission, instead of the normal inside admission layout. The boiler was the Gorton "No. 7 Standard", which was already used on two other GCR 4-6-0 classes: Class 1 (LNER Class B2) and Class 1A (LNER Class B8); it would later be used on Class 9Q as well. In July 1928, this boiler was assigned to LNER Diagram 13.
The complicated cylinder castings, which involved tortuous narrow steam passages to provide inside admission for the inside cylinders and outside admission for the outside cylinders, resulted in poor steam flow; this, together with leakages around the piston valves, led to a high coal consumption which became particularly apparent once the locomotives were being used on trains out of King's Cross. Nigel Gresley, the Chief Mechanical Engineer of the LNER, decided to fit poppet valves, but instead of operating these by Lentz valve gear, as he had done with some of his other poppet valve fitments (such as Class B12), Gresley chose to use Caprotti valve gear. This was driven from the driving axle by a longitudinal shaft along the centre of the locomotive to a transverse shaft above the cylinders. No. 6168 Lord Stuart of Wortley was modified in September 1929, followed by no. 6166 in December. In December 1929, class B3 was subdivided into two parts, and the locomotives modified with Caprotti valve gear were given the classification B3/2, and the unmodified locomotives became B3/1. On test, they showed a 16% reduction in coal consumption, and as a result, a further two more were modified to B3/2 – no. 6167 in June 1938, and no. 6164 Earl Beatty in June 1939. These used steam to close the valves, instead of the springs fitted to nos. 6166/8. It was intended to convert the remaining two Class B3/1 locomotives, but the outbreak of war meant that they were never modified, and retained Stephenson valve gear until withdrawal.
In 1943, no. 6166 Earl Haig of Class B3/2 was found to have cracked cylinders, and was selected by Edward Thompson for rebuilding with two outside cylinders, ten-inch piston valves actuated by Walschaerts valve gear and a round-top boiler of the same design (known as Diagram 100A) as was used on his Class B1 4-6-0. The wheels, bogie and rear part of the main frames were retained, as was the tender, but all the other components were new. It was reclassified B3/3, and returned to service in October 1943, retaining its number but losing its name, since there was no suitable place to affix the nameplates. No further rebuilds followed; the reconstruction weakened the frames, and although this locomotive was the sole member of the class to be inherited by British Railways, it survived only until 1949.
| Number | Built | Name | Rebuilt | Final LNER number | Withdrawn | |
|---|---|---|---|---|---|---|
| 1169 | November 1917 | Lord Faringdon | 1494 | December 1947 | ||
| 1164 | June 1920 | Earl Beatty | June 1939 (B3/2) | 1495 | September 1947 | |
| 1165 | July 1920 | Valour | 1496 | December 1947 | ||
| 1166 | August 1920 | Earl Haig | December 1929 (B3/2); October 1943 (B3/3) | 1497 | April 1949 | |
| 1167 | September 1920 | Lloyd George | June 1938 (B3/2) | 1498 | December 1947 | |
| 1168 | October 1920 | Lord Stuart of Wortley | September 1929 (B3/2) | 1499 (not carried) | September 1946 |
After the Grouping, the LNER increased the GCR numbers by 5000, this occurring in 1924–25. Under the 1946 renumbering, they were allotted 1480–5 in order of construction, but these were not applied, being amended later that year to 1494–9. No. 6168 was withdrawn before the number 1499 could be applied, but the others were renumbered in September and October 1946. No. 1497, the sole Class B3/3 rebuild, was the only one to survive nationalisation; it was duly allotted no. 61497, which was applied in April 1948.