LNWR Experiment Class
No. 165 City of Lichfield at Hillhouse steam shed
Type and origin Power type Steam Designer George Whale Builder Crewe Works Serial number 4505–09, 4550–59, 4620–39, 4680–89, 4770–89, 4830–69 Build date 1905–1910 Total produced 105 Rebuild date 1915 Number rebuilt 1
Specifications Configuration: ​  • Whyte 4-6-0  • UIC 2′C n2 (rebuilt: 2′C n4) Gauge 4 ft 8+1⁄2 in (1,435 mm) Leading dia. 3 ft 9 in (1.143 m) Driver dia. 6 ft 3 in (1.905 m) Loco weight 65.75 long tons (66.81 t) Fuel type Coal Boiler pressure 175 psi (1.21 MPa) Heating surface 2,041 sq ft (189.6 m2) Cylinders Two (rebuilt: four) Cylinder size 19 in × 26 in (483 mm × 660 mm); rebuilt: 14 in × 26 in (356 mm × 660 mm) Valve gear Joy; rebuilt: Dendy-Marshall Valve type Slide valves
Performance figures Tractive effort 18,616 lbf (82.8 kN); rebuilt: 20,232 lbf (90.0 kN)
Career Operators London and North Western Railway → London, Midland and Scottish Railway Power class LMS: 3P Number in class 1 January 1923: 105 Withdrawn 1925–1935 Disposition All scrapped

The London and North Western Railway (LNWR) Experiment Class was a class of 4-6-0 steam locomotive designed by George Whale.

Career

They were an extended version of the Whale's Precursor Class 4-4-0, with slightly smaller driving wheels. The first of the class, 66 Experiment was built in 1905 and a total of 105 were constructed up until 1910. The LNWR reused numbers and names of withdrawn locomotives, with the result that the numbering system was completely haphazard. A 19in Express Goods Class with smaller driving wheels was also built from 1906. From 1911, a superheated version, the Prince of Wales Class was built.

In 1915, 1361 Prospero was experimentally rebuilt with four cylinders, Dendy Marshall valve gear and superheated. The conversion was not repeated. Only two other engines were given superheaters; 2624 Saracen and 1993 (LMS 5472) Richard Moon.

All entered London, Midland and Scottish Railway (LMS) stock upon grouping in 1923. The LMS gave them the power classification 3P. The LMS renumbered them into a more logical series of 5450–5553 according to date of construction. An exception was made for 1361 Prospero which became 5554. Not all however survived long enough to receive their LMS numbers — withdrawals had started in 1925. In 1934 the thirteen then remaining were renumbered with the addition of 20000 to their numbers make room for Black Five, Patriot and Jubilee class locomotives. The final engine was withdrawn the following year and none were preserved.

Fleet list

Accidents and incidents

• On 15 October 1907, a mail train hauled by No. 2052 Stephenson was derailed at Shrewsbury, Shropshire due to excessive speed on a curve. Eighteen people were killed.
• On 5 July 1923, an express passenger train hauled by 1406 George Findlay was involved in a rear-end collision with a freight train at Diggle, Lancashire due to confusion by the driver of the freight train over flag signals. Four people were killed.^[2]