Steam turbine locomotive

Steam turbine locomotive image

Ljungström steam turbine locomotive with preheater (circa 1925) (Swedish National Museum of Science and Technology).

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.

Contents

Advantages

  • 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.

Disadvantages

  • High efficiency is ordinarily obtained only at high speed (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). 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.

Drive methods

There are two ways to drive the wheels: either directly via gears, or using generator-driven traction motors.

Direct drive

Argentina

The route from Tucumán to Santa Fe in Argentina goes through mountainous terrain with few opportunities to take on water. In 1925 the Swedish firm NOHAB built a turbi... ...read more

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