Steam & Excursion > Whazzit? (15)

Here's another one.

-LD

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Where's professor Schmidt, when you need him?

​W.

Puts me in mind of a cylinder of a Manitou & Pikes Peak engine.

Cylinders on a Vauclain compound.

Yes, these are the cylinders of a Vauclain compound locomotive, and the Manitou & Pikes Peak engines were so equipped.  A compound locomotive is one in which the steam is passed tthrough not just one, but two cylinders in succession, the first exhausting into the second, then exhaused up the stack, in order to extract more energy. 

Baldwin was the only builder of Vauclains.  On high drivered engines the smaller (high pressure) cylinder was mounted on top, but on low drivered engine such as seen here the larger (low pressure) cylinder was on top for better ground clearance.  The piston rods of both cylinders were attached to a common crosshead and main rod, as seen below on this outside frame engine, so moved in unison.  All Vauclains were piston valve equipped, with the valve chambers between the frames, shown in the second picture below.  The rest of the running gear was unchanged from conventional engines.

As on all compounds there was a starting valve, operated by the engineer, to switch the larger (normally low pressure) cylinders to use high pressure steam until after a few turns of the drivers until there was sufficient exhaust pressure built up to switch to run compound.  Later, on other compounds an automatic changeover valve was developed.

Vauclain compounds were built from about 1895 to 1910, and were widely used.  When, as Wes pointed out in his post above, "Professor Schmidt" perfected the superheater, the Vauclain as well as most other compound engine designs pretty much disappeared - most converted to superheated conventional two cylinder simple engines.  EXCEPT for Mallet articulated compounds which continued to be built new to the very end in the mid 1950's!

-LD

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I know Canadian Pacific had some Vauclain-type compounds, and built much of their own power. Were their Vauclain compounds from Baldwin, or did they build their own? I'm 400 miles from my reference material so can't check. CP was also an early adopter and leader in superheating (the Vaughan-Horsey type) though their later power used standard type E for the most part (iirc)

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Darren Boes
Lethbridge, AB
Southern Alberta Railfan