Steam Trains and Engines

Shortly before the outbreak of war, the Northern Region of the French National Railways (S.N.C.F.) placed in service seven 4-6-4 express locomotives designed by Monsieur de Caso and designated Classes ' R ' and ' S.' The eighth engine was to have been a Lungstrom turbine, but due to the war this was never carried out and the locomotive entered service after the war as a modified Class ' S ' 4-cylinder compound numbered 232.U1.

Ul may be regarded as the last word in French steam locomotive design, and probably the most advanced steam engine in the world today. Basically it is a de Glehn compound with the difference that the high-pressure cylinders are between the frames; for ease of maintenance the Dabeg poppet valves of the other 4-cylinder compounds have been omitted and Walschaerts valve gear, with a conjugate^ drive to the inside cylinders, is employed.

Also, unlike most compound engines in France, the respective cut-offs arc not independently variable; they remain at a fixed ratio. However, through a system of servomotors anil air-operated regulators, the locomotive starts as a 4-cylinder simple and automatically changes over to compound working as speed is gained. Other refinements include a Standard 3-jet stoker, feed water heater, roller bearings on all axles, brakes on bogie and trailing wheels, and self-adjusting axleboxes; the latter, combined with equalised springing, assures magnificently smooth riding, as I have discovered myself during recent journeys on this fine locomotive.

232.Ul has spent her entire life based at La Chapelle depot in Paris, working high-speed expresses north to Aulnoye and Lille; now that these services have been taken over by electric traction, Ul is scheduled for museum preservation.