The LMS Turbomotive was a modified Princess Royal Class steam locomotive designed by William Stanier, (inspired by the 1920’s built Ljungström locomotive from Sweden), and built by the London, Midland and Scottish Railway in 1935 at the LMS Crewe Works. It used turbines instead of conventional steam cylinders. It was later rebuilt as a conventional locomotive 46202 Princess Anne.
The forward turbine had 18 rows of blading. Output was 2,400 hp (1,800 kW) at 7060 rpm, corresponding to running at 62 mph (100 km/h). Boiler pressure was 250 psi (1.7 MPa). The turbine was designed to operate into a maximum back-pressure of 2 psi (14 kPa), allowing a conventional double blast-pipe to provide the boiler draught, and eliminating draught fans, which always seemed to give a disproportionate amount of trouble.
The reverse turbine had 4 rows of blades. It was engaged by a dog clutch, activated when the reverser lever was set to "0". This was originally steam-operated by a small piston and cylinder.
Compared to some other experimental steam locomotives of the era such as the LNER Class W1, Turbomotive was relatively successful, showing a saving of coal compared to a normal reciprocating engine and no hammer blow on the track. Because steam turbines are highly inefficient when throttled (not a problem on steamships, where turbines typically run at constant output, but a major disadvantage for a railway locomotive which has to run at different speeds), power was instead controlled by turning on a different number of nozzles (from the six available) through which steam was admitted to the turbine. One disadvantage of the design was that the small reverse turbine only had sufficient power for manoeuvring "light engine" and the locomotive always had to be turned to face forwards in order to pull a train. It is unclear whether the LMS Turbomotive did pull passenger trains during World War 2 or not.
When a turbine failure occurred in 1949 it was considered uneconomic to repair during post-war austerity measures, so the locomotive was taken out of service pending a rebuild.
BR 46202 Princess Anne[]
46202 was rebuilt as a conventional locomotive in 1952, using new mainframes and a set of cylinders of the same type as used in the "Coronation" Class, and named Princess Anne. On October 8, 1952, The London Midland and Scottish Railway (LMS) Jubilee Class No. 45637 which was double heading with LMS No. 46202 "Princess Anne" (Formerly LMS No. 6202, Formerly the "LMS Turbomotive") was destroyed in the Harrow & Wealdstone Rail Crash. In the end of that crash, LMS No. 46202 was so badly damaged from the wreck that it was deemed "Damaged-Beyond Repair" and it was ultimately scrapped. The destruction of No. 46202 led to the construction of BR Standard Class 8 number 71000, Duke of Gloucester.
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