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Concept
Steam turbine locomotive
Résumé
A steam turbine locomotive is a steam locomotive which transmits steam power to the wheels via a steam turbine. Numerous attempts at this type of locomotive were made, mostly without success. In the 1930s this type of locomotive was seen as a way both to revitalize steam power and challenge the diesel locomotives then being introduced.
High efficiency at high speed.
Far fewer moving parts, hence potentially greater reliability.
Conventional piston steam locomotives give a varying, sinusoidal torque, making wheelslip much more likely when starting.
The side rods and valve gear of conventional steam locomotives create horizontal forces that cannot be fully balanced without substantially increasing the vertical forces on the track, known as hammer blow.
High efficiency is ordinarily obtained only at high speed and high power output (though some Swedish and UK locomotives were designed and built to operate with an efficiency equal to or better than that of piston engines under customary operating conditions including part-load). Gas turbine locomotives had similar problems, together with a range of other difficulties.
Peak efficiency can be reached only if the turbine exhausts into a near vacuum, generated by a surface condenser. These devices are heavy and cumbersome.
Turbines can rotate in only one direction. A reverse turbine must also be fitted for a direct-drive steam turbine locomotive to be able to move backwards.
There are two ways to drive the wheels: either directly via gears, or using generator-driven traction motors.
The route from Tucumán to Santa Fe, Argentina goes through mountainous terrain with few opportunities to take on water. In 1925 the Swedish firm NOHAB built a turbine locomotive similar to Fredrik Ljungström's first design. The condenser worked quite well - only 3 or 4% of the water was lost en route and due only to leakage from the tank. The locomotive had reliability problems and was later replaced by a condenser-equipped piston steam locomotive.
Two attempts were made in France.
Source officielle
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