The Robinson Class B6 (GCR Class 8N) 4-6-0s
The first Great Central (GCR) Class 8N (LNER B6), No. 416, was built in 1918 at the same time as a batch of O5 2-8-0 and shared the same boiler, cylinders, and motion. Two more B6s were ordered in 1921 at the same time as three B7 locomotives, which were a mixed traffic version of the B3 Lord Faringdon class. It appears that Robinson was considering a series of trials between these two types, but the B7 order was expanded before it was completed. No further B6s were built.
The B6 was based on the B8 (GCR Class 1A). The B8 had large inside cylinders resulting in relatively small axleboxes on the driving axles. The B6 solved this by having outside cylinders. The B7s had four cylinders, resulting in a balanced design with smaller cylinders. The B6 boiler was also improved over that of the B8, and gained a good reputation for free steaming.
During their life, the B6s and O5s often interchanged boilers. As the O5 Diagram 15B boilers wore out, they were replaced with Diagram 15 boilers converting them to Class O4. The B6s were never rebuilt with Diagram 15 boilers, and two Diagram 15B boilers had to be specially built in 1941.
The B6s were built with Robinson's header discharge valve, but were eventually fitted with Gresley's anti-vacuum valve. The LNER replaced the original chimneys with a Doncaster design, but the B6s were never cut down to the LNER composite loading gauge.
The prototype, No. 416, was initially allocated to Gorton, but quickly moved to Neasden in 1919. The later two were allocated to Woodford in 1921, where No. 416 was allocated at the end of the year. At Grouping (1923), they were allocated to Gorton again, and operated the overnight goods trains to and from Hull. During the mid-1920s, they were moved to Sheffield, followed by the West Riding in February 1928. Allocations within the West Riding varied, and the B6s often ran specials to destinations such as Liverpool, Banbury, and Manchester.
In 1934, the B6s moved back to Sheffield in June 1934 and operated a huge variety of different passenger and goods trains. In 1946 the B6s moved to Ardsley to operate goods trains, before being withdrawn at the end of 1947.
Technical Details
| Cylinders: | (2x outside) | 21x26in. |
| Motion: | Gear: | Stephenson |
| Valves: | 10in Piston | |
| Boiler: | Max. Diameter: | 5ft 6in |
| Pressure: | 180psi | |
| Diagram No.: | 15B | |
| Heating Surface: | Total: | 2123 sq.ft. |
| Firebox: | 174 sq.ft. | |
| Tubes: | 1050 sq.ft. (116x 2.25in dia) | |
| Superheater: | 308 sq.ft. (28x 1.06in dia) | |
| Flues: | 591 sq.ft. (28x 5.25in dia) | |
| Grate Area: | 26.24 sq.ft. | |
| Wheels: | Leading: | 3ft 6in |
| Coupled: | 5ft 8in | |
| Tender: | 4ft 4in | |
| Tractive Effort: | (@ 85%) | 25,798lb |
| Wheelbase: | Total: | 50ft 8.5in |
| Engine: | 27ft 6in | |
| Tender: | 13ft 0in | |
| Weight (full): | Total: | 121 tons 4cwt |
| Engine: | 72 tons 18cwt | |
| Tender: | 48 tons 6cwt | |
| Max. Axle Load: | 18 tons 4cwt |
Preservation
The last B6 was scrapped in 1947, and none of the B6s survived into preservation.
Models
I am not aware of any models of the B6s in any scale.