| Group Numbers |
R700 to R769 |
| Wheel arrangement |
4-6-4 “Hudson” |
| Nominal coupled wheel diameter |
6 feet 015/16 inches (1853 mm) |
| Overall length engine and tender |
77 feet 3¼ inches (23.55 m) |
| Wheelbase Rigid Engine and tender |
12 feet 10 inches (3.91 m) 67 feet (20.42 m) |
| Weight in working order Engine Tender Total |
107 tons 12 cwt (109.3 tonne) 79 tons 16 cwt (81.1 tonne) 187 tons 8 cwt (190.4 tonne) |
| Adhesive weight |
58 tons 10 cwt (59.4 tonne) |
| Maximum axle load |
19 tons 10 cwt (19.8 tonne) |
| Boiler heating surface area Flues and tubes Firebox Superheater Total |
1,958 sq. feet (181.9 m2) 285 sq. feet (26.5 m2) 462 sq. feet (42.9 m2) 2,705 sq. feet (251.3 m2) |
| Grate area |
42 sq. feet (3.9 m2) |
| Working boiler pressure |
210 psi (1,450 kPa) |
| Cylinder (2) diameter and stroke |
21½ inches x 28 inches (546 mm x 711 mm) |
| Tractive effort at 85% boiler pressure |
32,080 lbf ( 143 kN) |
| Maximum permissible speed |
70 mph (112 km/h) |
| Tender capacity Water Coal |
9,000 gallons (40,900 l) 6 tons (6.1 tonne) |
| Mechanical stoker |
Standard Stoker MB-1 |
| Built by |
North British Locomotive Company, Glasgow, Scotland, in 1951 -1952 |
