Princess Royal Class

Princess Royal Class
One of the two preserved Princess Royals, 6201 Princess Elizabeth at Castleton South Junction.
Type and origin Power type Steam Designer William Stanier Builder LMS Crewe Works Build date 1933 (2), 1935 (10) Total produced 12 Rebuild date 1952 (from Turbomotive) Number rebuilt 1
Specifications Configuration: ​  • Whyte 4-6-2  • UIC 2′C1′ h4 Gauge 4 ft 8 1⁄2 in (1,435 mm) Leading dia. 3 ft 0 in (1 m) Driver dia. 6 ft 6 in (2 m) Trailing dia. 3 ft 9 in (1 m) Minimum curve 6 chains (121 m) normal 4 1⁄2 chains (91 m) dead slow Wheelbase 63 ft 10 in (19.456 m)  • Engine 37 ft 9 in (11.506 m)  • Drivers 15 ft 3 in (4.648 m)  • Tender 15 ft 0 in (4.572 m) Length 74 ft 4 1⁄4 in (22.663 m) Width 9 ft 0 in (2.743 m) Height 13 ft 3 in (4.039 m) Axle load 22.50 long tons (22.86 t)  • Leading 21.00 long tons (21.34 t)  • Coupled 22.50 long tons (22.86 t)  • Trailing 16.00 long tons (16.26 t)  • Tender axle Front: 18.60 long tons (18.90 t) Middle: 17.80 long tons (18.09 t) Rear: 18.25 long tons (18.54 t) Adhesive weight 67.50 long tons (68.58 t) Loco weight 104.50 long tons (117.04 short tons; 106.18 t) 46202: 110.55 long tons (123.82 short tons; 112.32 t) Tender weight 54.65 long tons (61.21 short tons; 55.53 t) Fuel type Coal Fuel capacity 9.00 long tons (10.08 short tons; 9.14 t) later 10.00 long tons (11.20 short tons; 10.16 t) Water cap 4,000 imp gal (18,000 l; 4,800 US gal) Firebox type    • Firegrate area 45 sq ft (4.2 m2) Boiler: ​  • Model LMS type 1  • Tube plates 19 ft 3 in (5.867 m)  • Small tubes 2 3⁄8 in (60 mm), 32 off  • Large tubes 5 1⁄8 in (130 mm), 123 off Boiler pressure 250 psi (1.7 MPa) Heating surface    • Tubes and flues 2,299 sq ft (213.6 m2)  • Firebox 190 or 217 sq ft (17.7 or 20.2 m2) Superheater: ​  • Heating area 584 sq ft (54.3 m2) Cylinders 4 Cylinder size Production Models: 16 1⁄4 in × 28 in (413 mm × 711 mm) Turbomotive rebuild: 16 1⁄2 in × 28 in (419 mm × 711 mm) Valve gear Walschaerts 6205 had outside Walschaerts with rocking shafts operating inside valves. Valve type Piston valves
Performance figures Tractive effort 40,286 lbf (179.20 kN) (production engines) 41,535 lbf (184.76 kN) (turbomotive rebuild)
Career Operators London, Midland and Scottish Railway London Midland Region of British Railways Power class 7P reclassified 8P in 1951 Numbers 6200–6201, 6203–6212, 46200–46212 Withdrawn 1952 (1), 1961 (6), 1962 (6) Preserved 6201, 6203 Disposition Two preserved, remainder scrapped

The London, Midland and Scottish Railway (LMS) Princess Royal Class is a class of express passenger steam locomotive designed by William Stanier. They were Pacifics (i.e. had a 4-6-2 wheel arrangement). Thirteen examples were built at Crewe Works, between 1933 and 1935, and two are preserved.

When originally built, they were used to haul the famous Royal Scot train between London Euston and Glasgow Central.

A prototype batch of three locomotives was to be constructed in 1933. Two were constructed as drawn but the third set of frames was retained as the basis for an experimental turbine locomotive.

The third prototype was constructed with the aid of the Swedish Ljungstrom turbine company and known as the Turbomotive, although not named. It was numbered 6202, in sequence with the Princess Royals. Although 'generally similar' to the rest of the Princess Royals, and 'not all that much different', it used a larger 40 element superheater to give a higher steam temperature, more suitable for turbine use. This boiler was also domeless as would later be used for the second batch of the Princess Royals. The continuous exhaust of the turbine, rather than the sharper intermittent blast of the piston engine, also required changes to the draughting and the use of a double chimney. It entered service in June 1935 on the London–Liverpool service.

This Turbomotive was rebuilt in 1952 with conventional 'Coronation' cylinders and named Princess Anne, but was soon destroyed in the Harrow and Wealdstone rail crash.