Saturday, 5 February 2011

A diesel-steam locomotive

I once had a fondness for railways. It was not so much the trains but the actual engineering; the bridges, tracks, and tunnels etc. However, osmosis did mean that I picked up some basic knowledge about the locomotives.

Over the years the various railway companies tried various experimental schemes for locomotives. Some of these are famous, such as Bullied's Leader class. However, there are undoubtedly many weird and wonderful experiments that I have never come across.

Whilst browsing the web somnolently, I came across a webpage on the LNER Encyclopedia. The page details the Kitson-Still locomotive built in the 1930s. It fascinates me as it shows the tentative way that many established organisations approach new technology.

At the time diesel engines and transmissions were relatively new and unreliable, especially in the sizes needed by a steam locomotive. The technology was a step too far for our mostly conservative railway companies. The Kitson-Still was designed to overcome some of these problems.

Diesel engines work by compressing diesel until it spontaneously ignites. Instead of having a seperate diesel engine, the Kitson-Still injected diesel into the opposite side of the cylinders from the steam, allowing the pressure of the steam to compress it to ignition. Hence this literal form of diesel injection would give the steam engine more power.

It was also more efficient - exhaust gasses from the diesel were taken through the boiler, preheating the water. In this manner, the locomotive got up to 40% efficiency - unheralded at the time.

Of course it was a technological dead-end. Diesel technology improved rapidly over the years, and the idea never got around many of the disadvantages of steam - whilst diesel and electric locomotives can be started at the flock of a switch, it takes many hours for a steam locomotive to get to working temperatures. But I must admit to a certain fondness towards this idea.

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