Built throughout the first half of the 20th Century and reaching the peak of their popularity in the 1930s and 40s, it was hoped turbine driven steam engines would provide a viable alternative to diesel-electric locomotives, which were just being introduced at that time.
Pros and Cons of Steam Turbine Locomotives
Pros
Steam turbine locomotives had numerous advantages over conventional steam locomotives.
- They were more efficient at high speeds
- They contained fewer moving parts and were more reliable.
- The absence of moving drive rods results in less wear on both the locomotive and the track.
Cons
Steam turbine locomotives also suffered from certain drawbacks as well.
- They were only efficient at high speeds.
- High efficiency could only be reached if the turbine operated in a vacuum. This was only possible with a steam condenser, which was a very bulky piece of equipment.
- Turbines can only rotate in one direction. A second turbine was necessary to allow the train to back up.
Forms of Steam Turbine Power
The power generated by the turbine could be utilized in one of two ways. The first was directly through a system of gears that connected the turbine to the wheels. The second was through an electric generator, which was turned by the turbine and provided power for the electric motors, which turned the wheels.( Lee, Thos.R.:"Turbines Westward",page 9,T.Lee Publications,1975)
Notable Steam Turbine Locomotives in the United States
At 123 feet long, the Pennsylvania Railroad built the largest turbine driven steam engine in the world. Built by the Baldwin Locomotive Works and officially designated as the S2 Turbine Locomotive, the engine was delivered to the Pennsylvanian Railroad in September, 1944.
Originally designed as 4-8-4 locomotive, meaning four trailing wheels, eight drive wheels and four guiding wheels, shortages caused by World War II meant that the locomotive was built with a 6-8-6 configuration instead. The S2 was the only American locomotive to be built with this configuration.
Numbered 6200, the steam turbine locomotive had a top speed of more than 160 kilometres per hour and was capable of generating 5.1 megawatts of electrical power. Unfortunately, while this locomotive was very efficient at high speeds and capable of pulling long trains almost effortlessly, it was very inefficient at low speeds, consuming huge quantities of steam and fuel. In the end, it was not able to compete with diesel locomotives and was scrapped in 1952.(Self, Douglas."The Pennsylvania Turbine Locomotive" The Self Site. Apr.9/09)
Notable Steam Turbine Locomotives in Britain
A somewhat more successful steam turbine locomotive was built in Britain, by the London, Midlands and Scottish Railway. Known as the Turbomotive, it boasted excellent thermal conversion, as compared to conventional steam engines.
Thanks to its six individually controllable steam nozzles, it also proved to be very fast. The LMS Turbomotive ran successfully until the late1940s, when it was involved in a head on collision with another train. The Turbomotive was converted into a conventional steam engine and put back into service. It was eventually withdrawn and discarded later in the early 50s.(Self, Douglas."The Turbomotive" The Self Site. Apr.9/09)
Turbine Electric Locomotives
In 1938, General Electric built two steam turbine electric locomotives for the Union Pacific Railroad. These locomotives were essentially power plants on wheels and were extremely complex. They were also the only condensed steam locomotives ever built in the United States. The boiler provided steam for a turbine that turned an electric generator, which provided power for the electric motors that turned the wheels.
However, these locomotives proved to highly unreliable, with breakdowns occurring often, usually as a result of coal dust or water shorting out the locomotives’ electrical components. As a result, the widespread use of head-end power would not occur until the early 1970s.(Self. Douglas. "The Union Pacific Turbine Locomotive." The Self Site. Apr.9/09)
Even though steam turbine locomotives showed initial promise, in the end, they could not compete with the economy and efficiency of diesel locomotives.
Union Pacific's Turbine Electric Locomotive
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